bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of
Lactobacillus bulgaricus
Bacteriophage ch2
Authors: Chow Joseph J. , Batt Carl A. , Sinskey Anthony J.
Published: January 2020

Bacteriophage ch2, a virulent bacteriophage of
Lactobacillus bulgaricus
CH2, was characterized according to its morphology, genome size, structural proteins, and growth kinetics. Electron micrographs revealed that bacteriophage ch2 has an icosahedral head of 50-nm diameter and a long tail of 170 nm. Its genome is linear and 35 kilobases in length, and its structural proteins consist of two major and eight minor proteins. One-step growth kinetics of bacteriophage ch2 under optimal conditions (45°C in MRS medium [Oxoid Ltd.]) showed that the latent time was 40 min, the rise period was 15 min, and the burst size was 130 bacteriophages per cell. To monitor the effects of bacteriophage infection on host growth and β-galactosidase production, the absorbance of the culture and the β-galactosidase activity were followed during the infection cycle. Before lysis the infected culture continued to grow and produce β-galactosidase at the same rate as the uninfected culture.
Populations of Methanogenic Bacteria in a Georgia Salt Marsh
Authors: Franklin Michael J. , Wiebe William J. , Whitman William B.
Published: January 2020

Methanogens represented about 0.5% of the total bacteria in sediments from a Georgia salt marsh in which
Spartina alterniflora
is the predominant vegetation. The population of methanogens was composed of at least two groups of nearly equal size. One group was represented by cocci which were able to utilize trimethylamine and were unable to use H
2
or acetate. The second group was composed of two subgroups which were able to utilize H
2
but were unable to use trimethylamine or acetate. The more common subgroup included rod- or plate-shaped methanogens which could utilize isopropanol in addition to H
2
and formate. The second subgroup included
Methanococcus maripaludis,
which utilized only H
2
and formate. Other groups of methanogens were also present, including
Methanosarcina
sp. which utilized acetate, H
2
, and methylamines. In addition to the overall variability in the types of methanogens, the numbers of methanogens in sediments also exhibited significant spatial variability both within and between tall- and short-
Spartina
zones.
Microbial Ecology of the Gut in Laboratory Stocks of the Migratory Grasshopper,
Melanoplus sanguinipes
(Fab.) (Orthoptera: Acrididae)
Authors: Mead Lorna J. , Khachatourians G. G. , Jones G. A.
Published: January 2020

Mean pH values in pooled samples of foregut, midgut, and hindgut from adult
Melanoplus sanguinipes
, which had been raised in the laboratory on barley shoots and wheat bran, were 5.15, 6.39, and 5.98, respectively. Homogenates of midgut/hindgut sections and frass (feces) yielded colony counts of bacteria by the spread plate method of 5.7 to 5.9 and 5.3 to 5.5 log
10
colonies per mg, respectively; there were no significant differences (
P
> 0.05) between counts obtained on several media or on media incubated aerobically or anaerobically. There was no evidence of significant populations of protozoa, fungi, or obligately anaerobic bacteria associated with the gut. A total of 168 pure strains of bacteria isolated from the gut sections were characterized and assigned to 11 taxonomic groups, including
Enterococcus
spp.,
Serratia liquefaciens, Pseudomonas
spp., and
Enterobacter
spp. Numbers of
Enterococcus
spp. in the gut were 2 to 3 orders of magnitude higher than those of the other genera. Strains representing only four of the groups were recovered from bran fed to the grasshoppers; the barley shoots, which were raised in sterile soil, appeared virtually sterile. Examination of the gut wall by scanning electron microscopy revealed the presence of epimural bacteria in the foregut and hindgut but not in the midgut. The distribution of epimural cocci and bacilli differed with the gut section examined. Numerous spherical to ovoid structures up to 10 μm in diameter, which were not identified, were associated with the microvillous surface of the midgut epithelium. Acetate was present in gut, hemolymph, and frass, and it was shown that representative isolates of
Enterococcus
spp. and
Enterobacter agglomerans
produced acetate when incubated in an aqueous suspension of bran. The egestion time of solid digesta, as measured with methylene blue-stained barley shoots, was 3.0 to 5.7 h. The results show that
M. sanguinipes
supported extensive indigenous populations of luminal and epimural bacteria in the gut which were composed predominantly of facultatively anaerobic species; the relatively short egestion time, indicating rapid passage of digesta through the gut, was consistent with the microscopic appearance of digesta residues in frass and could account, at least in part, for the absence of a significant population of obligately anaerobic bacteria from the gut.
Enzymatic dehalogenation of chlorinated nitroaromatic compounds
Authors: Thiele J , Müller R , Lingens F
Published: January 2020

4-Chlorobenzoate dehalogenase from Pseudomonas sp. strain CBS3 converted 4-chloro-3,5-dinitrobenzoate to 3,5-dinitro-4-hydroxybenzoate and 1-chloro-2,4-dinitrobenzene to 2,4-dinitrophenol. The activities were 0.13 mU/mg of protein for 4-chloro-3,5-dinitrobenzoate and 0.16 mU/mg of protein for 1-chloro-2,4-dinitrobenzene compared with 0.5 mU/mg of protein for 4-chlorobenzoate.
Effects of Stirring and Hydrogen on Fermentation Products of
Clostridium thermocellum
Authors: Lamed R. J. , Lobos J. H. , Su T. M.
Published: January 2020

Clostridium thermocellum
produces ethanol, acetate, H
2
, and CO
2
as major fermentation products from cellulose and cellobiose. The performance of three strains of this microorganism was studied to assess the potential use in producing ethanol directly from cellulosic fiber. Depending on the bacterial strain, an ethanol/acetate product ratio from 1 to as high as 3 was observed in unstirred cultures. Vigorous stirring during growth resulted in a threefold decrease in the ethanol/acetate ratio. The H
2
content in the unstirred culture broth was three times greater than that in the stirred one. Addition of exogenous H
2
to the gas phase during growth increased the ethanol/acetate ratio much more in the stirred than in the unstirred fermentations. The addition of sufficient H
2
to the gas phase almost relieved the effect of stirring, and the ethanol/acetate ratio approached that in the unstirred condition. Addition of tritium to the gas phase of the culture resulted in the formation of tritiated water (
3
H
2
O), which indicates that
C. thermocellum
possesses hydrogenase(s) that catalyzes the reverse reaction. The rate of
3
H
2
O formation was about three times higher in the stirred culture than in the unstirred culture. These results demonstrate that the H
2
concentration in the broth plays an important role in the product formation. The H
2
supersaturation present in the unstirred cultures is responsible for the observed effect of stirring. A hydrogen feedback control mechanism regulating the relative concentrations of reduced and oxidized electron carriers is proposed to account for the effect of hydrogen on the metabolite distribution.
Microbial degradation of n-alkyl tetrahydrothiophenes found in petroleum
Authors: Fedorak P M , Payzant J D , Montgomery D S , Westlake D W
Published: January 2020

Although n-alkyl-substituted tetrahydrothiophenes are found in nonbiodegraded petroleums, they are not found in petroleums which have undergone biodegradation in their reservoirs. These observations suggested that this group of compounds with alkyl chain lengths from approximately C10 to at least C30 is biodegradable. Two of these sulfides, 2-n-dodecyltetrahydrothiophene (DTHT) and 2-n-undecyltetrahydrothiophene, were synthesized, and their biodegradabilities were tested by using five gram-positive, n-alkane-degrading bacterial isolates. The alkyl side chains of these compounds were oxidized, and the major intermediates found in 2-n-undecyltetrahydrothiophene- and DTHT-metabolizing cultures were 2-tetrahydrothiophenecarboxylic acid (THTC) and 2-tetrahydrothiopheneacetic acid (THTA), respectively. Four n-alkane-degrading fungi were also shown to degrade DTHT, yielding both THTA and THTC. Quantitation of tetrahydrothiophene ring-containing products in 28-day-old bacterial and fungal cultures suggested that THTC and THTA were metabolized further to unidentified products. In addition, two of the bacterial isolates were shown to degrade a mixture of n-alkyl tetrahydrothiophenes isolated from Bellshill Lake crude oil.
Intergeneric Protoplast Fusion between
Ruminococcus albus
and an Anaerobic Recombinant, FE7
Authors: Chen Wei , Nagashima Kyo , Kajino Tsutomu , Ohmiya Kunio , Shimizu Shoichi
Published: January 2020

Intergeneric protoplast fusion between
Ruminococcus albus
, a cellulolytic, gram-positive, anaerobic bacterium (Pc
s
Sm
r
Km
s
), and an anaerobic recombinant, FE7 (Pc
r
Sm
s
Km
r
), having lignin-related compound-degrading activities, was performed under strictly anaerobic conditions to introduce cellulase genes into strain FE7. The fusion frequency varied with different selected markers from 3.0 × 10
−6
to 3.3 × 10
−7
. Two fusants, obtained from a synthetic medium with selective pressures of penicillin and streptomycin and with cellooli-gomer as the sole carbon source, were gram-negative rods. One of them, named FE7R2, showed 45 to 47% of the β-glucosidase and cellobiosidase activities of its parent
R. albus
and still maintained a level of degradation activity against dehydrodivanillin, a lignin-related compound, of up to 87% of that of the parent strain FE7. To verify that the cellulolytic activities expressed in the fusant FE7R2 originated from
R. albus
cellulase genes, the β-glucosidase gene of
R. albus
was cloned into
Escherichia coli
HB101 with plasmid pBR322. Cells bearing a recombinant plasmid, pRAII, produced high enzyme activities against both
p
-nitrophenyl-β-
d
-glucoside and
p
-nitrophenyl-β-
d
-cellobioside and could degrade cellobiose to glucose. Southern blot results showed that the cloned DNA fragment could hybridize with chromosomal DNAs of both
R. albus
and FE7R2, but did not with the chromosomal DNA of FE7, indicating that the β-glucosidase gene fragment was introduced into the chromosome of FE7R2 from
R. albus
via the protoplast fusion. The fusant FE7R2 could utilize simultaneously both cellobiose and dehydrodivanillin. These results gave evidence that the fusion product FE7R2 is a recombinant strain between its parents
R. albus
and FE7. This recombinant has stably kept the above properties for about 2 years.
Structure of an endo-beta-1,4-glucanase gene from Clostridium acetobutylicum P262 showing homology with endoglucanase genes from Bacillus spp
Authors: Zappe H , Jones W A , Jones D T , Woods D R
Published: January 2020

The nucleotide sequence of an endo-beta-1,4-glucanase gene of Clostridium acetobutylicum contained two putative extended promoter consensus sequences, a Shine-Dalgarno sequence and a TTG initiation codon. The nucleotide sequence of the gene coding for the C-terminal region of this enzyme was not required for activity. Extensive homology in the nucleotide and amino acid sequences of the endoglucanase genes from C. acetobutylicum and Bacillus spp. was demonstrated.
Degradation of the Phosphonate Herbicide Glyphosate by
Arthrobacter atrocyaneus
ATCC 13752
Authors: Pipke Rüdiger , Amrhein Nikolaus
Published: January 2020

Of nine authentic
Arthrobacter
strains tested, only
A. atrocyaneus
ATCC 13752 was capable of using the herbicide glyphosate [
N
-(phosphonomethyl)glycine] as its sole source of phosphorus. Contrary to the previously isolated
Arthrobacter
sp. strain GLP-1, which degrades glyphosate via sarcosine,
A. atrocyaneus
metabolized glyphosate to aminomethylphosphonic acid. The carbon of aminomethylphosphonic acid was entirely converted to CO
2
. This is the first report on glyphosate degradation by a bacterial strain without previous selection for glyphosate utilization as a source of phosphorus.
Selective stabilization by the bacteriophage 434 repressor of the plasmid expressing bovine growth hormone in Escherichia coli
Authors: Giladi H , Koby S , Oren R , Levanon A , Oppenheim A B
Published: January 2020

The maintenance of a plasmid vector-host system that selects for bacteria carrying the plasmid without the need for antibiotics is described. In this system, the bacteriophage 434 repressor gene cloned on the plasmid protects the host from lysis by a lambda imm434 cI- prophage. Cells that occasionally lose the plasmid are killed by prophage induction and therefore do not accumulate in the growing culture. The presence of the phage 434 repressor in the cells does not interfere with the process of lambda repressor inactivation and the high-level production of bovine growth hormone.
Continuous-sterilization system that uses photosemiconductor powders
Authors: Matsunaga T , Tomoda R , Nakajima T , Nakamura N , Komine T
Published: January 2020

We report a novel photochemical sterilization system in which Escherichia coli cells were sterilized with photosemiconductor powders (titanium oxide). For sterilization that could be used in practice, it was necessary to separate the TiO2 powders from the cell suspension. Therefore, semiconductor powders were immobilized on acetylcellulose membranes. We constructed a continuous-sterilization system consisting of a TiO2-immobilized acetylcellulose membrane reactor, a mercury lamp, and a masterflex pump. As a result, under the various sterilization conditions examined, E. coli (10(2) cells per ml) was sterilized to less than 1% survival when the cell suspension flowed in this system at a mean residence time of 16.0 min under irradiation (1,800 microeinsteins/m2 per s). We found that this system was reusable.
Transfer of conjugative plasmids and mobilization of a nonconjugative plasmid between Streptomyces strains on agar and in soil
Authors: Rafii F , Crawford D L
Published: January 2020

The conjugative plasmid pIJ101 and its conjugative nondeletion derivatives pIJ303 and pIJ211 were tested for their transferability between strains of Streptomyces on laboratory media and in the soil environment. Their roles in the mobilization of the cloning vector plasmid pIJ702, a nonconjugative deletion derivative of pIJ101, were also examined. Biparental and triparental crosses were performed on agar slants and in sterile soil between the plasmid donor Streptomyces lividans and several recipient Streptomyces strains previously isolated from soil. Conjugative plasmids were transferred to seven recipients in slant crosses and to three recipients in soil. Plasmids isolated from recipients showed restriction fragment patterns identical to that of the original plasmid in S. lividans. Plasmid pIJ303 was transferred less frequently in soil than on slants, and the frequency of transfer was higher at 30 degrees C than at the other temperatures examined. Transconjugant Streptomyces strains differed in their ability to maintain pIJ303. The nonconjugative plasmid pIJ702 was mobilized on agar slants into S. coelicolor 2708, which already contains a self-transmissible plasmid. Plasmid pIJ702 was also mobilized into S. flavovirens, Streptomyces sp. strain 87A, and S. parvulus on slants and in sterile soil after triparental crosses with two donors, one containing pIJ702 and the other containing either pIJ101 or pIJ211. The presence of a conjugative plasmid donor was required for the transfer of pIJ702 to S. parvulus 1234, S. flavovirens 28, and Streptomyces sp. strain 87A. Plasmid pIJ702 was always transferred in its normal, autonomous form. Chromosomal recombination also occurred in transconjugants after the transfer of pIJ702. This is the first report of gene transfer between Streptomyces strains in soil.
Effect of age and housing location on antibiotic resistance of fecal coliforms from pigs in a non-antibiotic-exposed herd
Authors: Langlois B E , Dawson K A , Leak I , Aaron D K
Published: January 2020

The relationship of age and housing location to single antibiotic resistance, multiple antibiotic resistance, and resistance patterns of fecal coliforms obtained during a 20-month period from pigs in a herd that was not exposed to antibiotics for 126 months was determined. Bacteria resistant to single and multiple antibiotics were isolated more frequently (P less than 0.01) from pigs under 7 months of age. A greater proportion of isolates from pigs over 6 months of age was sensitive to the 13 antimicrobial agents tested (P less than 0.01), while a smaller proportion showed resistance to single (P less than 0.05) and multiple (P less than 0.01) antibiotics. More than 80% of the resistant isolates were resistant to tetracycline, streptomycin, or sulfisoxazole. Resistance was greater (P less than 0.01) for pigs in the finishing unit than for those on pasture. Resistance to ampicillin, carbenicillin, and tetracycline was greater (P less than 0.05) for pigs in the finishing unit than for those in the farrowing house. More isolates from pigs on pasture were sensitive to all antimicrobial agents tested (P less than 0.01). A greater proportion of isolates from pigs in the finishing unit showed resistance to a single antibiotic (P less than 0.01). The data from this study suggest that exposure to antibiotics is not the only factor that influences the prevalence of bacteria that are resistant to single and multiple antibiotics in the feces of domestic animals and that considerable research is needed to define the factors influencing antibiotic resistance in fecal bacteria.
Bacterial metabolism of carbofuran
Authors: Chaudhry G R , Ali A N
Published: January 2020

Fifteen bacteria capable of degrading carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) were isolated from soil samples with a history of pesticide application. All isolates were gram negative and were oxidase- and catalase-positive rods; they occurred singly or as short chains. All of the identified isolates belonged to one of two genera, Pseudomonas and Flavobacterium. They were separated into three groups based on their mode of utilization of carbofuran. Six isolates were placed in group I; these isolates utilized carbofuran as a sole source of nitrogen. Seven isolates were placed in group II; these isolates utilized the pesticide as a sole source of carbon. Isolates of both groups I and II hydrolyzed carbofuran to carbofuran phenol. Two isolates, designated group III, also utilized carbofuran as a sole source of carbon. They degraded the pesticide more rapidly, however, so up to 40% of [14C]carbofuran was lost as 14CO2 in 1 h. The results suggest that these isolates degrade carbofuran by utilizing an oxidative pathway.
Evaluation of selective direct plating media for their suitability to recover uninjured, heat-injured, and freeze-injured Listeria monocytogenes from foods
Authors: Golden D A , Beuchat L R , Brackett R E
Published: January 2020

Six direct plating media were evaluated for their suitability to recover uninjured, heat-injured, and freeze-injured cells of four strains of Listeria monocytogenes from four foods. Cells were inoculated into foods to achieve ca. 10(2) to 10(3), 10(4) to 10(5), or 10(5) to 10(6) viable cells per ml or g (low, medium, and high populations, respectively). No appreciable differences in recovery of the four test strains within a treatment were observed. Generally, recovery on all test media was similar and not markedly affected by freeze treatment. Modified Despierres agar and modified McBride Listeria agar yielded poorer recovery of heat-injured cells than did McBride Listeria agar and gum base-nalidixic acid-tryptone soya agar. Overall, gum base-nalidixic acid-tryptone soya agar was best for recovering L. monocytogenes from pasteurized milk and chocolate ice cream mix. Enumeration was complicated by the growth of background microflora present in Brie cheese and cabbage, especially at the low inoculum. Dominguez Rodriguez isolation agar was superior for recovering L. monocytogenes from Brie cheese, whereas modified Despierres agar was best for recovering the organism from cabbage. Direct plating procedures can successfully be utilized for recovering healthy and injured L. monocytogenes from foods containing low populations of background microflora.
Toluene degradation by Pseudomonas putida F1: genetic organization of the tod operon
Authors: Zylstra G J , McCombie W R , Gibson D T , Finette B A
Published: January 2020

Pseudomonas putida PpF1 degrades toluene through cis-toluene dihydrodiol to 3-methylcatechol. The latter compound is metabolized through the well-established meta pathway for catechol degradation. The first four steps in the pathway involve the sequential action of toluene dioxygenase (todABC1C2), cis-toluene dihydrodiol dehydrogenase (todD), 3-methylcatechol 2,3-dioxygenase (todE), and 2-hydroxy-6-oxo-2,4-heptadienoate hydrolase (todF). The genes for these enzymes form part of the tod operon which is responsible for the degradation of toluene by this organism. A combination of transposon mutagenesis of the PpF1 chromosome, as well as analysis of cloned chromosomal fragments, was used to determine the physical order of the genes in the tod operon. The genes were determined to be transcribed in the order todF, todC1, todC2, todB, todA, todD, todE.
Cloning of
Trametes versicolor
Genes Induced by Nitrogen Starvation
Authors: Trudel Pierre , Courchesne Danièle , Roy Christian , Chartrand Pierre
Published: January 2020

We have screened a genomic library of
Trametes versicolor
for genes whose expression is associated with nitrogen starvation, which has been shown to induce ligninolytic activity. Using two different approaches based on differential expression, we isolated 29 clones. These were shown by restriction mapping and cross-hybridization to code for 11 distinct differentially expressed genes. Northern analysis of the kinetics of expression of these genes revealed that at least four of them have kinetics of induction that parallel kinetics of induction of ligninolytic activity.
Aerial Dispersal and Epiphytic Survival of
Pseudomonas syringae
during a Pretest for the Release of Genetically Engineered Strains into the Environment
Authors: Lindow Steven E. , Knudsen Guy R. , Seidler Ramon J. , Walter Michael V. , Lambou Victor W. , Amy Penny S. , Schmedding David , Prince Valerie , Hern Stephen
Published: January 2020

Prospective experimental field evaluation of genetically engineered microorganisms, such as microbial pest control agents, raises issues of how to properly ascertain their fate and survival in the environment. Field trials with recombinant organisms must reflect requirements for sampling and monitoring. Field trials were conducted at Tulelake, Calif., to monitor the numbers of viable cells of a nonrecombinant strain of
Pseudomonas syringae
that entered the atmosphere and landed on plants and soil during and after an aerosol spray application. An exponential decrease in numbers of viable cells deposited at increasing distances from three sprayed plots was observed. The relative rate of survival of cells sprayed directly on plants was more than 10 times higher than that of cells dispersed through the air to similar adjacent plants. Results are being used to gain experience with the characteristics of a release site that influence containment or dispersal and to develop appropriate sampling methodologies for evaluating survival and dispersal characteristics of genetically engineered bacteria released into the environment. The ability to make predictions about microbial dispersal and survival will reduce the uncertainties associated with environmental releases of recombinant organisms.
Isolation and characterization of a temperate bacteriophage from the ruminal anaerobe Selenomonas ruminantium
Authors: Lockington R A , Attwood G T , Brooker J D
Published: January 2020

A temperate bacteriophage was obtained from an isolate of the ruminal anaerobe Selenomonas ruminantium. Clear plaques that became turbid on further incubation occurred on a lawn of host bacteria. Cells picked from a turbid plaque produced healthy liquid cultures, but these often lysed on storage. Mid-log-phase liquid cultures incubated with the bacteriophage lysed and released infectious particles with a titer of up to 3 X 10(7) PFU/ml. A laboratory strain of S. ruminantium, HD-4, was also sensitive to this bacteriophage, which had an icosohedral head (diameter, 50 nm) and a flexible tail (length, 140 nm). The bacteriophage contained 30 kilobases of linear, double-stranded DNA, and a detailed restriction map was constructed. The lysogenic nature of infection was demonstrated by hybridization of bacteriophage DNA to specific restriction fragments of infected host genomic DNA and by identification of a bacteriophage genomic domain which may participate in integration of the bacteriophage DNA. Infection of S. ruminantium in vitro was demonstrated by two different methods of cell transformation with purified bacteriophage DNA.
Identification of an anthraquinone pigment and a hydroxystilbene antibiotic from Xenorhabdus luminescens
Authors: Richardson W H , Schmidt T M , Nealson K H
Published: January 2020

The entomopathogenic bacterium Xenorhabdus luminescens produces a red pigment and an antibiotic in insect carcasses in which it grows and in axenic cultures. The pigment was purified and identified as the anthraquinone derivative 1,6-dihydroxy-4-methoxy-9,10-anthraquinone, which exhibits a pH-sensitive color change, i.e., it is yellow below pH 9 and red above pH 9. The antibiotic was also purified and identified as the hydroxystilbene derivative 3,5-dihydroxy-4-isopropylstilbene.
Presence of aflatoxin M1 in commercial ultra-high-temperature-treated milk
Authors: Blanco J L , Domínguez L , Gómez-Lucía E , Garayzabal J F , García J A , Suárez G
Published: January 2020

Forty-seven samples of commercial ultra-high-temperature-treated milk from a dairy facility in the northwest part of Spain were analyzed for the presence of aflatoxin M1. A total of 14 samples (29.8%) were positive for aflatoxin M1 (4 in May, 3 in November, 3 in December, 1 in January, 1 in April, 1 in July, and 1 in August), 29 (61.7%) were negative, and 4 (8.5%) were doubtful, i.e., they showed trace quantities of aflatoxin M1. The range of aflatoxin M1 content was 0.02 to 0.1 ng/ml.
A Simple, Rapid Method for Enumerating Total Viable and Metabolically Active Bacteria in Groundwater
Authors: King Laura K. , Parker Bruce C.
Published: January 2020

We report here a new staining procedure which uses both the enzymatic dehydrogenation of 2-(
p
-iodophenyl)-3-
p
-(nitrophenyl)-5 phenyltetrazolium chloride to a pink intracellular formazan and the DNA-specific fluorochrome 4′,6′-diamidino-2-phenylindole. Application of this staining procedure to cells concentrated on filters and then transferred to microscope slides by the filter-transfer-freeze technique has proven valuable for statistically accurate enumeration of the total viable and metabolically active cells in groundwaters.
Seroepidemiology of cholera in Gulf coastal Texas
Authors: Hunt M D , Woodward W E , Keswick B H , Dupont H L
Published: January 2020

Single serum samples from 559 volunteers from a Texas Gulf Coast area were examined for vibriocidal antibody to Vibrio cholerae O1 (biotype El Tor, serotype Inaba) by a microtiter method. Elevated levels of vibriocidal antibody were present in 14% of the subjects. Also, 6.8% of the subjects had elevated levels of antibody to the enterotoxin of V. cholerae O1 by the immunoglobulin G enzyme-linked immunosorbent assay. Recent infection, defined on the basis of elevations in both vibriocidal and antitoxin antibodies, had occurred in 1.3% of the subjects. When subjects who reported Brucella infection, travel to a cholera-endemic area, and/or cholera vaccination within a year of the study were removed from the analysis, a prevalence of recent infection of 0.89% was obtained. Significantly higher titers of vibriocidal antibody were found in those with exposure to seawater (fishermen, shrimpers, merchant marines, and dock workers) than in those without such exposure (P less than 0.005). Furthermore, titers of antitoxin antibody were significantly higher in those who consumed shellfish than in nonconsumers. Finally, titers of vibriocidal antibody were significantly higher in Vietnamese subjects than in non-Vietnamese subjects. The results of this study indicate that an endemic focus of infection with V. cholerae occurs in this area.
Degradation of trichloroethylene by toluene dioxygenase in whole-cell studies with Pseudomonas putida F1
Authors: Wackett L P , Gibson D T
Published: January 2020

Toluene-induced cells of Pseudomonas putida F1 removed trichloroethylene from growth media at a significantly greater initial rate than the methanotroph Methylosinus trichosporium OB3b. With toluene-induced P. putida F1, the initial degradation rate varied linearly with trichloroethylene concentration over the range of 8 to 80 microM (1.05 to 10.5 ppm). At 80 microM (10.5 ppm) trichloroethylene and 30 degrees C, the initial rate was 1.8 nmol/min per mg of total cell protein, but the rate decreased rapidly with time. A series of mutant strains derived from P. putida F1 that are defective in the todC gene, which encodes the oxygenase component of toluene dioxygenase, failed to degrade trichloroethylene and to oxidize indole to indigo. A spontaneous revertant selected from a todC culture regained simultaneously the abilities to oxidize toluene, to form indigo, and to degrade trichloroethylene. The three isomeric dichloroethylenes were degraded by P. putida F1, but tetrachloroethylene, vinyl chloride, and ethylene were not removed from incubation mixtures.
Photoexcretion and Fate of Glycolate in a Hot Spring Cyanobacterial Mat
Authors: Bateson Mary M. , Ward David M.
Published: January 2020

Photosynthesis by
Synechococcus lividus
, the sole oxygenic phototroph inhabiting the surface of the 55°C cyanobacterial mat in Mushroom Spring, Yellowstone National Park, causes superoxic and alkaline conditions which promote glycolate photoexcretion. At O
2
concentrations characteristic of the top 2 mm of mat during the day, up to 11.8% of NaH
14
CO
3
fixed in the light was excreted, and glycolate accounted for up to 58% of the excreted photosynthate. Glycolate was neither incorporated nor metabolized by
S. lividus
, but it was incorporated by filamentous microorganisms in the mat. Incubation of mat samples with NaH
14
CO
3
resulted in labeling of both
S. lividus
and filaments, but the addition of nonradioactive glycolate increased the level of
14
C in the aqueous phase and decreased the extent of labeling of filaments. This suggests that cross-feeding of glycolate from
S. lividus
to filamentous heterotrophs occurs and that underestimation of the extent of photoexcretion is probable.
Novel method for purification of staphylococcal enterotoxin A
Authors: Reynolds D , Tranter H S , Sage R , Hambleton P
Published: January 2020

A novel single-step procedure for the purification of staphylococcal enterotoxin A (SEA), namely, dye ligand affinity chromatography with the triazine dye Red A, was developed. SEA purified by this method produced a single band when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The yield from 5 liters of culture supernatant was 0.113 g, corresponding to an overall yield of 55%. In some instances, purification of SEA from culture supernatants by dye ligand affinity chromatography produced two enterotoxin peaks that could be eluted from the column with 300 and 500 mM phosphate buffer (pH 6.8). Enterotoxin from these peaks produced a single band when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but multiple bands were observed on isoelectric focusing gels. This method of purification represents a significant improvement in time, yields, and purity of enterotoxin over previously published purification methods.
Melanin Production by
Rhizobium
Strains
Authors: Cubo M. Teresa , Buendia-Claveria Ana M. , Beringer John E. , Ruiz-Sainz José E.
Published: January 2020

Different
Rhizobium
and
Bradyrhizobium
strains were screened for their ability to produce melanin. Pigment producers (Mel
+
) were found among strains of
R. leguminosarum
biovars
viceae, trifolii
, and
phaseoli, R. meliloti
, and
R. fredii
; none of 19
Bradyrhizobium
strains examined gave a positive response. Melanin production and
nod
genes were plasmid borne in
R. leguminosarum
biovar
trifolii
RS24. In
R. leguminosarum
biovar
phaseoli
CFN42 and
R. meliloti
GR015,
mel
genes were located in the respective symbiotic plasmids. In
R. fredii
USDA 205, melanin production correlated with the presence of its smallest indigenous plasmid.
Fluorescein Isothiocyanate-Labeled Lectin Analysis of the Surface of the Nitrogen-Fixing Bacterium
Azospirillum brasilense
by Flow Cytometry
Authors: Yagoda-Shagam Janet , Barton Larry L. , Reed William P. , Chiovetti Robert
Published: January 2020

The cell surface of
Azospirillum brasilense
was probed by using fluorescein isothiocyanate (FITC)-labeled lectins, with binding determined by fluorescence-activated flow cytometry. Cells from nitrogen-fixing or ammonium-assimilating cultures reacted similarly to FITC-labeled lectins, with lectin binding in the following order:
Griffonia simplicifolia
II agglutinin >
Griffonia simplicifolia
I agglutinin >
Triticum vulgaris
agglutinin >
Glycine max
agglutinin >
Canavalia ensiformis
agglutinin >
Limax flavus
agglutinin >
Lotus tetragonolobus
agglutinin. The fluorescence intensity of cells labeled with FITC-labeled
G. simplicifolia
I,
C. ensiformis, T. vulgaris
, and
G. max
agglutinins was influenced by lectin concentration. Flow cytometry measurements of lectin binding to cells was consistent with measurements of agglutination resulting from lectin-cell interaction. Capsules surrounding nitrogen-fixing and ammonium-assimilating cells were readily demonstrated by light and transmission electron microscopies.
Fundamental Procedures for Determining Ergosterol Content of Decaying Plant Material by Liquid Chromatography
Authors: Newell S. Y. , Arsuffi T. L. , Fallon R. D.
Published: January 2020

Portions of published procedures for measurement of ergosterol content of decomposing plants were examined for their influence upon ergosterol yield. Common methods of treatment of plant samples prior to sterol extraction (e.g., oven drying, freezing, lyophilization) led to reduced recoveries of ergosterol (ca. 20 to 80%). The least destructive method was direct placement and storage in methanol. Photoconversion of ergosterol is not likely to cause losses during analysis, but losses are likely if there is insufficient mixing during neutral-lipid partitioning from base-hydrolysis reagents. Homogenization (two times for 2 min) and refluxing (2 h) in methanol were equally effective in extracting ergosterol. Direct extraction in base-hydrolysis reagents was less effective (by ca. 40%).
Conjugal transfer of R68.45 and FP5 between Pseudomonas aeruginosa strains in a freshwater environment
Authors: O'Morchoe S B , Ogunseitan O , Sayler G S , Miller R V
Published: January 2020

Recent concern over the release of genetically engineered organisms has resulted in a need for information about the potential for gene transfer in the environment. In this study, the conjugal transfer in Pseudomonas aeruginosa of the plasmids R68.45 and FP5 was demonstrated in the freshwater environment of Fort Loudoun Resevoir, Knoxville, Tenn. When genetically well defined plasmid donor and recipient strains were introduced into test chambers suspended in Fort Loudoun Lake, transfer of both plasmids was observed. Conjugation occurred in both the presence and absence of the natural microbial community. The number of transconjugants recovered was lower when the natural community was present. Transfer of the broad-host-range plasmid R68.45 to organisms other than the introduced recipient was not observed in these chambers but was observed in laboratory simulations when an organism isolated from lakewater was used as the recipient strain. Although the plasmids transferred in laboratory studies were genetically and physically stable, a significant number of transconjugants recovered from the field trials contained deletions and other genetic rearrangements, suggesting that factors which increase gene instability are operating in the environment. The potential for conjugal transfer of genetic material must be considered in evaluating the release of any genetically engineered microorganism into a freshwater environment.
Cometabolism of polychlorinated biphenyls: enhanced transformation of Aroclor 1254 by growing bacterial cells
Authors: Kohler H P , Kohler-Staub D , Focht D D
Published: January 2020

Acinetobacter sp. strain P6 and a soil isolate, Arthrobacter sp. strain B1B, were tested for their ability to transform Aroclor 1254 as washed resting cells and as growing cells with biphenyl as the substrate. Growing cells were far superior to resting-cell suspensions in terms of total polychlorinated biphenyl (PCB) transformation, transformation of specific PCB congeners, and diversity of congeners that were attacked. Growing cells of Acinetobacter sp. strain P6 and Arthrobacter sp. strain B1B transformed 32 and 23% of the [14C]Aroclor 1254, respectively, whereas resting cells of the same respective cultures transformed only 17 and 8%. Transformation was significantly greater with resting cells in only 2 of 39 cases in which congeners were transformed by both growing and resting cells of both cultures. The components of 19 and 12 capillary gas-chromatographic peaks of Aroclor 1254 were transformed by biphenyl-grown resting cells of Acinetobacter sp. strain P6 and Arthrobacter sp. strain B1B, respectively, whereas the components of an additional 6 and 7 peaks were attacked by growing cells of the same respective cultures. Biphenyl oxidation by resting cells of both cultures decreased with time to less than 8% in 28 h. In addition to the normal 2,3-dioxygenase attack on PCBs, Acinetobacter sp. strain P6 also attacked congeners lacking an open 2,3-position. The ability of Acinetobacter sp. strain P6 to transform the components of 25 of the 40 largest peaks of Aroclor 1254 makes it one of the most versatile PCB-transforming organisms yet reported.
Coaggregation properties of human oral Veillonella spp.: relationship to colonization site and oral ecology
Authors: Hughes C V , Kolenbrander P E , Andersen R N , Moore L V
Published: January 2020

The primary habitats of oral veillonellae are the tongue, dental plaque, and the buccal mucosa. Isolates were obtained from each habitat and tested for coaggregation with a battery of other oral bacterial strains. All 59 tongue isolates tested for coaggregation were Veillonella atypica or Veillonella dispar. All but one of them coaggregated with strains of Streptococcus salivarius, a predominant inhabitant of the tongue surface but not subgingival dental plaque. These tongue isolates were unable to coaggregate with most normal members of the subgingival flora such as Actinomyces viscosus, Actinomyces naeslundii, Actinomyces israelii, and Streptococcus sanguis. In contrast, 24 of 29 Veillonella isolates, of which 20 were Veillonella parvula from subgingival dental plaque samples, coaggregated strongly with the three species of Actinomyces, S. sanguis, and other bacteria usually present in subgingival plaque, but they did not coaggregate with S. salivarius. The majority of isolates from the buccal mucosa (42 of 55) has coaggregation properties like those from the tongue. These results indicate that the three human oral Veillonella species are distributed on oral surfaces that are also occupied by their coaggregation partners and thus provide strong evidence that coaggregation plays a critical role in the bacterial ecology of the oral cavity.
A deletion in the chromosome of Bacteroides thetaiotaomicron that abolishes production of chondroitinase II does not affect survival of the organism in gastrointestinal tracts of exgermfree mice
Authors: Salyers A A , Guthrie E P
Published: January 2020

Bacteroides thetaiotaomicron, an obligate anaerobe normally found in high concentrations in the human colon, is one of the few colon bacteria that can ferment host mucopolysaccharides such as chondroitin sulfate. Previously, we found that a directed insertional mutation in the gene that codes for the chondroitinase II gene of B. thetaiotaomicron did not affect growth on chondroitin sulfate despite the fact that chondroitinase II accounts for 70% of the total cellular chondroitinase activity. Thus, the chondroitinase II gene did not seem to contribute significantly to growth on chondroitin sulfate when the bacteria were grown in laboratory medium. To determine whether this enzyme is important for bacteria growing in the intestinal tract, we tested the ability of a strain that does not produce chondroitinase II to colonize the intestinal tracts of germfree mice and to compete with wild-type B. thetaiotaomicron. The mutant used in these experiments carried a 0.5-kilobase deletion in the chondroitinase II gene and was constructed so that, unlike the original insertion mutant, it contained no exogenous DNA. The deletion mutant colonized the intestinal tracts of germfree mice at the same levels as the wild type. When a mixture of the deletion mutant and wild type was used to colonize germfree mice, the percent wild type, measured by colony hybridization with the deleted 0.5-kilobase fragment as the hybridization probe, did not rise to 100% even after periods as long as 9 weeks. In most experiments, the percent wild type did not rise significantly above the percent in the original mixture.(ABSTRACT TRUNCATED AT 250 WORDS)
Early Infection and Competition for Nodulation of Soybean by
Bradyrhizobium japonicum
123 and 138
Authors: Zdor Robert E. , Pueppke Steven G.
Published: January 2020

Interactions of soybean with
Bradyrhizobium japonicum
123 (serogroup 123) and 138 (serogroup c1) were used to examine the relationship between early infection rates, competition for nodulation, and patterns of nodule occupancy. Both strains formed more infections in autoclaved soil (sterile soil) than in untreated soil (unsterile soil). Inoculation did not increase numbers of infection threads in unsterile soil-grown plants, where infection of proximal portions of primary roots was complete by 5 days after planting. Both strains infected and nodulated at similar rates in sterile soil. Nodules were always clustered on the upper root system, regardless of inoculation and soil treatment. Sixty-seven percent of the nodules of uninoculated plants grown in unsterile soil were occupied by rhizobia belonging to serogroups other than 123 or c1. Inoculation with strain 123 or 138 increased occupancy by that strain at the expense of residency by other rhizobia. Eighty-three percent of all nodules on plants dually inoculated with both strains in sterile soil contained strain 138. The corresponding value for plants inoculated in unsterile soil was 31%. Neither inoculum strain dominated occupancy of first-formed nodules in unsterile soil. It appears that north central Missouri soil may not have populations of highly competitive serogroup 123 and that early infection and nodulation rates do not contribute to the competitive success of strain 138.
Monoclonal Antibody Analysis and Insecticidal Spectrum of Three Types of Lepidopteran-Specific Insecticidal Crystal Proteins of
Bacillus thuringiensis
Authors: Höfte Herman , Van Rie Jeroen , Jansens Stefan , Van Houtven Annemie , Vanderbruggen Hilde , Vaeck Mark
Published: January 2020

We have investigated the protein composition and the insecticidal spectrum of crystals of 29
Bacillus thuringiensis
strains active against lepidopteran larvae. All crystals contained proteins of 130 to 140 kilodaltons (kDa) which could be grouped into three types by the molecular weight of the protoxin and the trypsin-activated core fragment. Proteins of the three types showed a characteristic insecticidal spectrum when tested against five lepidopteran species. Type A crystal proteins were protoxins of 130 or 133 kDa, which were processed into 60-kDa toxins by trypsin. Several genes encoding crystal proteins of this type have been cloned and sequenced earlier. They are highly conserved in the N-terminal half of the toxic fragment and were previously classified in three subtypes (the 4.5-, 5.3-, and 6.6-kilobase subtypes) based on the restriction map of their genes. The present study shows that different proteins of these three subtypes were equally toxic against
Manduca sexta
and
Pieris brassicae
and had no detectable activity against
Spodoptera littoralis
. However, the 4.5-, 5.3-, and 6.6-kilobase subtypes differed in their toxicity against
Heliothis virescens
and
Mamestra brassicae
. Type B crystal proteins consisted of 140-kDa protoxins with a 55-kDa tryptic core fragment. These were only active against one of the five insect species tested (
P. brassicae
). The protoxin and the trypsin-activated toxin of type C were 135- and 63-kDa proteins, respectively. Proteins of this type were associated with high toxicity against
S. littoralis
and
M. brassicae
. A panel of 35 monoclonal antibodies was used to compare the structural characteristics of crystal proteins of the three different types and subtypes. Each type of protein could be associated with a typical epitope structure, indicating an unambiguous correlation between antigenic structure and insect specificity.
Glycyrrhizin stimulates growth of Eubacterium sp. strain GLH, a human intestinal anaerobe
Authors: Akao T , Akao T , Kobashi K
Published: January 2020

Eubacterium sp. strain GLH was isolated from human feces and produced two kinds of beta-D-glucuronidase (EC 3.2.1.31), one new enzyme specific for glycyrrhizin (GL) and the other for phenyl beta-D-glucuronides. GL or p-nitrophenyl-mono-beta-D-glucuronide (pNPG) stimulated the production of GL or pNPG beta-glucuronidases and the growth of strain GLH in a basal medium lacking carbohydrate. D-Glucuronic acid also stimulated the growth of the bacterium, but glycyrrhetic acid did not. The increase of GL beta-glucuronidase paralleled the growth of the Eubacterium strain in pure culture. These results suggest that glucuronides such as GL and pNPG stimulate the growth of the Eubacterium strain in a nutrient-poor medium by providing D-glucuronic acid through the activity of beta-glucuronidases. The increase in GL beta-glucuronidase activity in the presence of GL was observed during the cultivation of human intestinal flora in a general anaerobic medium. During mixed cultivation of the Eubacterium strain with Streptococcus faecalis, which does not produce GL beta-glucuronidase, GL beta-glucuronidase was also increased by GL or pNPG, but not by glycyrrhetic acid and p-nitrophenol. It is suggested that GL stimulates the growth of strain GLH even in the mixed culture.
Activation of Clostridium perfringens spores under conditions that disrupt hydrophobic interactions of biological macromolecules
Authors: Craven S E
Published: January 2020

The effect of hydrophobic interactions on the activation of C. perfringens NCTC 8679 spores was examined by heating spores under conditions that modify the hydrophobic properties of biological macromolecules. After the activation treatment and a washing procedure, germination was determined by measuring the decrease in optical density of spores suspended in an enriched germination medium. Activation was inhibited for spores that were treated under conditions that strengthen hydrophobic interactions, i.e., a decrease in pH or the presence of structure-stabilizing neutral salts. Activation was enhanced by treatment under conditions that disrupt hydrophobic interactions, i.e., an increase in pH or the presence of urea, dibucaine, or denaturing neutral salts. A deactivation treatment with the antichaotropic salt (NH4)2SO4 reversed activation by the chaotropic salt CaCl2 and to a lesser extent reversed activation by sublethal heat (75 degrees C) or urea. Most treatments that enhanced activation increased spore injury at higher temperatures, which resulted in decreased germination. However, (NH4)2SO4 and a decrease in pH from 5.6 to 3.8, which inhibited activation, also favored injury. The results suggest that activation involves a conformational change of a spore protein(s) through weakening of hydrophobic molecular forces and that activation and injury occur at different spore sites.