bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular cloning of a xylanase gene from Bacteroides succinogenes and its expression in Escherichia coli
Authors: Sipat A , Taylor K A , Lo R Y , Forsberg C W , Krell P J
Published: January 2020

A gene coding for xylanase synthesis in Bacteroides succinogenes was isolated by cloning, with Escherichia coli HB101 as the host. After partial digestion of B. succinogenes DNA with Sau3A, fragments were ligated into the BamHI site of pBR322 and transformed into E. coli HB101. Of 14,000 colonies screened, 4 produced clear halos on Remazol brilliant blue-xylan agar. Plasmids from two stable clones recovered exhibited identical restriction enzyme patterns, with the same 9.4-kilobase-pair (kbp) insert. The plasmid was designated pBX1. After subcloning of restriction enzyme fragments, a 3-kbp fragment was found to code for xylanase activity in either orientation when inserted into pUC18 and pUC19. The original clone possessed approximately 10-fold higher xylanase activity than did clones harboring the 3-kbp insert in pUC18, pUC19, or pBR322. The enzyme was partially secreted into the periplasmic space of E. coli. The periplasmic enzyme of the BX1 clone had 2% of the activity on carboxymethyl cellulose and less than 0.2% of the activity on p-nitrophenyl xyloside and a range of other substrates that it exhibited on xylan. The xylanase gene was not subject to catabolite repression by glucose or induction by either xylan or xylose. The xylanase activity migrated as a single broad band on nondenaturing polyacrylamide gels. The Km of the pBX1-encoded enzyme was 0.22% (wt/vol) of xylan, which was similar to that for the xylanase activity in an extracellular enzyme preparation from B. succinogenes. Based on these data it appears that the xylanase gene expressed in E. coli is fully functional and codes for an enzyme with properties similar to the B. succinogenes enzyme(s).
Applicability of Yeast Extracellular Proteinases in Brewing: Physiological and Biochemical Aspects
Authors: Bilinski Carl A. , Russell Inge , Stewart Graham G.
Published: January 2020

A general screening survey for expression of extracellular acid proteinase production was performed on over 100 cultures belonging to the genus
Saccharomyces.
Although two strains of
Saccharomyces cerevisiae
showed positive extracellular proteinase phenotypes in plate tests, it was not possible to demonstrate proteolytic activities in cell-free culture supernatants in assays performed at beer pH values. Of several yeasts from other genera examined,
Saccharomycopsis fibuligera
and
Torulopsis magnoliae
produced extracellular proteinases with desirable properties. Proteolytic activities were detected in assays performed at beer pH values and at lower temperature. Brewer's wort served as a highly inducing medium for extracellular proteinase production, with
T. magnoliae
yielding enzyme of highest specific activity. In fact, commencement of enzyme production was detected shortly after the onset of exponential growth in brewer's wort. Inclusion of crude enzyme preparations in brewer's wort inoculated simultaneously with brewer's yeast reduced final ethanol yields slightly and was found to be effective in reducing chill haze formation in bottled beer.
Enterococcus faecalis hemolysin-bacteriocin plasmids belong to the same incompatibility group
Authors: Colmar I , Horaud T
Published: January 2020

Plasmid pair coexistence was studied both among nine Enterococcus faecalis hemolysin-bacteriocin (Hly-Bcn) plasmids, including pJH2, pAD1, pAM gamma 1, and pIP964, and between pIP964 and five R plasmids. Some of the Hly-Bcn plasmids used were derivatives encoding resistance to erythromycin or tetracycline. The Hly-Bcn plasmids were incompatible with each other; 40 to 100% displacement was observed bilaterally for eight pairs and unilaterally for one pair. In contrast, pIP964 stably coexisted with each of the R plasmids. Entry exclusion was associated with incompatibility for most of the Hly-Bcn plasmids. The nine Hly-Bcn plasmids harbored by E. faecalis form a distinct incompatibility (Inc) group, designated IncHly.
T-2 toxin metabolism by ruminal bacteria and its effect on their growth
Authors: Westlake K , Mackie R I , Dutton M F
Published: January 2020

The effect of T-2 toxin on the growth rates of different bacteria was used as a measure of its toxicity. Toxin levels of 10 micrograms/ml did not decrease the growth rate of Selenomonas ruminantium and Anaerovibrio lipolytica, whereas the growth rate of Butyrivibrio fibrisolvens was uninhibited at toxin levels as high as 1 mg/ml. There was, however, a noticeable increase in the growth rate of B. fibrisolvens CE46 and CE51 and S. ruminantium in the presence of low concentrations (10 micrograms/ml) of T-2 toxin, which may indicate the assimilation of the toxin as an energy source by these bacteria. Three tributyrin-hydrolyzing bacterial isolates did not grow at all in the presence of T-2 toxin (10 micrograms/ml). The growth rate of a fourth tributyrin-hydrolyzing bacterial isolate was unaffected. B. fibrisolvens CE51 degraded T-2 toxin to HT-2 toxin (22%), T-2 triol (3%), and neosolaniol (10%), whereas A. lipolytica and S. ruminantium degraded the toxin to HT-2 toxin (22 and 18%, respectively) and T-2 triol (7 and 10%, respectively) only. These results have been explained in terms of the presence of two different toxin-hydrolyzing enzyme systems. Studies with B. fibrisolvens showed the presence of a T-2 toxin-degrading enzyme fraction in a bacterial membrane preparation. This fraction had an approximate molecular weight of 65,000 and showed esterase activity (395.6 mumol of p-nitrophenol formed per min per mg of protein with p-nitrophenylacetate as the substrate.
Sensitivity of genetically engineered organisms to selective media
Authors: Lechevallier M W , Camper A K , Broadaway S C , Henson J M , McFeters G A
Published: January 2020

Eighteen strains of Escherichia coli used in genetic studies were tested for their ability to grow on several selective media. Highest recoveries were obtained with m-T7 agar. The SOS system, particularly the recA gene, may play some role in the sensitivity of E. coli to selective agents. These results may be important in the selection of media used to detect genetically engineered organisms released into the environment.
Antifungal activity of ajoene derived from garlic
Authors: Yoshida S , Kasuga S , Hayashi N , Ushiroguchi T , Matsuura H , Nakagawa S
Published: January 2020

The antifungal activity of six fractions derived from garlic was investigated in an in vitro system. Ajoene had the strongest activity in these fractions. The growth of both Aspergillus niger and Candida albicans was inhibited by ajoene at less than 20 micrograms/ml.
Immersible probe for continual monitoring of the population density of microorganisms grown in liquid media
Authors: Maxwell G M , Allen E R , Freese E
Published: January 2020

A common technique of measuring population density of microorganisms grown in liquid media is to withdraw a sample of the suspension and measure its apparent optical density with a spectrophotometer. The device we describe is capable of continually and automatically monitoring the population density of microorganisms grown in suspension.
Fate of viruses in artificial wetlands
Authors: Gersberg R M , Lyon S R , Brenner R , Elkins B V
Published: January 2020

Little is known about the ability of wetlands to remove disease-causing viruses from municipal wastewater. In this study we examined the survival of several indicators of viral pollution (indigenous F-specific bacteriophages, seeded MS2 bacteriophage, and seeded human poliovirus type 1) applied in primary municipal wastewater to artificial wetland ecosystems. Only about 1% of the indigenous F-specific RNA bacteriophages survived flow through the vegetated wetland beds at a 5-cm-day-1 hydraulic application rate during the period from June through December 1985. The total number of indigenous F-specific bacteriophages (F-specific RNA and F-specific DNA phages) was also reduced by about 99% by wetland treatment, with the mean inflow concentration over the period of an entire year reduced from 3,129 to 33 PFU ml-1 in the outflow of a vegetated bed and to 174 PFU ml-1 in the outflow of an unvegetated bed. Such superior treatment by the vegetated bed demonstrates the significant role of higher aquatic plants in the removal process. Seeded MS2 bacteriophage and seeded poliovirus were removed more efficiently than were the indigenous bacteriophages, with less than 0.2% of MS2 and 0.1% of the poliovirus surviving flow at the same hydraulic application rate. The decay rate (k) of MS2 in a stagnant wetlands (k = 0.012 to 0.028 h-1) was lower than that for flowing systems (k = 0.44 to 0.052 h-1), reflecting the enhanced capacity for filtration or adsorption of viruses by the root-substrate complex (and associated biofilm).(ABSTRACT TRUNCATED AT 250 WORDS)
Protein degradation by ruminal microorganisms from sheep fed dietary supplements of urea, casein, or albumin
Authors: Wallace R J , Broderick G A , Brammall M L
Published: January 2020

Ruminal fluid from sheep fed hay plus concentrate diets containing 1.8% urea, 6% casein, or 6% egg albumin had proteolytic activities of 4.12, 3.02, or 4.00 mg of [14C]casein hydrolyzed ml-1 h-1, respectively. Dietary albumin had no effect on the rate of albumin breakdown relative to that of casein (0.06). Greater numbers of highly proteolytic bacteria, mainly Butyrivibrio spp., were isolated from the rumens of sheep receiving albumin. Albumin hydrolysis by these isolates was even slower relative to that of casein (0.03) than in ruminal fluid and was similar to that found in isolates from urea- and casein-fed sheep. Hence, there appears to be no mechanism by which ruminal bacteria can alter their proteolytic activity to utilize resistant soluble protein more effectively.
Isolation and Characterization of a
Bacillus cereus
Mutant Strain Hyperproductive of Exo-β-Amylase
Authors: Nanmori Takashi , Numata Yoshinori , Shinke Ryu
Published: January 2020

Starting with a strain of
Bacillus cereus
excreting about 40-fold more β-amylase than does the original wild-type strain, we isolated, after mutagenesis with
N
-methyl-
N′
-nitro-
N
-nitrosoguanidine, a strain designated BQ10-S1 SpoIII which showed under optimal conditions a further 5.5-fold increase in β-amylase activity. The amylase production of this strain was observed to increase in the presence of 0.5% glucose or 1% maltose and, more markedly, in the presence of 2% soluble starch in the culture medium. The enzyme produced by this strain was immunologically identical to the wild-type enzyme, suggesting that either the copy number of the gene or the efficiency of enzyme synthesis from it, or both, are altered in this strain.
Tremorgenic mycotoxins from Aspergillus fumigatus as a possible occupational health problem in sawmills
Authors: Land C J , Hult K , Fuchs R , Hagelberg S , Lundström H
Published: January 2020

Wood-trimmers' disease, generally called extrinsic allergic alveolitis, which affects workers in sawmills, is thought to be caused by fungal diaspores. The importance of Aspergillus fumigatus on the surface of wood dried in kilns is accentuated by its ability to produce tremorgenic mycotoxins. Eight strains of A. fumigatus from five different sawmills were isolated and cultivated on liquid media, and one of the strains was also cultivated on wood blocks. Extracts were prepared, and the tremorgenic reactions were induced by oral administration of extracts to rats. Extracts of the strain grown in liquid medium and on wood blocks induced very strong tremorgenic reactions when administered orally to rats. Four other strains induced mild tremorgenic reactions. High-performance liquid chromatography analysis revealed two tremorgenic mycotoxins, verruculogen and fumitremorgen C, in the five toxic strains. One nontoxic strain produced detectable levels of verruculogen. These results, coupled with the known resemblance of the acutely toxic phase of wood-trimmers' disease to the symptoms produced by these tremorgens, imply that wood-trimmers' disease and similar occupational diseases are, at least in part, mycotoxicoses.
Antigenic characterization of Penicillium camemberti and related common cheese contaminants
Authors: Polonelli L , Morace G , Rosa R , Castagnola M , Frisvad J C
Published: January 2020

Twenty-four isolates of Penicillium (including a green-spored mutant from a French Brie cheese, Penicillium camemberti) with a proposed relationship to the white cheese mold P. camemberti were investigated by immunological procedures. These penicillia, which are representative of species that have caused considerable taxonomic confusion, had common micromorphology (terverticillate penicilli with rough and smooth stipes and smooth ellipsoidal to subglobose [(3 to 5) X 2 1/2 to 4 1/2 microns] conidia); growth rates; good growth on creatine sucrose agar, cheese, and other products with a high amount of protein and lipid as a primary habitat; production (with the exception of Penicillium solitum) of cyclopiazonic acid; and the ability to grow at low temperatures and water activities. The isolates that were investigated proved to be strictly antigenically related. Absorbed antiserum of the green-spored mutant of P. camemberti showed a specific precipitin band when tested by immunodiffusion either with its homologous reference antigen or with the exoantigens obtained from different isolates. The precipitin band was not present in any P. camemberti starter culture but in many unwanted cheese contaminants. The precipitin band can be used in the purity control of P. camemberti starter culture spore preparations. Analysis of the exoantigens of all the cultures by reversed phase high-performance liquid chromatography allowed us to subdivide these penicillia into nine groups below the species level. The results indicate that P. commune Thom is the wild-type ancestor of P. camemberti.
Reductive inactivation of digitoxin by Eubacterium lentum cultures
Authors: Chandrasekaran A , Robertson L W , Reuning R H
Published: January 2020

The obligate anaerobe Eubacterium lentum inactivated the cardiac glycoside digitoxin by reducing the double bond in the lactone ring. This conversion was quantitative when the substrate was incubated at a concentration of 10 micrograms/ml. The reduction reaction coincided with the growth phase of the bacterium. The stereochemical configuration at C-20 of the reduction product dihydrodigitoxin was found to be R. Incubation of digitoxigenin and its mono- and bisdigitoxosides individually with E. lentum led to the formation of their respective dihydro derivatives. The configuration at C-20 of these reduced metabolites was also found to be R.
Identification of O-methylsterigmatocystin as an aflatoxin B1 and G1 precursor in Aspergillus parasiticus
Authors: Bhatnagar D , McCormick S P , Lee L S , Hill R A
Published: January 2020

An isolate of Aspergillus parasiticus CP461 (SRRC 2043) produced no detectable aflatoxins, but accumulated O-methylsterigmatocystin (OMST). When sterigmatocystin (ST) was fed to this isolate in a low-sugar medium, there was an increase in the accumulation of OMST, without aflatoxin synthesis. When radiolabeled [14C]OMST was fed to resting mycelia of a non-aflatoxin-, non-ST-, and non-OMST-producing mutant of A. parasiticus AVN-1 (SRRC 163), 14C-labeled aflatoxins B1 and G1 were produced; 10 nmol of OMST produced 7.8 nmol of B1 and 1.0 nmol of G1, while 10 nmol of ST produced 6.4 nmol of B1 and 0.6 nmol of G1. A time course study of aflatoxin synthesis in ST feeding experiments with AVN-1 revealed that OMST is synthesized by the mold during the onset of aflatoxin synthesis. The total amount of aflatoxins recovered from OMST feeding experiments was higher than from experiments in which ST was fed to the resting mycelia. These results suggest that OMST is a true metabolite in the aflatoxin biosynthetic pathway between sterigmatocystin and aflatoxins B1 and G1 and is not a shunt metabolite, as thought previously.
Alternative nonlinear model for estimating second-order rate coefficients for biodegradation
Authors: Suflita J M , Smolenski W J , Robinson J A
Published: January 2020

A modification of the second-order model for biodegradation was derived, applied to an example data set, and shown to be superior for describing the anaerobic biodegradation of p-cresol by an enriched bacterial consortium. The modified model circumvents the no-growth assumption implicit in the use of the second-order rate equation, but still requires the assumption of first-order kinetics over the course of substrate depletion. Violation of the no-growth assumption is particularly important since overestimates of the pseudo-first-order rate coefficient lead to underestimates of the time required for the removal of a xenobiotic chemical from a contaminated environment. Our calculations show that the errors introduced into the pseudo-first-order rate coefficient (and the resulting estimates of the second-order rate coefficient) approach 100% if one doubling occurs in activity over the course of substrate depletion. For an exemplary data set, use of a first-order model resulted in a 100% overestimate of the first-order decay coefficient, which would in turn lead to a corresponding overestimate of the second-order rate coefficient. The modified model we describe is a potential alternative to the pseudo-first-order model for the routine estimation of second-order rate coefficients.
Oxygen-Poor Microzones as Potential Sites of Microbial N
2
Fixation in Nitrogen-Depleted Aerobic Marine Waters
Authors: Paerl Hans W. , Prufert Leslie E.
Published: January 2020

The nitrogen-deficient coastal waters of North Carolina contain suspended bacteria potentially able to fix N
2
. Bioassays aimed at identifying environmental factors controlling the development and proliferation of N
2
fixation showed that dissolved organic carbon (as simple sugars and sugar alcohols) and particulate organic carbon (derived from
Spartina alterniflora
) additions elicited and enhanced N
2
fixation (nitrogenase activity) in these waters. Nitrogenase activity occurred in samples containing flocculent, mucilage-covered bacterial aggregates. Cyanobacterium-bacterium aggregates also revealed N
2
fixation. In all cases bacterial N
2
fixation occurred in association with surficial microenvironments or microzones. Since nitrogenase is oxygen labile, we hypothesized that the aggregates themselves protected their constituent microbes from O
2
. Microelectrode O
2
profiles revealed that aggregates had lower internal O
2
tensions than surrounding waters. Tetrazolium salt (2,3,5-triphenyl-3-tetrazolium chloride) reduction revealed that patchy zones existed both within microbes and extracellularly in the mucilage surrounding microbes where free O
2
was excluded. Triphenyltetrazolium chloride reduction also strongly inhibited nitrogenase activity. These findings suggest that N
2
fixation is mediated by the availability of the appropriate types of reduced microzones. Organic carbon enrichment appears to serve as an energy and structural source for aggregate formation, both of which were required for eliciting N
2
fixation responses of these waters.
Extensive degradation of Aroclors and environmentally transformed polychlorinated biphenyls by Alcaligenes eutrophus H850
Authors: Bedard D L , Wagner R E , Brennan M J , Haberl M L , Brown J F
Published: January 2020

We have isolated and characterized a strain of Alcaligenes eurtrophus, designated H850, that rapidly degrades a broad and unusual spectrum of polychlorinated biphenyls (PCBs) including many tetra- and pentachlorobiphenyls and several hexachlorobiphenyls. This strain, which was isolated from PCB-containing dredge spoils by enrichment on biphenyl, grows well on biphenyl and 2-chlorobiphenyl but poorly on 3- and 4-chlorobiphenyl. Capillary gas-chromatographic analysis showed that biphenyl-grown resting cells of H850 degraded the components of 38 of the 41 largest peaks of Aroclor 1242 and 15 of the 44 largest peaks of Aroclor 1254, resulting in an overall reduction of PCBs by 81% for Aroclor 1242 (10 ppm) and 35% for Aroclor 1254 (10 ppm) in 2 days. Furthermore, H850 metabolized the predominantly ortho-substituted PCB congeners that resulted from the environmental transformation of the more highly chlorinated congeners of Aroclor 1242 by the upper Hudson River anaerobic meta-, para-dechlorination agent system C (J. F. Brown, R. E. Wagner, Jr., D. L. Bedard, M. J. Brennan, J. C. Carnahan, R. J. May, and J. J. Tofflemire, Northeast Environ. Sci. 3:167-179, 1984). The congener selectivity patterns indicate that a two-step process consisting of anaerobic dechlorination followed by oxidation by H850 can effectively degrade all of the congeners in Aroclor 1242 and possibly all those in Aroclor 1254.
Scanning Electron Microscope Studies of Interactions between
Agaricus bisporus
(Lang) Sing Hyphae and Bacteria in Casing Soil
Authors: Masaphy Segula , Levanon D. , Tchelet R. , Henis Y.
Published: January 2020

Relationships between the hyphae of
Agaricus bisporus
(Lang) Sing and bacteria from the mushroom bed casing layer were examined with a scanning electron microscope. Hyphae growing in the casing layer differed morphologically from compost-grown hyphae. Whereas the compost contained thin single hyphae surrounded by calcium oxalate crystals, the casing layer contained mainly wide hyphae or mycelial strands without crystals. The bacterial population in the hyphal environment consisted of several types, some attached to the hyphae with filamentlike structures. This attachment may be important in stimulation of pinhead initiation.
Elevated temperature method for recovery of Vibrio cholerae from oysters (Crassostrea gigas)
Authors: DePaola A , Kaysner C A , McPhearson R M
Published: January 2020

Of 222 Vibrio cholerae isolates from diverse clinical and environmental sources, 219 produced visible growth in alkaline peptone broth when incubated overnight at 42 degrees C. In field trials conducted to compare enrichment at incubation temperatures of 42 and 35 degrees C, significantly higher rates of isolation (P less than 0.05) and recovery (P less than 0.01) of V. cholerae from oysters were observed at 42 degrees C.
A Rapid Procedure for Purifying Pectate Lyase from
Erwinia carotovora
Based on Substrate Affinity
Authors: Ward L. , de Boer S. H.
Published: January 2020

To purify pectate lyase produced by
Erwinia carotovora
subsp.
carotovora,
we used the supernatant from 48-h-old cultures grown in broth containing sodium polypectate and yeast extract. The supernatant was combined with the enzyme substrates sodium polypectate and polygalacturonic acid, which were then precipitated with CaCl
2
. After the precipitate was washed, pectate lyase was eluted with 1.0 M NaCl.
An A-ELISA to detect hepatitis A virus in estuarine samples
Authors: Nasser A M , Metcalf T G
Published: January 2020

An amplified enzyme-linked immunosorbent assay (A-ELISA) for detecting and quantifying hepatitis A virus in estuarine water samples is described. The test was five times more sensitive than a standard ELISA and at least two times more sensitive than radioimmunoassay. Test sensitivity was unaffected by the procedures used to concentrate the virus in estuarine samples or by the presence of humic and tannic acids in test samples. Nonspecific reactions were not encountered with a number of enteroviruses or with a rotavirus. A high sensitivity and specificity combined with speed, low cost, and freedom from radiolabels made the A-ELISA useful for detecting hepatitis A virus in environmental samples. The virus was detected in 3 of 20 estuarine water samples examined by A-ELISA.
Adaptation of Yeast Cell Membranes to Ethanol
Authors: Jiménez J. , Benítez T.
Published: January 2020

A highly ethanol-tolerant
Saccharomyces
wine strain is able, after growth in the presence of ethanol, to efficiently improve the ethanol tolerance of its membrane. A less-tolerant
Saccharomyces
laboratory strain, however, is unable to adapt its membrane to ethanol. Furthermore, after growth in the presence of ethanol, the membrane of the latter strain becomes increasingly sensitive, although this is a reversible process. Reversion to a higher tolerance occurs only after the addition of an energy source and does not take place in the presence of cycloheximide.
Relationship between properties of a series of anilines and their transformation by bacteria
Authors: Paris D F , Wolfe N L
Published: January 2020

The effect of compound structure on the microbial transformation of a series of substituted anilines was investigated. For the pure-culture and environmental water samples studied, the rate of transformation of the compounds decreased in the following order: aniline greater than 3-bromoaniline greater than 3-chloroaniline greater than 3-methylaniline greater than 3-methoxyaniline greater than 3-nitroaniline greater than 3-cyanoaniline. Second-order rate constants (kb) for each compound was calculated by using bacterial and compound concentrations measured as a function of time. The rate constants correlated with steric parameters. Water samples also were used in kinetic studies with three of the compounds (aniline, 3-chloroaniline, and 3-nitroaniline) to test the relationships with mixed bacterial populations. A simple linear regression of van der Waals radius of the substituent group with log kb gave correlation coefficients (r2) of 0.924 for the river isolate and 0.99 for the mixed populations. Analyses of pure-culture and mixed-population samples by thin-layer chromatography indicate that the primary products are catechols. This finding suggests that the transformation pathway involves oxidative deamination of the anilines.
Use of Monodispersed, Fluorescently Labeled Bacteria to Estimate In Situ Protozoan Bacterivory
Authors: Sherr Barry F. , Sherr Evelyn B. , Fallon Robert D.
Published: January 2020

We have developed a procedure for preparing monodispersed, fluorescently labeled bacteria (FLB), which may be used to measure virtually instantaneous rates of protozoan bacterivory in natural waters. FLB can be prepared both from natural bacterioplankton assemblages and from clonal isolates and can be stored in frozen suspension or freeze-dried without apparent loss of fluorescence intensity. They are not toxic to protozoa and can be metabolized to support bacterivorous protozoan growth rates equal to those on the same strain of unstained, viable bacteria. In experiments comparing uptake of FLB with uptake of fluorescent latex microspheres by protozoan assemblages in a salt marsh tidal creek, we found that both pelagic oligotrichous ciliates and phagotrophic flagellates ingested FLB with a frequency 4- to 10-fold greater than they ingested the microspheres. Consequently, it appears that the use of latex microspheres leads to underestimation of protozoan bacterivory and that the FLB technique is superior for estimating instantaneous rates of in situ protozoan grazing on bacterioplankton.
Nucleotide and deduced amino acid sequences of the Staphylococcus aureus phospho-beta-galactosidase gene
Authors: Breidt F , Stewart G C
Published: January 2020

We sequenced the Staphylococcus aureus phospho-beta-galactosidase gene. The protein product of this gene consisted of 470 amino acids, giving a molecular weight of 54,557. This gene appears to be transcribed as the terminal sequence on a polycistronic message.
Survival and multiplication of Legionella pneumophila in municipal drinking water systems
Authors: States S J , Conley L F , Kuchta J M , Oleck B M , Lipovich M J , Wolford R S , Wadowsky R M , McNamara A M , Sykora J L , Keleti G
Published: January 2020

Studies were conducted to investigate the survival and multiplication of Legionella spp. in public drinking water supplies. An attempt was made, over a period of several years, to isolate legionellae from a municipal system. Sampling sites included the river water supply, treatment plant, finished water reservoir system, mains, and distribution taps. Despite the use of several isolation techniques, Legionella spp. could not be detected in any of the samples other than those collected from the river. It was hypothesized that this was due to the maintenance of a chlorine residual throughout the system. To investigate the potential for Legionella growth, additional water samples, collected from throughout the system, were dechlorinated, pasteurized, and inoculated with Legionella pneumophila. Subsequent growth indicated that many of these samples, especially those collected from areas affected by an accumulation of algal materials, exhibited a much greater ability to support Legionella multiplication than did river water prior to treatment. Chemical analyses were also performed on these samples. Correlation of chemical data and experimental growth results indicated that the chemical environment significantly affects the ability of the water to support multiplication, with turbidity, organic carbon, and certain metals being of particular importance. These studies indicate that the potential exists for Legionella growth within municipal systems and support the hypothesis that public water supplies may contaminate the plumbing systems of hospitals and other large buildings. The results also suggest that useful methods to control this contamination include adequate treatment plant filtration, maintenance of a chlorine residual throughout the treatment and distribution network, and effective covering of open reservoirs.
Cytolytic activity and immunological similarity of the Bacillus thuringiensis subsp. israelensis and Bacillus thuringiensis subsp. morrisoni isolate PG-14 toxins
Authors: Gill S S , Hornung J M , Ibarra J E , Singh G J , Federici B A
Published: January 2020

The parasporal bodies of the mosquitocidal isolates of Bacillus thuringiensis subsp. israelensis and B. thuringiensis subsp. morrisoni isolate PG-14 were compared with regard to their hemolytic and cytolytic activities and the immunological relatedness of the 28- and 65-kilodalton (kDa) proteins that occur in both subspecies. The alkali-solubilized parasporal bodies of B. thuringiensis subsp. israelensis caused 50% lysis of human erythrocytes at 1.14 micrograms/ml, whereas those of B. thuringiensis subsp. morrisoni caused similar lysis at 1.84 micrograms/ml. Preincubation of solubilized parasporal bodies with dioleolyl phosphatidylcholine significantly inhibited the hemolytic activity of both supspecies. In cytolytic assays against Aedes albopictus cells, the toxin concentrations causing 50% lysis for B. thuringiensis subsp. israelensis and B. thuringiensis subsp. morrisoni were 1.87 and 11.98 micrograms/ml, respectively. Polyclonal antibodies raised separately against the 25-kDa protein (a tryptic digest of the 28-kDa protein) or the 65-kDa protein of B. thuringiensis subsp. israelensis cross-reacted, respectively, with the 28- and the 65-kDa proteins of B. thuringiensis subsp. morrisoni. However, neither of these antibodies cross-reacted with the 135-kDa protein of either subspecies. These results indicate that the mosquitocidal and hemolytic properties of B. thuringiensis subsp. israelensis and B. thuringiensis subsp. morrisoni isolate PG-14 are probably due to the biologically related proteins that are present in the parasporal bodies of both subspecies. The lower hemolytic activity of the B. thuringiensis subsp. morrisoni may be due to the presence of lower levels of the 28-kDa protein in that subspecies.(ABSTRACT TRUNCATED AT 250 WORDS)
Denitrification in Aquifer Soil and Nearshore Marine Sediments Influenced by Groundwater Nitrate
Authors: Slater Jennifer M. , Capone Douglas G.
Published: January 2020

We estimated rates of denitrification at various depths in sediments known to be affected by submarine discharge of groundwater, and also in the parent aquifer. Surface denitrification was only measured in the autumn; at 40-cm depth, where groundwater-imported nitrate has been measured, denitrification occurred consistently throughout the year, at rates from 0.14 to 2.8 ng-atom of N g
−1
day
−1
. Denitrification consistently occurred below the zone of sulfate reduction and was sometimes comparable to it in magnitude. Denitrification occurred deep (14 to 40 cm) in the sediments along 30 km of shoreline, with highest rates occurring where groundwater input was greatest. Denitrification rates decreased with distance offshore, as does groundwater influx. Added glucose greatly stimulated denitrification at depth, but added nitrate did not. High rates of denitrification were measured in the aquifer (17 ng-atom of N g
−1
day
−1
), and added nitrate did stimulate denitrification there. The denitrification measured was enough to remove 46% of the nitrate decrease observed between 40- and 14-cm depth in the sediment.
Delignification of Wheat Straw by
Pleurotus
spp. under Mushroom-Growing Conditions
Authors: Tsang Linda J. , Reid Ian D. , Coxworth Ewen C.
Published: January 2020

Pleurotus sajor-caju, P. sapidus, P. cornucopiae
, and
P. ostreatus
mushrooms were produced on unsupplemented wheat straw. The yield of mushrooms averaged 3.6% (dry-weight basis), with an average 18% straw weight loss. Lignin losses (average, 11%) were lower than cellulose (20%) and hemicellulose (50%) losses. The cellulase digestibility of the residual straw after mushroom harvest was generally lower than that of the original straw. It does not appear feasible to simultaneously produce
Pleurotus
mushrooms and a highly delignified residue from wheat straw.
Virulent strains of Vibrio vulnificus isolated from estuaries of the United States West Coast
Authors: Kaysner C A , Abeyta C , Wekell M M , DePaola A , Stott R F , Leitch J M
Published: January 2020

Vibrio vulnificus was isolated from United States West Coast estuaries at a low frequency (5.9%) from 529 samples of water, shellfish, and sediment. Four strains tested with iron-treated mice had 50% lethal dose values ranging from 7.6 to 360 CFU, compared with a 50% lethal dose of 4.9 CFU for a clinical isolate that caused the death of a septicemic patient. The presence of this pathogen may be a hazard to users of marine beaches and consumers of raw shellfish on the West Coast, especially to persons most susceptible to V. vulnificus septicemia. Species-specific antiflagellar serum and a gene probe for cytotoxin-hemolysin production were useful for screening these environmental isolates.
Production of Pili (Fimbriae) by
Pseudomonas fluorescens
and Correlation with Attachment to Corn Roots
Authors: Vesper Stephen J.
Published: January 2020

Pseudomonas fluorescens
isolates 13525 and 2-79 were grown in Luria broth and low-nutrient medium (LNM). Pililike fibrils were very rarely produced in Luria broth but were abundantly produced in LNM. In LNM the pili were peritrichously distributed and had diameters ranging from 3 to 8 nm. Pili were purified from strain 2-79, and the pilin subunit was found to have a molecular weight of about 34,000. Strain 2-79 produced two colony types on Luria agar, nonmucoidal and mucoidal. Cells in LNM cultures of the nonmucoidal colony type were highly piliated, and cells from the mucoidal type were nearly devoid of pili. The presence of pili on nonmucoidal isolate 2-79 was quantitatively correlated with hydrophobic attachment to polystyrene, hemagglutination, and attachment to corn roots.
Microbial desulfonation of substituted naphthalenesulfonic acids and benzenesulfonic acids
Authors: Zürrer D , Cook A M , Leisinger T
Published: January 2020

Sulfur-limited batch enrichment cultures containing one of nine multisubstituted naphthalenesulfonates and an inoculum from sewage yielded several taxa of bacteria which could quantitatively utilize 19 sulfonated aromatic compounds as the sole sulfur source for growth. Growth yields were about 4 kg of protein per mol of sulfur. Specific degradation rates were about 4 to 14 mu kat/kg of protein. A Pseudomonas sp., an Arthrobacter sp., and an unidentified bacterium were examined. Each desulfonated at least 16 aromatic compounds, none of which served as a carbon source. Pseudomonas sp. strain S-313 converted 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 5-amino-1-naphthalenesulfonic acid, benzenesulfonic acid, and 3-aminobenzenesulfonic acid to 1-naphthol, 2-naphthol, 5-amino-1-naphthol, phenol, and 3-aminophenol, respectively. Experiments with 18O2 showed that the hydroxyl group was derived from molecular oxygen.
Comparison of media for recovery of total coliform bacteria from chemically treated water
Authors: Rice E W , Fox K R , Nash H D , Read E J , Smith A P
Published: January 2020

Five broth media and two solid media were compared for their ability to quantitatively recover total coliform bacteria from chemically treated water. M-Endo LES and mT7 media were used in the membrane filter technique. Lauryl tryptose broth, lactose broth, presence-absence broth, lactose broth with twice the amount of lactose, and lauryl tryptose broth with twice the amount of sodium lauryl sulfate were used in the fermentation tube procedure. The differences in recovery were not significant for the five broth media and M-Endo LES agar. The M-Endo LES and mT7 media were not significantly different; however, the five broth media did yield significantly higher counts than mT7.
Small rodents and other mammals associated with mountain meadows as reservoirs of Giardia spp. and Campylobacter spp
Authors: Pacha R E , Clark G W , Williams E A , Carter A M , Scheffelmaier J J , Debusschere P
Published: January 2020

Sixty-five percent (469 of 722) of the fecal samples collected from small rodents in the central Washington Cascade mountains were positive for Giardia spp. Trapping studies showed that microtines of the genus Microtus were heavily infected with the parasite. Morphologically the cysts and trophozoites were of the Giardia duodenalis type. Small-rodent populations appear to maintain their infection throughout the year. Our data suggest that there is no difference in the percentage of positive animals in areas receiving a lot of human use as opposed to animals in those areas receiving very little or no human use. Giardia spp. were also found in elk and beaver fecal samples. Campylobacter spp. were recovered infrequently from the small rodents inhabiting alpine meadows. Of 551 specimens cultured, less than 1% were positive for the bacterium, and the isolates were identified as Campylobacter coli. Water voles were susceptible to a human isolate of Campylobacter jejuni and shed the bacterium for several weeks. C. jejuni was also isolated from a bear fecal sample collected from a protected watershed. Our studies indicate that microtines and possibly other small rodents inhabiting mountain meadows have a potential to act as a reservoir for both Giardia spp. and Campylobacter spp. Because these animals may carry human pathogens, they should be included in animal surveys designed to assess the health risks associated with mountain watersheds.
Cloning of a
Streptococcus lactis
subsp.
lactis
Chromosomal Fragment Associated with the Ability To Grow in Milk
Authors: von Wright Atte , Tynkkynen Soile , Suominen Martin
Published: January 2020

A chromosomal fragment of 6.7 megadaltons (MDa), apparently containing the genes for milk protein utilization by
Streptococcus lactis
subsp.
lactis
SSL135, was cloned in
S. lactis
subsp.
lactis
MG1614, a proteinase-negative strain. For the cloning, the chromosomal DNA of SSL135 was cleaved with restriction enzyme
Bam
HI and the resulting fragments were ligated to the single
Bcl
I site of pVS2, a 3.3-MDa chloramphenicol-erythromycin double-resistance plasmid constructed in this laboratory.
S. lactis
subsp.
lactis
MG1614 was transformed by using this ligation mixture and selecting for chloramphenicol resistance and growth in citrated milk medium. One clone containing a 10.0-MDa plasmid, subsequently designated as pVS6, was chosen for further studies. Despite the lack of homology with previously characterized proteinase genes of lactic streptococci, the cloned insert consistently conveyed the ability to grow in milk to proteinase-negative recipients in repeated transformation experiments. The genetic evidence suggests that the main part of the gene(s) for the proposed proteinase activity is located within a 3.8-MDa
Bgl
II fragment of the clone.
Isozyme Variation among 40
Frankia
Strains
Authors: Gardes Monique , Bousquet Jean , Lalonde Maurice
Published: January 2020

Forty
Frankia
strains belonging to the
Alnus
and
Elaeagnus
host specificity groups and isolated from various plant species from different geographical areas were characterized by the electrophoretic separation of isozymes of eight enzymes. All the enzyme systems that were investigated showed large variation. Diaphorases and esterases gave multiple band patterns and confirmed the identification of specific
Frankia
strains. Less variability was observed with enzymes such as phosphoglucose isomerase, leucine aminopeptidase, and malate dehydrogenase, which allowed for the delineation of larger groups of
Frankia
strains. Cluster analysis, based on the pair-wise similarity coefficients calculated between strains, delineated three large, dissimilar groups of
Frankia
strains, although each of these groups contained a large amount of heterogeneity. However, numerous
Frankia
strains, mainly from the
Alnus
host specificity group, demonstrated a perfect homology for all the enzymes tested.
Thermostable Amylolytic Enzymes from a New
Clostridium
Isolate
Authors: Madi E. , Antranikian G. , Ohmiya K. , Gottschalk G.
Published: January 2020

A new
Clostridium
strain was isolated on starch at 60°C. Starch, pullulan, maltotriose, and maltose induced the synthesis of α-amylase and pullulanase, while glucose, ribose, fructose, and lactose did not. The formation of the amylolytic enzymes was dependent on growth and occurred predominantly in the exponential phase. The enzymes were largely cell bound during growth of the organism with 0.5% starch, but an increase of the starch concentration in the growth medium was accompanied by the excretion of α-amylase and pullulanase into the culture broth; but also by a decrease of total activity. α-Amylase, pullulanase, and α-glucosidase were active in a broad temperature range (40 to 85°C) and displayed temperature optima for activity at 60 to 70°C. During incubation with starch under aerobic conditions at 75°C for 2 h, the activity of both enzymes decreased to only 90 or 80%. The apparent

K
m

values of α-amylase, pullulanase, and α-glucosidase for their corresponding substrates, starch, pullulan, and maltose were 0.35 mg/ml, 0.63 mg/ml, and 25 mM, respectively.
A rapid test for chitinase activity that uses 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminide
Authors: O'Brien M , Colwell R R
Published: January 2020

A total of 101 strains of bacteria from environmental and clinical sources, most of which were gram negative, were tested for chitobiase activity by using a filter paper spot test with 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminide as the substrate. The results were compared with those obtained by a conventional plate method for chitinase activity by using colloidal chitin as the substrate. There was excellent agreement in the results for both methods. The filter paper spot test with 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminide has the advantages of being rapid, simple to perform, and inexpensive. This method should be adaptable to a wider range of microorganisms, particularly those with unusual growth requirements.
Methods To Alter the Recovery and Nodule Location of
Bradyrhizobium japonicum
Inoculant Strains on Field-Grown Soybeans
Authors: Kamicker Barbara J. , Brill Winston J.
Published: January 2020

Three strains of
Bradyrhizobium japonicum,
I17, 110, and 61A76, were evaluated for their ability to form nodules on field-grown soybeans in soil with a highly competitive indigenous
B. japonicum
population. The predominant indigenous strain, 0336, in the field site used was unlike the more common isolates from Midwestern soils which belong to the 123 or 138 serogroups. This strain persisted in the soil for at least 30 years without any soybean crops. The three inoculant strains differed in their ability to compete with indigenous strains for nodule formation. Four different inoculation treatments were tested in three adjacent fields. When the amount of inoculum was increased, a higher proportion of nodules contained the inoculant strain. The most competitive inoculant strain was I17, a recent field isolate. Strain 61A76 was better than 110. There was no difference in recovery of the inoculant strains on the Hodgson or Corsoy soybean cultivars, nor was there a difference in recovery of the inoculant strains during the growing season. The vertical distribution of nodules containing the inoculant strains was affected by the method of adding the inoculant to the soil. Inoculant added to the seed furrow produced nodules mainly in the top region of the soybean root. Inoculant tilled into the soil produced nodules primarily in the bottom part of the root. The nodules that were produced in the bottom part of the root are younger and may contribute significant amounts of fixed nitrogen to the soybean during seed formation.
High-Efficiency Conversion of Pyruvate to Acetoin by
Lactobacillus plantarum
during pH-Controlled and Fed-Batch Fermentations
Authors: Montville Thomas J. , Hsu Amy Han-Ming , Meyer Mary E.
Published: January 2020

The influence of pH on the type and concentration of metabolites produced from pyruvate by
Lactobacillus plantarum
ATCC 8014 was examined in pH-controlled fermentors at pH values of 4.5 to 6.5. Specific growth rates, cell dry weights, and diacetyl concentrations were highest at pH 5.5, with values of 0.78 h
−1
, 190 mg/liter, and 1.2 mM, respectively. While the conversion efficiency (millimoles of acetoin formed per millimoles of pyruvate utilized) was highest (94.6%) at pH 4.5, acetoin levels were similar (20 mM) between pH 4.5 and 5.5. Feeding stationary-phase cells exogenous pyruvate increased acetoin levels to 78 mM.
Phototaxis in the Marine Fungus
Rhizophydium littoreum
Authors: Muehlstein Lisa K. , Amon James P. , Leffler Deborah L.
Published: January 2020

Phototaxis appears to be a factor that influences the dispersal of zoospores of the marine fungus
Rhizophydium littoreum.
By using a quantitative method to study phototaxis, zoospores were found to be positively phototactic toward blue wavelengths of light. White light in the range of 20 to 6,000 microeinsteins m
−2
s
−1
and blue light in the range of 1 to 300 microeinsteins m
−2
s
−1
gave positive responses in the laboratory. Results of field studies confirmed the ability of zoospores to respond to light under natural conditions. Phototaxis may be an important adaptive mechanism which influences vertical migration of zoospores in the photic zone where plant products are available as nutrients.
Correlation of in vitro challenge testing with consumer use testing for cosmetic products
Authors: Brannan D K , Dille J C , Kaufman D J
Published: January 2020

An in vitro microbial challenge test has been developed to predict the likelihood of consumer contamination of cosmetic products. The challenge test involved inoculating product at four concentrations (30, 50, 70, and 100%) with microorganisms known to contaminate cosmetics. Elimination of these microorganisms at each concentration was followed over a 28-day period. The test was used to classify products as poorly preserved, marginally preserved, or well preserved. Consumer use testing was then used to determine whether the test predicted the risk of actual consumer contamination. Products classified by the challenge test as poorly preserved returned 46 to 90% contaminated after use. Products classified by the challenge test as well preserved returned with no contamination. Marginally preserved products returned with 0 to 21% of the used units contaminated. As a result, the challenge test described can be accurately used to predict the risk of consumer contamination of cosmetic products.