bluuebunny/crossref_metadata_2025 huggingface dataset:
Mating System and Basidiospore Formation in the Lignin-Degrading Basidiomycete
Phanerochaete chrysosporium
Authors: Alic Margaret , Letzring Celia , Gold Michael H.
Published: January 2020

Prototrophic strains recovered from crosses between auxotrophic strains of the lignin-degrading basidiomycete
Phanerochaete chrysosporium
were induced to fruit. The progeny of most of these self-crosses were prototrophic, indicating that the nuclei of the original prototroph were wild-type recombinants rather than complementary heterokaryons and that the binucleate basidiospores of this organism are homokaryotic. Various wild-type strains were shown to have multinucleate cells lacking clamp connections and to possess a variable number of sterigmata per basidium. Colonies arising from single conidia of various wild-type strains were all capable of producing fruit bodies and basidiospores. In addition, single basidiospores from three wild-type strains all produced fruit bodies and basidiospores. Nonfruiting as well as fruiting isolates were obtained from single basidiospores of five other wild-type strains. Basidiospores from these fruiting isolates always yielded colonies that fruited, again indicating that the spores are homokaryotic. Nonfruiting isolates from the same strain did not produce basidiospores when allowed to form a heterokaryon, implying that these isolates do not represent mating types. All this evidence indicates that
P. chrysosporium
has a primary homothallic mating system. In addition to fruiting and nonfruiting phenotypes, basidiospores from strain OGC101, a derivative of ME-446, gave rise to colonies which did not grow on cellulose (Cel
−
). The fruiting, nonfruiting, and Cel
−
phenotypes differed from each other and from the parental wild-type strain in a variety of characteristics, including growth, conidiation, and evolution of
14
CO
2
from
14
C-side chain-labeled lignin, indicating that strain OCG101 is a heterokaryon.
Effect of adaptation to phenol on biodegradation of monosubstituted phenols by aquatic microbial communities
Authors: Shimp R J , Pfaender F K
Published: January 2020

The adaptation of a mixed aquatic microbial community to phenol was examined in microcosms receiving phenol as a sole carbon source. Extended exposure (adaptation) to phenol resulted in adaptation of the microbial community to the structurally related aromatic compounds m-cresol, m-aminophenol, and p-chlorophenol. The increased biodegradation potential of the phenol-adapted microbial community was accompanied by a concurrent increase in the number of microorganisms able to degrade the three test compounds. Thus, adaptation to the three test chemicals was likely a growth-related result of extended exposure to phenol. The results indicate that adaptation to a single chemical may increase the assimilative capacity of an aquatic environment for other related chemicals even in the absence of adaptation-inducing levels of those materials.
Industrial Application of Artificially Induced Diploid Strains of
Torulaspora delbrueckii
Authors: Ohshima Yoshinobu , Sugaura Toshio , Horita Munehiro , Sasaki Takashi
Published: January 2020

Diploid strains of
Torulaspora delbrueckii
were tested for industrial application. Because the cell volume of the diploid strain was three times as large as that of the parental haploid strain, collection and subsequent dehydration to make compressed yeast cakes were greatly improved with the diploid YL3. The time required for dehydration of the diploid strain was shortened to 1/2.5 that of the parent strain under conventional conditions. Moreover, for the diploid cells frequent filter changes for dehydration were not required, which was the case with parental cells. Fermentation activity and tolerance to freeze-thawing in dough were succesfully inherited by the diploid strains. The diploid YL3 showed nearly the same activity as the diploid F31 in bread making. However, the endurance period of yeast cakes when stored at 30°C without softening to lead to liquefaction was much longer in YL3 (199 h) than in F31 (132 h). This superiority was ascribed to the fact that YL3 was induced through direct diploidization and had no genetic defect on chromosomes because the wild-type strain was employed as the parent, whereas F31 was obtained through protoplast fusion from two auxotrophic mutants and carried at least two mutagenized genes that were masked by heterolallelism.
Rapid Assay for Microbially Reducible Ferric Iron in Aquatic Sediments
Authors: Lovley Derek R. , Phillips Elizabeth J. P.
Published: January 2020

The availability of ferric iron for microbial reduction as directly determined by the activity of iron-reducing organisms was compared with its availability as determined by a newly developed chemical assay for microbially reducible iron. The chemical assay was based on the reduction of poorly crystalline ferric iron by hydroxylamine under acidic conditions. There was a strong correlation between the extent to which hydroxylamine could reduce various synthetic ferric iron forms and the susceptibility of the iron to microbial reduction in an enrichment culture of iron-reducing organisms. When sediments that contained hydroxylamine-reducible ferric iron were incubated under anaerobic conditions, ferrous iron accumulated as the concentration of hydroxylamine-reducible ferric iron declined over time. Ferrous iron production stopped as soon as the hydroxylamine-reducible ferric iron was depleted. In anaerobic incubations of reduced sediments that did not contain hydroxylamine-reducible ferric iron, there was no microbial iron reduction, even though the sediments contained high concentrations of oxalate-extractable ferric iron. A correspondence between the presence of hydroxylamine-reducible ferric iron and the extent of ferric iron reduction in anaerobic incubations was observed in sediments from an aquifer and in fresh- and brackish-water sediments from the Potomac River estuary. The assay is a significant improvement over previously described procedures for the determination of hydroxylamine-reducible ferric iron because it provides a correction for the high concentrations of solid ferrous iron which may also be extracted from sediments with acid. This is a rapid, simple technique to determine whether ferric iron is available for microbial reduction.
Identification of dimethyl disulfide-forming bacteria isolated from activated sludge
Authors: Tomita B , Inoue H , Chaya K , Nakamura A , Hamamura N , Ueno K , Watanabe K , Ose Y
Published: January 2020

Twenty-four strains with high dimethyl disulfide (DMDS)-forming ability were isolated from activated sludge and identified to the genus level. These bacteria were classified into four groups (A, B, C, and D) by the API ZYM System (API System S.A., Montalieu, France). Group A (three strains) was identified as genus Lactobacillus by the API 20B System, by the method of Cowan and Steel, and by production of lactic acid as confirmed by gas-liquid chromatography. Group B (eight strains) was identified as genus Corynebacterium by API 20B and the Cowan and Steel method. Group C (one strain) was suggested to belong to genus Corynebacterium by the API 20B System. Group D (12 strains) was identified as genus Pseudomonas or Alcaligenes by the API 20B System, as genus Alcaligenes by the Cowan and Steel method, and as Achromobacter group Vd by the API 20NE System. However, on the basis of guanine-plus-cytosine contents in DNA and form of flagella, these strains were identified as genus Pseudomonas. Formation of DMDS from DL-methionine and S-methyl-L-cysteine was tested. DMDS-forming bacteria isolated from activated sludge formed DMDS from both precursors. In genus Pseudomonas, P. aeruginosa could not form DMDS from either precursor, but P. acidovorans, P. alcaligenes, P. pseudoalcaligenes, and P. testosteroni formed DMDS. In genus Alcaligenes, A. denitrificans subsp. xylosoxydans, A. denitrificans subsp. denitrificans, A. faecalis, and A. odorans formed DMDS from both precursors. Achromobacter group Vd formed DMDS from S-methyl-L-cysteine, but could not from DL-methionine.
Use of sodium dodecyl sulfate-polymyxin B-sucrose medium for isolation of Vibrio vulnificus from shellfish
Authors: Bryant R G , Jarvis J , Janda J M
Published: January 2020

The differential and selective sodium dodecyl sulfate-polymyxin B-sucrose medium (SPS) of Kitaura et al. (T. Kitaura, S. Doke, I. Azuma, M. Imaida, K. Miyano, K. Harada, and E. Yabuuchii, FEMS Microbiol. Lett. 17:205-209, 1983), which highlights alkylsulfatase activity, was evaluated for its potential use in the direct isolation and enumeration of Vibrio vulnificus from shellfish. V. vulnificus was detected by this method in six of nine shellfish samples collected from diverse geographic locales during the summer of 1986. Direct enumeration of V. vulnificus at 7.0 X 10(2) to 2.2 X 10(4) CFU/g of shellfish was achieved on SPS agar. All sample results were confirmed in parallel examinations by using conventional glucose-salt-Teepol (Shell Oil Co.) broth and alkaline peptone water enrichment with plating onto thiosulfate-citrate-bile salts-sucrose agar. Additionally, alkylsulfatase activity was evaluated in vitro for 97 strains representing 14 Vibrio spp. V. vulnificus and Vibrio cholerae-01 were the only species consistently found to possess this activity. The range of plating efficiencies for random V. vulnificus strains analyzed on SPS was 11 to 74% (mean, 39%). The use of SPS shows great promise for the study of shellfish and other environmental sources for V. vulnificus.
Split-Root Assays Using
Trifolium subterraneum
Show that
Rhizobium
Infection Induces a Systemic Response That Can Inhibit Nodulation of Another Invasive
Rhizobium
Strain
Authors: Sargent Lucy , Huang Shizhen Z. , Rolfe Barry G. , Djordjevic Michael A.
Published: January 2020

Subterranean clover plants possessing two equally infectible and robust lateral root systems (“split roots”) were used in conjunction with several specific mutant strains (derived from
Rhizobium trifolii
ANU843) to investigate a systemic plant response induced by infective
Rhizobium
strains. This plant response controls and inhibits subsequent nodulation on the plant. When strain ANU843 was inoculated onto both root systems simultaneously or 24, 48, 72, or 96 h apart, an inhibitory response occurred which retarded nodulation on the root exposed to the delayed inoculum but only when the delay period between inocula was greater than 24 h. Equal numbers of nodules were generated on both roots when ANU843 was inoculated simultaneously or 24 h apart. The ability to infect subterranean clover plants was required to initiate the plant inhibitory response since preexposure of one root system to non-nodulating strains did not retard the ability of the wild-type strain to nodulate the opposing root system (even when the delay period was 96 h). Moreover, the use of specific Tn
5
-induced mutants subtly impaired in their ability to nodulate demonstrated that the plant could effectively and rapidly discriminate between infections initiated by either the parent or the mutant strains. When inoculated alone onto clover plants, these mutant strains were able to infect the most susceptible plant cells at the time of inoculation and induce nitrogen-fixing nodules. However, the separate but simultaneous inoculation on opposing root systems of the parent and the mutant strains resulted in the almost complete inhibition of the nodulation ability of the mutant strains. We concluded that the mutants were affected in their competitive ability, and this finding was reflected by poor nodule occupancy when the mutants were coinoculated with the parent strain onto a single root system. Thus the split-root system may form the basis of a simple screening method for the ranking of competitiveness of various rhizobia on small seeded legumes.
Effect of high-fiber and high-oil diets on the fecal flora of swine
Authors: Moore W E , Moore L V , Cato E P , Wilkins T D , Kornegay E T
Published: January 2020

Six pairs of pigs were fed a basal diet, a high-fiber diet, and a diet high in corn oil in different sequences to minimize the carry-over effect of diet. After 2 months on each diet, a fecal specimen from each pig was cultured on nonselective medium in roll tubes. Fifty colonies were randomly selected from each fecal sample, and isolates were characterized to identify a representative cross section of the fecal flora. The bacterial composition of the fecal flora differed between basal and high-fiber diets (P = 0.002) and between high-fiber and high-oil diets (P = 0.015). However, the floras were not significantly different between the basal and the high-oil diets (P = 0.135), nor were the floras of the 12 individual pigs (each on all three diets) statistically different (P = 0.103). Only 14 of the 160 observed taxa have been detected in the human fecal flora, and only 159 of 1,871 total isolates (8.5%) were members of described species. The most common isolate was a Streptococcus species similar to that reported by Robinson et al. (I. M. Robinson, S. C. Whipp, J. A. Bucklin, and M. J. Allison, Appl. Environ. Microbiol. 48:964-969, 1984), which was found in 34 of 36 samples and which represented 27.5% of all isolates. Lactobacillus, Fusobacterium, Eubacterium, Bacteroides, and Peptostreptococcus species were the next most common bacteria. Escherichia coli represented 1.7% of all fecal isolates, which is somewhat higher than the 0.1 to 0.6% observed in human feces cultured similarly with prereduced anaerobically sterilized media.(ABSTRACT TRUNCATED AT 250 WORDS)
Sulfur Reduction by the Extremely Thermophilic Archaebacterium
Pyrodictium occultum
Authors: Parameswaran A. K. , Provan C. N. , Sturm F. J. , Kelly R. M.
Published: January 2020

The relationship between growth and biological sulfur reduction for the extremely thermophilic archaebacterium
Pyrodictium occultum
was studied over a temperature range of 98 to 105°C. The addition of yeast extract (0.2 g/liter) to the medium was found to increase hydrogen sulfide production significantly, especially at higher temperatures. Sulfide production in uninoculated controls with and without yeast extract was noticeable but substantially below the levels observed in samples containing the microorganism.
Degradation of the framework of the Chlamydomonas cell wall by proteases present in a commercially available alpha-amylase preparation
Authors: Imam S H , Snell W J
Published: January 2020

A commercially available alpha-amylase derived from Bacillus licheniformis contained an enzymatic activity able to degrade the inner portion or framework of the cell wall of Chlamydomonas reinhardtii. Both the wall-degrading activity and the contaminating protease were destroyed by heating the alpha-amylase preparation at 90 degrees C for 30 min. Since the alpha-amylase activity was uneffected by heat treatment, we conclude that it was not the alpha-amylase but the contaminating protease in the preparation that was responsible for the cell wall-degrading activity.
Appearance of enzyme activities catalyzing conversion of sterigmatocystin to aflatoxin B1 in late-growth-phase Aspergillus parasiticus cultures
Authors: Cleveland T E , Lax A R , Lee L S , Bhatnagar D
Published: January 2020

Two activities involved in terminal pathway conversion of sterigmatocystin to aflatoxin B1 were isolated from an aflatoxin-nonproducing mutant of Aspergillus parasiticus (avn-1), and the time course of appearance of the activities in culture was determined. Subcellular fractionation of fungal mycelia resolved the two activities into a postmicrosomal activity which catalyzed conversion of sterigmatocystin to O-methylsterigmatocystin and a microsomal activity which converted O-methylsterigmatocystin to aflatoxin B1. The two activities were absent in 24-h-old cells, increased to optimum levels during the stationary phase, and then declined.
Clinical hypersensitivity to specific aerosol challenge in parenterally immunized calves
Authors: Taylor F G , Jones C D , Bourne J
Published: January 2020

This paper reports an experiment designed to demonstrate that the calf lung can be sensitized to a specific respirable challenge following parenteral immunization with a nonliving antigen (human serum albumin). The possibility that immune-mediated injury could subsequently interfere with nonspecific mucosal defenses was also investigated by infecting calves with Pasteurella haemolytica after the antigen challenge and assessing pulmonary clearance of the organism. The results indicated that specific aerosol challenge produces reversible signs of respiratory hypersensitivity and that persistence of incidental infection in the upper respiratory tract is potentiated. Since the calves were sensitized by an immunization regime which imitated conventional vaccination, this study highlights the potential dangers of inactivated parenteral respiratory vaccines.
A method for genetic transformation of nonprotoplasted Streptococcus lactis
Authors: Sanders M E , Nicholson M A
Published: January 2020

Plasmid transformation of whole cells of Streptococcus lactis LM0230 was demonstrated. The procedure required polyethylene glycol and incubation in hypertonic media, but did not require enzymatic cell wall digestion. Conditions were optimized, yielding 5 X 10(5) transformants per micrograms of pSA3 DNA. Variables tested for effect on transformation efficiency included molecular weight, concentration, and pH of polyethylene glycol; cell density; plating media; DNA concentration; heat shock; and incubation of cells in hypertonic buffer. DNAs transformed included pSA3, pVA856, pTV1, and c2 phi. Transformation from DNA-DNA ligation mixes, with DNA not purified through density gradients, and with previously frozen cells was also achieved. The method described here for transformation of nonprotoplasted cells of LM0230 is unique, and to date has not been applied successfully to other lactic acid bacteria.
Distribution of indicator bacteria and Vibrio parahaemolyticus in sewage-polluted intertidal sediments
Authors: Shiaris M P , Rex A C , Pettibone G W , Keay K , McManus P , Rex M A , Ebersole J , Gallagher E
Published: January 2020

The impact of a sewage point source on the bacterial densities in an intertidal mud flat in Boston Harbor, Mass., was investigated. The area, Savin Hill Cove, acts as a receiving basin for a combined storm and sewage outlet (CSO). Preliminary examination of sediments and overlying water at high tide demonstrated that fecal coliforms were present in sediments at abundances 2 to 4 orders of magnitude higher than in the overlying water column. The following bacterial counts were determined from sediments along a sampling transect extending 460 m from the CSO: total bacteria by epifluorescent microscopy, heterotrophic bacteria by plate counts on nutrient-rich and nutrient-poor media, fecal coliforms and enterococci by membrane filtration, and Vibrio parahaemolyticus by a most-probable-number technique with a resuscitation step. Median sediment grain size, average tidal exposure, carbon/nitrogen ratio, and total organic carbon were also measured. All bacterial indices, except for V. parahaemolyticus, declined significantly with distance from the outfall. Multiple regression analysis indicated that tidal exposure (low tides) may affect densities of total bacteria. Fecal coliforms and enterococci were still present in appreciable numbers in sediments as far as 460 m away from the CSO. In contrast, V. parahaemolyticus densities did not correlate with the other bacterial counts nor with any of the environmental parameters examined. These results indicate that intertidal sediments which adjoin point sources of pollution are severely contaminated and should be considered as potentially hazardous reservoirs of sewage-borne diseases.
An alkaline approach to treating cooling towers for control of Legionella pneumophila
Authors: States S J , Conley L F , Towner S G , Wolford R S , Stephenson T E , McNamara A M , Wadowsky R M , Yee R B
Published: January 2020

Earlier field and laboratory studies have shown that Legionella species survive and multiply in the pH range 5.5 to 9.2. Additionally, the technical feasibility of operating cooling towers at elevated alkalinities and pH has previously been documented by published guidelines. The guidelines indicate that these conditions facilitate corrosion control and favor chlorine persistence which enhances the effectiveness of continuous chlorination in biofouling control. This information suggests that control of Legionella species in cooling towers can be accomplished by operating the towers under alkaline conditions. To test this possibility, we collected water samples over a period of months from a hospital cooling tower. The samples were analyzed for a variety of chemical parameters. Subsamples were pasteurized and inoculated with non-agar-passaged Legionella pneumophila which had been maintained in tap water. Correlation of subsequent Legionella growth with corresponding pH and alkalinity values revealed statistically significant inverse associations. These data support the hypothesis that operating cooling towers outside of the optimal conditions for Legionella growth (e.g., at elevated alkalinities and a pH greater than 9) may be a useful approach to controlling growth in this habitat.
Microbial transformation of precocene II: oxidative reactions by Streptomyces griseus
Authors: Sariaslani F S , McGee L R , Ovenall D W
Published: January 2020

Various species of "Streptomyces," "Aspergillus," "Rhodotorula," "Brevilegnia," "Syncephalastrum," and "Stysanus" were found to transform precocene II to three major metabolites. These major biotransformation products were isolated from a preparative-scale incubation of precocene II with Streptomyces griseus and were conclusively identified as (-)cis- and (+)trans-precocene II-3,4-dihydrodiols and (+)-3-chromenol. 18O2 incorporation studies indicated the involvement of a monooxygenase enzyme system in precocene II transformation by S. griseus. A mechanism is proposed for the formation of (+)-3-chromenol.
Infectivity and antigenicity reduction rates of human rotavirus strain Wa in fresh waters
Authors: Pancorbo O C , Evanshen B G , Campbell W F , Lambert S , Curtis S K , Woolley T W
Published: January 2020

The rates of inactivation of human rotavirus type 2 (strain Wa) (HRV-Wa) and poliovirus type 1 (strain CHAT) were compared in polluted waters (creek water and secondary effluent before chlorination) and nonpolluted waters (lake water, groundwater, and chlorinated tap water). Viral infectivity titers were determined by plaque assays, while HRV-Wa antigenicity also was monitored by an enzyme-linked immunosorbent assay. Both viruses persisted longest in lake water and shortest in tap water. The actual inactivation times (i.e., times required for two-log10 reductions of initial viral titers) for the two viruses were significantly different in all waters except tap water. With the exception of the groundwater and secondary effluent results, the HRV-Wa inactivation times in the fresh waters tested were significantly different. Owing perhaps to aggregation, HRV-Wa appeared less susceptible to the effects of chlorine than previously reported for this virus and for the simian rotavirus SA11. HRV-Wa displayed prolonged survival in lake water and groundwater exceeding that previously reported for the SA11 virus. The HRV-Wa infectivity reduction rate (ki) was significantly correlated with the water pH (i.e., as pH increased, ki increased). The water pH may have influenced viral aggregation and thereby HRV-Wa susceptibility to other virucidal factors in the water. Enzyme-linked immunosorbent assay results showed similar inactivation patterns with the most significant reduction in HRV-Wa antigenicity occurring in polluted waters and tap water. In all waters, particularly tap water, infectivity declined at a faster rate than antigenicity. It is proposed that HRV-Wa can be used as a model for future studies of rotaviral persistence in the aquatic environment.
Incorporation of Exogenous Purines and Pyrimidines by
Methanococcus voltae
and Isolation of Analog-Resistant Mutants
Authors: Bowen Timothy L. , Whitman William B.
Published: January 2020

Methanococcus voltae
incorporated exogenous adenine, guanine, hypoxanthine, and uracil, but not thymine. Growth of
M. voltae
was also sensitive to purine and pyrimidine analogs. Of the 20 analogs tested, 12 were inhibitory at 1 mg/ml. The most effective inhibitors were purine analogs with endocyclic substitutions. Nucleoside analogs and analogs with exocyclic substitutions or additions were less effective. Four purine analogs, 8-aza-2,6-diaminopurine, 8-azaguanine, 8-azahypoxanthine, and 6-mercaptopurine and one pyrimidine analog, 6-azauracil, were especially toxic. The MICs were 20, 0.5, 2.0, 80, and 10 μg/ml, respectively. Spontaneous resistance mutants were isolated for these five analogs. The MICs for these mutants were 20.5, 8.2, >65, >41, and 20.5 mg/ml, respectively. These concentrations far exceeded the solubilities of the analogs and represented an increase in resistance of at least three orders of magnitude. In addition to demonstrating cross resistance to several of the analogs, four of these mutants lost the ability to incorporate exogenous bases. These appeared to be mutations in the salvage pathways for purines and pyrimidines. In contrast, the mutant resistant to 6-mercaptopurine was not defective in purine uptake. Instead, it degraded 6-mercaptopurine. In the presence or absence of high concentrations of the analogs, the growth rates of the resistant mutants were no less than one-half of the growth rate of the wild type in the absence of the analog. The high level of resistance and rapid growth are very desirable properties for the application of the mutants in genetic experiments.
Isolation and characterization of mutants blocked in T-2 toxin biosynthesis
Authors: Beremand M N
Published: January 2020

Mutants of Fusarium sporotrichioides NRRL 3299 that were blocked or altered in the biosynthesis of the trichothecene T-2 toxin were generated by UV treatment and identified by a rapid screen in which monoclonal antibodies to T-2 were used. Three stable mutants were isolated and chemically characterized. Two mutants accumulated diacetoxyscirpenol, which suggests that they were defective in the step required for the addition of a hydroxyl group to the C-8 position in the trichothecene core structure. The third mutant appeared to be partially blocked at an early step or regulatory point in the pathway. This represents the first isolation of mutants in a trichothecene biosynthetic pathway.
Chemically Defined Medium for the Accumulation of Intracellular Malate Dehydrogenase by
Streptomyces aureofaciens
Authors: Laluce Cecília , Ernandes José Roberto , Molinari Rubens
Published: January 2020

A chemically defined medium was developed for the production of intracellular malate dehydrogenases by
Streptomyces aureofaciens
NRRL-B 1286. The composition of the medium (per liter) was as follows: 50 g of starch, 4 g of ammonium sulfate, 7.32 g of
l
-aspartic acid, 13.8 g of MgSO
4
· 7H
2
O, 1.7 g of K
2
HPO
4
, 0.01 g of ZnSO
4
· 7H
2
O, 0.01 g of FeSO
4
· 7H
2
O, 0.01 g of MnSO
4
· H
2
O, and 0.005 g of CoSO
4
· 7H
2
O. The pH of the medium was adjusted to 6.7 to 7.0 after sterilization. The activity of the intracellular malate dehydrogenases of the crude cell extract was greatest after 40 h of mycelium growth in a rotary shaker at 30°C. The best temperature for the enzyme reactions was approximately 35°C for NAD
+
activity at pH 9.7 and 40°C for NADP
+
-linked enzyme at pH 9.0. The NAD
+
activity required Mg
2+
, and both activities were sensitive to SH-group reagents. The NADP
+
-dependent activity remained completely stable, and the NAD
+
-dependent activity decreased to a very low residual level after 30 min at 60°C.
Role of Chemotaxis in Solvent Production by
Clostridium acetobutylicum
Authors: Gutierrez Noemi A. , Maddox Ian S.
Published: January 2020

The motility of
Clostridium acetobutylicum
has been investigated during a typical batch fermentation process for solvent production. The motility is characterized by “runs” during the early phase of sugar utilization and acid production, but this changes to “tumbles” during the onset of solventogenesis. Sugars and undissociated acetic and butyric acids have been shown to be attractants for the bacterium, while acetone, butanol, ethanol, and dissociated acetate and butyrate are repellents. It is suggested that chemotactic responses explain why highly motile cells are strongly solventogenic.
Demonstration of mucosa-associated microbial populations in the colons of mice
Authors: Tannock G W
Published: January 2020

Gram-stained sections prepared in a microtome-cryostat and examined by light microscopy confirmed the observation with scanning electron microscopy made by other workers that microbes inhabit a zone adjacent to the mucosal surface of the proximal colon of mice. Microbes in the midcolon, in contrast, are restricted to the fecal pellets occupying the intestinal lumen.
Inadequacy of the Eucaryote Inhibitor Cycloheximide in Studies of Protozoan Grazing on Bacteria at the Freshwater-Sediment Interface
Authors: Tremaine Sarah C. , Mills Aaron L.
Published: January 2020

Four guilds from a lake sediment-water interface microbial community were isolated and tested for sensitivity to cycloheximide (0.1 to 200 mg liter
−1
). Field experiments were conducted to compare the inhibition, dilution, and filtration methods for determining grazing rates. Cycloheximide inhibited anaerobic bacteria at 50 mg liter
−1
, and inhibition of bacterial growth was observed in the grazing experiments. The results show that the assumption of selective inhibition of heterotrophic eucaryotes was violated and preclude the use of cycloheximide in grazing experiments.
Mixed fungal populations and lignocellulosic tissue degradation in the bovine rumen
Authors: Akin D E , Rigsby L L
Published: January 2020

Anaerobic fungi in ruminal fluid from cows eating Bermuda grass hay plus a grain and minerals supplement were evaluated for diversity in sporangial morphotypes and colony growth patterns and for the degradation of various lignocelluloses. In selective cultures containing streptomycin and penicillin, an active population of ruminal fungi colonized leaf blades and degraded fiber at rates and extents almost equal to that of the total ruminal population. Three major sporangial morphotypes were consistently observed on leaf blades: oval, globose, and fusiform. Fungal colonies representing three distinct growth types consistently developed in anaerobic roll tubes inoculated with strained ruminal fluid. Sporangial morphotypes could not be matched to colony types due to multiple sporangial forms within a colony. Under identical growth conditions, one type exhibited a monocentric growth pattern, while two types exhibited polycentric growth patterns previously unreported in ruminal fungi. Mixed ruminal fungi in selective cultures or in digesta taken directly from the rumen produced a massive clearing of the sclerenchyma. Quantitation of tissue areas in cross sections by light microscopic techniques showed that fungal incubations resulted in significant (P = 0.05) increases in sclerenchyma degradation compared to whole ruminal fluid incubations. The mestome cell wall was at times penetrated and partially degraded by fungi; the colonization was less frequent and to a lesser degree than with the sclerenchyma. Conversely, ruminal bacteria were not observed to degrade the mestome sheath. Phenolic monomers at 1 mM concentrations did not stimulate to a significant (P = 0.05) extent the dry weight loss or fungal colonization of leaf blades; at 10 mM concentrations cinnamic and benzoic acids were toxic to ruminal fungi.
Enzymatic methylation of sulfide, selenide, and organic thiols by Tetrahymena thermophila
Authors: Drotar A , Fall L R , Mishalanie E A , Tavernier J E , Fall R
Published: January 2020

Cell extracts from the ciliate Tetrahymena thermophila catalyzed the S-adenosylmethionine-dependent methylation of sulfide. The product of the reaction, methanethiol, was detected by a radiometric assay and by a gas-chromatographic assay coupled to a sulfur-selective chemiluminescence detector. Extracts also catalyzed the methylation of selenide, and the product was shown by gas chromatography-mass spectrometry to be methaneselenol. The sulfide and selenide methyltransferase activities copurified with the aromatic thiol methyltransferase previously characterized from this organism (A.-M. Drotar and R. Fall, Pestic. Biochem. Physiol. 25:396-406, 1986), but heat inactivation experiments suggested the involvement of distinct sulfide and selenide methyltransferases. Short-term toxicity tests were carried out for sulfide, selenide, and their methylated derivatives; the monomethylated forms were somewhat more toxic than the nonmethylated or dimethylated compounds. Cell suspensions of T. thermophila exposed to sulfide, methanethiol, or their selenium analogs emitted methylated derivatives into the headspace. These results suggest that this freshwater protozoan is capable of the stepwise methylation of sulfide and selenide, leading to the release of volatile methylated sulfur or selenium gases.
Membrane ATPases and acid tolerance of Actinomyces viscosus and Lactobacillus casei
Authors: Bender G R , Marquis R E
Published: January 2020

Lactobacillus casei ATCC 4646 and Actinomyces viscosus OMZ105E were found to differ markedly in acid tolerance. For example, pH profiles for glycolysis of intact cells in dense suspensions indicated that glycolysis by L. casei had an optimal pH of about 6.0 and that glucose degradation was reduced by 50% at a pH of 4.2. Comparable values for A. viscosus cells were at pHs of about 7.0 and 5.6. The difference in acid tolerance appeared to depend mainly on membrane physiology, and the addition of 40 microM gramicidin to cell suspensions increased the sensitivity of the glycolytic system by as much as 1.5 pH units for L. casei and up to 0.5 pH unit for A. viscosus. L. casei cells were inherently somewhat more resistant to severe acid damage than were A. viscosus cells, in that Mg release from L. casei cells in medium with a pH of 3.0 occurred only after a lag of some 4 h, compared with rapid release from A. viscosus cells. However, the major differences pertinent to the physiology of the organisms appeared to be related to proton-translocating ATPases. Isolated membranes of L. casei had about 3.29 U of ATPase per mg of protein, compared with only about 0.06 U per mg of protein for those of A. viscosus. Moreover, the ATPase of L. casei had a pH optimum for hydrolytic activity of about 5, compared with an optimal pH of about 7 for that of A. viscosus.(ABSTRACT TRUNCATED AT 250 WORDS)
Diel Vertical Movements of the Cyanobacterium
Oscillatoria terebriformis
in a Sulfide-Rich Hot Spring Microbial Mat
Authors: Richardson Laurie L. , Castenholz Richard W.
Published: January 2020

Oscillatoria terebriformis,
a thermophilic cyanobacterium, carried out a diel vertical movement pattern in Hunter's Hot Springs, Oreg. Throughout most daylight hours, populations of
O. terebriformis
covered the surface of microbial mats in the hot spring outflows below an upper temperature limit of 54°C. Upon darkness trichomes moved downward by gliding motility into the substrate to a depth of 0.5 to 1.0 mm, where the population remained until dawn. At dawn the population rapidly returned to the top of the mats. Field studies with microelectrodes showed that the dense population of
O. terebriformis
moved each night across an oxygen-sulfide interface, entering a microenvironment which was anaerobic and reducing, a dramatic contrast to the daytime environment at the mat surface where oxygenic photosynthesis resulted in supersaturated O
2
. Laboratory experiments on motility with the use of sulfide gradients produced in agar revealed a negative response to sulfide at concentrations similar to those found in the natural mats. The motility response may help explain the presence of
O. terebriformis
below the mat surface at night. The movement back to the surface at dawn appears to be due to a combination of phototaxis, photokinesis, and the onset of oxygenic photosynthesis which consumes sulfide.
Enhanced Survival of the Cyanobacterium
Oscillatoria terebriformis
in Darkness under Anaerobic Conditions
Authors: Richardson Laurie L. , Castenholz Richard W.
Published: January 2020

Oscillatoria terebriformis
, a thermophilic cyanobacterium, maintained viability in darkness under anaerobic conditions by fermenting exogenous glucose or fructose to lactic acid. The time period of survival was greatly extended when the environmental redox potential was lowered by the addition of sodium thioglycolate or titanium(III) citrate. When exposed to aerobic conditions in darkness, many trichomes underwent lysis in 6 h, and death of all cells occurred in 2 to 3 days. The endogenous aerobic respiration rate was high, and the limited dark aerobic survival period appeared to be due to depletion of stored glycogen. Fructose or glucose did not support or increase aerobic respiration in darkness or lengthen aerobic survival time. Enhanced survival of
O. terebriformis
in darkness under anaerobic, reducing conditions correlates well with the natural nighttime position of this species within sulfide-rich microbial mats associated with hot springs of western North America.
Antimicrobial activity of lysozyme against bacteria involved in food spoilage and food-borne disease
Authors: Hughey V L , Johnson E A
Published: January 2020

Egg white lysozyme was demonstrated to have antibacterial activity against organisms of concern in food safety, including Listeria monocytogenes and certain strains of Clostridium botulinum. We also found that the food spoilage thermophile Clostridium thermosaccharolyticum was highly susceptible to lysozyme and confirmed that the spoilage organisms Bacillus stearothermophilus and Clostridium tyrobutyricum were also extremely sensitive. Several gram-positive and gram-negative pathogens isolated from food poisoning outbreaks, including Bacillus cereus, Clostridium perfringens, Staphylococcus aureus, Campylobacter jejuni, Escherichia coli O157:H7, Salmonella typhimurium, and Yersinia enterocolitica, were all resistant. The results of this study suggest that lysozyme may have selected applications in food preservation, especially when thermophilic sporeformers are problems, and as a safeguard against food poisoning caused by C. botulinum and L. monocytogenes.
Microbial coagulation of alfalfa green juice
Authors: Godessart N , Pares R , Juarez A
Published: January 2020

Of the different bacterial strains isolated from alfalfa raw material, nine were able to coagulate the protein fraction of alfalfa green juice. The two strains showing the highest efficiency were further used for coagulation experiments. They were classified as Erwinia carotovora and Escherichia coli. Juice samples inoculated (1:10 to 1:100) with stationary-phase cultures were efficiently coagulated. The amount of protein recovered was equivalent to that obtained when the juice was heat treated. A minimal incubation temperature of 30 degrees C was required. The protein coagulum appeared after 8 to 10 h of incubation. During this period no bacterial growth was apparent, but glucose was actively fermented. For both strains no extracellular enzymatic activity could be shown in the culture supernatants. The fermentative metabolism during the incubation period seems to be responsible for protein coagulation.
A Study of 33 Bacteriophages of
Rhizobium meliloti
Authors: Werquin Michel , Ackermann Hans-Wolfang , Levesque Roger C.
Published: January 2020

A total of 33
Rhizobium meliloti
bacteriophages were studied. Of those, 21 were isolated in northern France from field soil in which
Medicago sativa
L. was grown. The other 12 phages were obtained by UV light and mitomycin C induction from 46
R. meliloti
strains. Rhizobiophages were characterized by their morphology, host range, serological properties, restriction endonuclease patterns, DNA-DNA homologies, and DNA molecular weights. Five morphotypes were observed showing tailed phages with icosahedral heads. The categories of morphotypes included the
Myoviridae
(11 phages),
Siphoviridae
(3 morphotypes and 20 phages), and
Podoviridae
(2 phages). Type NM1 phage (
Siphoviridae
) is highly unusual because of the presence of transverse bars on the phage tail. Soil phages had broad host ranges, whereas phages isolated from bacterial cultures showed more or less narrow host ranges. Restriction endonuclease patterns and DNA-DNA hybridization experiments showed that the five phage type genomes were unrelated. Molecular weights of phage type DNAs were estimated, and they corresponded to values expected for capsid sizes, except for phage NM8. Type φM11S (
Siphoviridae
) did not correspond to any other described
Rhizobium
phages and represents a new species.
Characterization of
Clostridium thermocellum
JW20
Authors: Freier Doris , Mothershed Cheryle P. , Wiegel Juergen
Published: January 2020

Clostridium thermocellum
JW20 (ATCC 31549), which was isolated from a Louisiana cotton bale, grew on cellulose, cellobiose, and xylooligomers and, after adaptation, on glucose, fructose, and xylose in the pH range of 7.5 to 6.1 with
T
opt
of 60�C,
T
max
of 69�C, and
T
min
of above 28�C. Doubling times during growth on cellulose and cellobiose were 6.5 and 2.5 h, respectively. The G+C content of the DNA was 40 mol% (chemical analysis). Growth on cellulose as substrate was totally inhibited in the presence of more than 125 mM sodium sulfate, 300 mM sodium chloride, 250 mM potassium chloride, 200 mM calcium chloride, 125 mM magnesium chloride, 40 mM lactate, or 250 mM acetate. The ratio of the fermentation products ethanol to acetate plus H
2
decreased when the culture was agitated. Agitation otherwise increased the rate of cellulose degradation in a growing culture but not under nongrowth conditions or with cell-free culture supernatant containing the extracellular cellulase. Shaking lowered the concentration of H
2
in the culture broth and thus minimized inhibition by the H
2
formed. Externally added H
2
caused an increased formation of ethanol during growth on cellulose or cellobiose. However, at an atmospheric pressure as high as 355 kPa (50 lb/in
2
), H
2
did not cause significant growth inhibition beyond an increasing lag phase (up to 24 h). Several criteria to specifically prove the purity of
C. thermocellum
cultures were suggested.
34S/32S fractionation in sulfur cycles catalyzed by anaerobic bacteria
Authors: Fry B , Gest H , Hayes J M
Published: January 2020

Stable isotopic distributions in the sulfur cycle were studied with pure and mixed cultures of the anaerobic bacteria, Chlorobium vibrioforme and Desulfovibrio vulgaris. D. vulgaris and C. vibrioforme can catalyze three reactions constituting a complete anaerobic sulfur cycle: reduction of sulfate to sulfide (D. vulgaris), oxidation of sulfide to elemental sulfur (C. vibrioforme), and oxidation of sulfur to sulfate (C. vibrioforme). In all experiments, the first and last reactions favored concentration of the light 32S isotope in products (isotopic fractionation factor epsilon = -7.2 and -1.7%, respectively), whereas oxidation of sulfide favored concentration of the heavy 34S isotope in products (epsilon = +1.7%). Experimental results and model calculations suggest that elemental sulfur enriched in 34S versus sulfide may be a biogeochemical marker for the presence of sulfide-oxidizing bacteria in modern and ancient environments.
Growth of Indigenous
Rhizobium leguminosarum
and
Rhizobium meliloti
in Soils Amended with Organic Nutrients
Authors: Germida James J.
Published: January 2020

The ability of indigenous
Rhizobium leguminosarum
and
Rhizobium meliloti
to use organic nutrients as growth substrates in soil was assessed by indirect bacteriophage analysis. A total of 17 organic compounds, including 9 carbohydrates, 3 organic acids, and 5 amino acids, were tested (1,000 μg g
−1
) in three soils with different cropping histories. Four additional soils were screened with a glucose amendment. Nutrient amendments stimulated growth of indigenous rhizobia, allowing subsequent replication of indigenous bacteriophages. Phage populations were enumerated by plating soil extracts on 19
R. leguminosarum
and 9
R. meliloti
indicator strains, including root nodule isolates from the soils assayed. On the basis of indirect phage analysis, all soils contained native rhizobia similar to one or more of the indicator strains, although not all indicator strains were detected in soil. All organic compounds stimulated growth of indigenous rhizobia, but the growth response varied for each rhizobial strain depending on the nutrient, the nutrient concentration, and the soil. Indigenous rhizobia readily utilized most organic compounds except phenylalanine, glycine, and aspartic acid. The ability of indigenous rhizobia to utilize a wide range of organic compounds as growth substrates in situ indicates their ability to successfully compete with other soil bacteria for nutrients in these soils.
Structural relatedness between mosquitocidal endotoxins of Bacillus thuringiensis subsp. israelensis
Authors: Garduno F , Thorne L , Walfield A M , Pollock T J
Published: January 2020

A mosquitocidal toxin gene, cloned from Bacillus thuringiensis subsp. israelensis, was introduced into mutant crystal-negative B. thuringiensis subsp. israelensis cells. Partial toxicity to mosquitos was restored. The 58-kilodalton cloned gene product is a minor protein component of B. thuringiensis subsp. israelensis crystals and is structurally related to a major, 135-kilodalton crystal toxin.
Cloning and Gene Replacement Mutagenesis of a
Pseudomonas atlantica
Agarase Gene
Authors: Belas Robert , Bartlett Douglas , Silverman Michael
Published: January 2020

An agarase gene (
agrA
) was isolated by cloning genomic DNA prepared from
Pseudomonas atlantica
. The agarase activity in recombinant
Escherichia coli
was found in cell-free culture supernatants and could pass through a 0.45-μm-pore-size membrane separating cells from agar, suggesting that the gene product was exported in
E. coli
. The enzyme was specific for agar and agarose and did not digest alginate or carrageenan. Mutations generated by transposon mini-Mu d1(
lacZ
Km
r
) were used to define the
agrA
coding region, as well as the direction of transcription of the gene. A procedure was developed to produce a
P. atlantica agrA
mutant. This required construction of an
agrA::kan
insertion mutation in vitro and subsequent introduction of the defect into the chromosome of
P. atlantica
by recombinational exchange. Transformation of
P. atlantica
with plasmids containing
agrA::kan
utilized a Tris-polyethylene glycol 6000-CaCl
2
treatment for making competent cells. Replacement of wild-type
agrA
with
agrA::kan
resulted in loss of agarase activity. Uses of the
agrA
gene probe and an Agr
−
mutant for environmental studies are discussed.
Environmental factors affecting indole metabolism under anaerobic conditions
Authors: Madsen E L , Francis A J , Bollag J M
Published: January 2020

The influence of physiological and environmental factors on the accumulation of oxindole during anaerobic indole metabolism was investigated by high-performance liquid chromatography. Under methanogenic conditions, indole was temporarily converted to oxindole in stoichiometric amounts in media inoculated with three freshwater sediments and an organic soil. In media inoculated with methanogenic sewage sludge, the modest amounts of oxindole detected at 35 degrees C reached higher concentrations and persisted longer when the incubation temperature was decreased from 35 to 15 degrees C. Also, decreasing the concentration of sewage sludge used as an inoculum from 50 to 1% caused an increase in the accumulation of oxindole from 10 to 75% of the indole added. Under denitrifying conditions, regardless of the concentration or source of the inoculum, oxindole appeared in trace amounts but did not accumulate during indole metabolism. In addition, denitrifying consortia which previously metabolized indole degraded oxindole with no lag period. Our data suggest that oxindole accumulation under methanogenic, but not under denitrifying conditions is caused by differences between relative rates of oxindole production and destruction.