bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of bacterial plasmids in clean and polluted sites in a South Wales river
Authors: Burton N F , Day M J , Bull A T
Published: January 2020

We isolated 400 aerobic heterotrophic bacteria from the sediment of unpolluted and polluted sites in a fast-flowing south Wales river. Isolates were subjected to taxonomic tests and screened for the presence of plasmid DNA by alkaline lysis and agarose gel techniques. There were no significant differences between sites in either the total percentage of isolates containing plasmids (unpolluted site, 9.4%; polluted site, 15%) or in the percentage of non-Pseudomonas-like isolates containing plasmids (unpolluted site, 15%; polluted site, 10%). There were significantly more Pseudomonas-like isolates with plasmids at the polluted site than at the unpolluted site (unpolluted site, 7%; polluted site, 18%). This presumably reflected a response of the nutritionally versatile Pseudomonas-like isolates to conditions at that site. The majority (86%) of the plasmids detected had molecular masses between 35 and 312 megadaltons. These plasmids were large enough to carry genes for conjugal transfer, suggesting the possibility of such transfer in this environment.
Effects of temperature and salinity on Vibrio cholerae growth
Authors: Singleton F L , Attwell R , Jangi S , Colwell R R
Published: January 2020

Laboratory microecosystems (microcosms) prepared with a chemically defined sea salt solution were used to study effects of selected environmental parameters on growth and activity of Vibrio cholerae. Growth responses under simulated estuarine conditions of 10 strains of V. cholerae, including clinical and environmental isolates as well as serovars O1 and non-O1, were compared, and all strains yielded populations of approximately the same final size. Effects of salinity and temperature on extended survival of V. cholerae demonstrated that, at an estuarine salinity (25%) and a temperature of 10 degrees C, V. cholerae survived (i.e., was culturable) for less than 4 days. Salinity was also found to influence activity, as measured by uptake of 14C-amino acids. Studies on the effect of selected ions on growth and activity of V. cholerae demonstrated that Na+ was required for growth. The results of this study further support the status of V. cholerae as an estuarine bacterium.
Survival of Campylobacter jejuni inoculated into ground beef
Authors: Stern N J , Kotula A W
Published: January 2020

Ground beef was inoculated with mixed cultures of Campylobacter jejuni, and the samples were subjected to various cooking and cold-storage temperatures. When samples were heated in an oven at either 190 or 218 degrees C, approximately 10(7) cells of C. jejuni per g were inactivated (less than 30 cells per g) in less than 10 min after the ground beef reached an internal temperature of 70 degrees C. When the samples were held at -15 degrees C over 14 days of storage, the numbers of C. jejuni declined by 3 log10. When inoculated samples were stored with an equal amount of Cary-Blair diluent at 4 degrees C, no changes in viability were observed over 14 days of storage. Twenty-five times as much C. jejuni was recovered from inoculated ground beef when either 10% glycerol or 10% dimethyl sulfoxide was added to an equal amount of ground beef before freezing as was recovered from peptone-diluted ground beef. Twice as much inoculated C. jejuni was recovered from ground beef plus Cary-Blair diluent as was recovered from ground beef plus peptone diluent.
Preservation of Estuarine Sediments for Lipid Analysis of Biomass and Community Structure of Microbiota
Authors: Federle Thomas W. , White David C.
Published: January 2020

Various methods were tested for preserving estuarine sediments in the field before biochemical analysis of the microbiota. Total microbial biomass was determined as lipid phosphate (LP), and the fatty acids of the microbial lipids were used as indicators of community structure. Control samples were sieved to remove macroinvertebrates and plant materials and were extracted immediately in the field. Other samples were preserved both before and after sieving and stored for 5 days before analysis. Freezing resulted in a 50% decline in LP and significant decreases in many fatty acids. Refrigeration resulted in a 19% decrease in LP but no change in the fatty acids. Samples preserved with Formalin before sieving exhibited no significant change in LP but substantial increases in many fatty acids, which were probably derived from the macroinvertebrates. Sieved samples preserved with Formalin showed a 17 to 18% decline in LP but no change in the fatty acids. Ideally, samples should be sieved and extracted immediately in the field. However, short-term refrigeration and longer-term preservation of sieved samples with Formalin may be acceptable compromises.
Absence of surface-associated microorganisms in adult oysters (Crassostrea gigas)
Authors: Garland C D , Nash G V , McMeekin T A
Published: January 2020

Healthy, actively feeding intertidal oysters were removed from an estuarine environment (Pipeclay Lagoon, Tasmania). The epithelial surfaces of various organs of the mantle cavity and alimentary tract were explored by scanning and transmission electron microscopy. All epithelial tissues examined were ciliated, and nearly all were partly covered with secreted mucus. However, microorganisms were seen rarely in the adhesive mucus and never attached to the epithelium. Electron microscopy also failed to demonstrate a surface microflora in emersed oysters which had been incubated at 5 to 25 degrees C for 6 or 24 h. The absence of an internal surface microflora did not vary on a seasonal basis. In laboratory experiments, oysters were allowed to filter feed from seawater containing diverse types of marine bacteria at concentrations of 10(3) to 10(7)/mL. However, no surface microflora could be found within actively feeding oysters or in emersed animals incubated at 20 degrees C for 6 or 24 h. In contrast, surface-associated microorganisms were detected readily by scanning electron microscopy on the external shell of healthy oysters and on various internal tissues in spoiled oysters. It is suggested that the major mechanisms restricting microbial growth within oysters are ciliary movement and mucus secretion.
Comparison of the Pour, Spread, and Drop Plate Methods for Enumeration of
Rhizobium
spp. in Inoculants Made from Presterilized Peat
Authors: Hoben H. J. , Somasegaran P.
Published: January 2020

Inoculants prepared with presterilized peat were enumerated by the pour, spread, and drop plate techniques. Results indicated that the three plating methods were interchangeable. The drop plate method was preferred because of its economy in materials and labor.
Application of flow cytometry to studies of pathogenic free-living amoebae
Authors: Muldrow L L , Tyndall R L , Fliermans C B
Published: January 2020

Species of small, free-living amoebae of the genera Naegleria and Acanthamoeba can cause fatal amoebic meningoencephalitis. Previous investigations have shown that pathogenic amoebae are associated with thermally altered water. Flow cytometric techniques for identifying species of pathogenic and nonpathogenic amoebae from such water have been developed, using immunofluorescence and fluorescein-bound concanavalin A. Flow cytometry is accomplished with a cytofluorograph, in which cells are dispersed in a suspended carrier liquid and passed in front of a focused argon ion laser beam. Cells are then distinguished by the degree of scattered light (size) or fluorescence. Flow cytometry techniques have proven efficient for environmental samples, as indicated by the identification of pathogenic Naegleria fowleri and nonpathogenic Naegleri gruberi and Acanthamoeba castellanii isolated from the Savannah River Plant in South Carolina. Cytofluorographic analysis of environmental samples has several advantages over the current methods of isolation and classification of free-living amoebae. With this system, it is possible to rapidly identify species and quantitate mixtures of pathogenic amoebae in environmental samples. Cytofluorographic analysis of amoebic isolates reduces the time presently required to screen environmental sites for pathogenic amoebae. The cytofluorograph permits detection and species identification of nonthermophilic Naegleria spp. and Acanthamoeba spp. that could not easily be isolated for species identification by conventional methods. Other advantages of flow cytometry over fluorescent microscopy include a high degree of statistical precision due to the large numbers measured, high immunofluorescent titers, and elimination of subjectivity and fluorescence fading.
Influence of Temperature Adaptation on Glucose Metabolism in a Psychrotrophic Strain of
Cytophaga johnsonae
Authors: Reichardt Wolfgang , Morita Richard Y.
Published: January 2020

Selective enrichment of yellow-orange-pigmented, gram-negative bacteria related to
Cytophaga johnsonae
from lake sediment was dependent on low temperatures (ca. 5°C). However, this temperature effect was abolished when excessive amounts of dissolved organic carbon (10 mM
N
-acetylglucosamine) were added. A psychrotrophic freshwater isolate of
C. johnsonae
was used to study the physiological versatility of this group. Exponential growth rates were found to be dependent on the temperature to which the cells used as the inocula were acclimated. Glucose incorporation and respiration were also dependent upon the acclimation temperature of the inocula. Patterns of
14
CO
2
evolution obtained from position-labeled [
14
C]glucose indicated that glucose was predominantly metabolized via the Embden-Meyerhof-Parnas pathway, which, however, was greatly reduced at 25°C when the concentration of glucose was as low as 5 μM/liter. Transport, respiration, and incorporation of glucose (0.2- to 20,000-μM/liter concentrations) into macromolecular cellular compounds were characterized by multiple

K
m

values which were a function of substrate concentration and temperature. It appeared possible that these multiple

K
m

values reflected the changing participation of the Embden-Meyerhof-Parnas pathway in glucose metabolism. These results may provide a physiological explanation for the selective enrichment of psychrotrophic freshwater cytophagas. Moreover, they exhibit the limits of interpreting kinetic data based on conventional heterotrophic potential measurements, especially when some complications may arise from temperature and substrate adaptations of the more versatile members of the chemoorganotrophic microflora such as
C. johnsonae.
Efficacy of ozone in eradication of Legionella pneumophila from hospital plumbing fixtures
Authors: Edelstein P H , Whittaker R E , Kreiling R L , Howell C L
Published: January 2020

The effect of ozonation of supply water for one wing of an unoccupied hospital building which had positive cultures for Legionella pneumophila from multiple potable water fixtures was studied in a prospective, controlled fashion. Mean ozone residual concentrations of 0.79 mg/liter eradicated L. pneumophila from the fixtures, but so did nonozonated water in the control wing fixtures. The efficacy of the nonozonated water was most probably due to a mechanical flushing effect and to an unexpected rise in the chlorine content of the supply water. Determination of the in vitro activity of ozone against L. pneumophila did not predict the efficacy of its eradication from water fixtures treated with ozone.
Exopolysaccharide Distribution of and Bioemulsifier Production by
Acinetobacter calcoaceticus
BD4 and BD413
Authors: Kaplan Nachum , Rosenberg Eugene
Published: January 2020

The heavily encapsulated
Acinetobacter calcoaceticus
BD4 and the “miniencapsulated” single-step mutant
A. calcoaceticus
BD413 produced extracellular polysaccharides in addition to the capsular material. The molar ratio of rhamnose to glucose (3:1) in the extracellular BD413 polysaccharide fraction was similar to the composition of the capsular material. In both strains, the increase in capsular polysaccharide was parallel to cell growth and remained constant in stationary phase. The extracellular polysaccharides were detected starting from mid-logarithmic phase and continued to accumulate in the growth medium for 5 to 8 h after the onset of stationary phase. Strain BD413 produced one-fourth the total rhamnose exopolysaccharide per cell that strain BD4 did. Depending on the growth medium, 32 to 63% of the rhamnose polysaccharide produced by strain BD413 was extracellular, whereas in strain BD4 only 7 to 14% was extracellular. In all cases, strain BD413 produced more extracellular rhamnose polysaccharide than strain BD4 did. In glucose medium, strain BD413 also produced approximately 10 times more extracellular emulsifying activity than strain BD4 did. The isolated capsular polysaccharide obtained after shearing of BD4 cells showed no emulsifying activity. Thus, strain BD413 either produces a modified extracellular polysaccharide or excretes an additional substance(s) that is responsible for the emulsifying activity. Emulsions induced by the ammonium sulfate-precipitated BD413 extracellular emulsifier require the presence of magnesium ion and a mixture of an aliphatic and an aromatic hydrocarbon.
Enzyme-linked immunosorbent assay for detection of staphylococcal enterotoxins in foods
Authors: Freed R C , Evenson M L , Reiser R F , Bergdoll M S
Published: January 2020

An enzyme-linked immunosorbent assay (ELISA) was developed for detection of staphylococcal enterotoxins in foods. The "double-antibody sandwich" protocol combines parts of several procedures reported previously. Horseradish peroxidase was conjugated to antibody specific for an enterotoxin, and the antibody-enzyme conjugate was assayed with a 2,2'-azino-di-(3-ethylbenzthiazoline sulfonic acid)-H2O2 substrate solution. Enterotoxins were added to a variety of foods that were representative of those implicated in staphylococcal food poisoning outbreaks. Extracts of the foods were assayed by the ELISA and radioimmunoassay. Enterotoxin levels below 1 ng/g of food were consistently detectable by the ELISA. These results compared favorably with those of the radioimmunoassay. Experiments confirmed the interference of protein A in double-antibody sandwich ELISAs. Although protein A interference has not been demonstrated to be a problem in food extracts, we suggest a screen for protein A interference in which immunoglobulin G from nonimmunized rabbits is used. All of the known staphylococcal enterotoxins could be detected by this method. Analysis of a food product for entertoxin by the ELISA can be completed in an 8-h working day.
Nitrite and Nitric Oxide as Inhibitors of Nitrogenase from Soybean Bacteroids
Authors: Trinchant Jean-Charles , Rigaud J.
Published: January 2020

Nitrite was able to strongly inhibit C
2
H
2
reduction by nitrogenase from soybean bacteroids, whereas H
2
evolution was unaffected under the same conditions. NO inhibited both C
2
H
2
reduction and H
2
evolution; during C
2
H
2
reduction, sensitivity of nitrogenase to NO was higher than to NO
2
−
, and the
K

i

values were, respectively, 0.056 and 0.52 mM. Production of NO resulting from a reduction of NO
2
−
by dithionite in nitrogenase incubations was observed. However, the characteristics of inhibitions and the low level of NO generated by nitrite reduction ruled out the suggestion concerning a direct role of NO to explain the inhibitory effect of NO
2
−
on nitrogenase.
Recovery of viruses from vegetable surfaces
Authors: Ward B K , Chenoweth C M , Irving L G
Published: January 2020

The efficiency of a system developed for the recovery of viruses contaminating large quantities of vegetables was investigated in the laboratory and tested in the field. Viruses seeded onto a number of leafy vegetables in the laboratory were eluted with a phosphate-buffered saline solution (pH 9.0). The eluate was clarified by glass wool filtration, and any viruses present were concentrated by adsorption to a Filterite pleated cartridge filter, eluted with 3% beef extract (pH 9.0), and further concentrated by organic flocculation. At least 24 liters of vegetable eluate could be concentrated to 70 to 80 ml, equivalent to a greater than 99.5% reduction in volume. With this system, poliovirus was recovered with a mean efficiency of 58% for all vegetables tested. Adenovirus was recovered from lettuce with a slightly lower mean efficiency (55%). Poliovirus was recovered from large quantities of cabbage for up to 5 days in the field after spray irrigation of relatively low levels of virus, even when heavy rain fell before sampling.
Distribution and ecology of Vibrio vulnificus and other lactose-fermenting marine vibrios in coastal waters of the southeastern United States
Authors: Oliver J D , Warner R A , Cleland D R
Published: January 2020

Water, sediment, plankton, and animal samples from five coastal sites from North Carolina to Georgia were sampled for their lactose-fermenting vibrio populations. Over 20% of all vibrios tested were sucrose negative and o-nitrophenyl-beta-D-galactopyranoside (ONPG) positive, suggesting identification as the human pathogen Vibrio vulnificus. These vibrios were isolated from all sample sites and sources (water, sediment, plankton, and animals). Correlations with several of 19 environmental parameters monitored at each site were found for total vibrios. The presence of ONPG-positive, sucrose-negative vibrios was correlated with hydrocarbon levels in the water and, in the case of plankton samples, with salinity. A total of 279 sucrose-negative, ONPG-positive isolates were subjected to numerical taxonomic analysis, which resulted in three major clusters. Cluster I corresponded to and included 11 reference strains of V. vulnificus. Cluster II contained the largest number (133) of isolates, of which the great majority were bioluminescent. Although having a resemblance to V. harveyi, the isolates were ONPG positive and many were H2S positive. Cluster III consisted of strains similar to the group F vibrios (V. fluvialis). Of all of the isolates, 55% were luminescent, of which over 20% were lethal when injected into mice. Problems involved in detecting lactose fermentation among marine vibrios and the potential pathogenicity of these organisms are discussed.
Isolation and characterization of a pentachlorophenol-degrading bacterium
Authors: Stanlake G J , Finn R K
Published: January 2020

With a new enrichment protocol, pentachlorophenol (PCP)-degrading bacteria were isolated from soil, water, and sewage. When characterized, all isolates were related and shared characteristics of the genus Arthrobacter. Growth rates for strain NC were determined for a number of substrates, including PCP and 2,4,6-trichlorophenol. Changes in PCP concentration affected growth rate and length of the lag phase but not cell yield. Increasing the pH from 6.8 to 7.8 decreased the length of the lag phase for growth on PCP. Cessation of growth, upon incremental addition of PCP, was found to be related to a decrease in pH rather than to a buildup of a toxic metabolite. Degradation of PCP by strain NC was shown to be complete.
Cellulolytic and non-cellulolytic bacteria in rat gastrointestinal tracts
Authors: Macy J M , Farrand J R , Montgomery L
Published: January 2020

Lactobacillus and Bifidobacterium species were the predominant organisms isolated from small intestinal (jejunal) contents of rats, and lactic acid was the only organic acid detected. The numbers of cellulolytic bacteria in small intestines were low (approximately 10(3)/g). The fermentation in ceca was different from that in intestines, as, in addition to small amounts of lactic acid, high concentrations of volatile fatty acids were detected. The mixed cecal microflora was able to digest cellulose (pebble-milled Whatman no. 1) and cabbage. High numbers of cellulolytic bacteria were found (0.5 X 10(8) to 12.2 X 10(8)/g; 6% of total viable bacteria). The predominant celluloytic organism isolated was Bacteroides succinogenes. Ruminococcus flavifaciens was isolated from a few animals. The kinds and numbers of the predominant non-cellulolytic organisms isolated from rat ceca were similar to those described by previous workers.
Uptake of Branched-Chain Amino Acids by
Streptococcus thermophilus
Authors: Akpemado K. M. , Bracquart P. A.
Published: January 2020

The transport of branched-chain amino acids in
Streptococcus thermophilus
was energy dependent. The metabolic inhibitors of glycolysis and ATPase enzymes were active, but the proton-conducting uncouplers were not. Transport was optimal at temperatures of between 30 and 45°C and at pH 7.0 for the three amino acids leucine, valine, and isoleucine; a second peak existed at pH 5.0 with valine and isoleucine. By competition and kinetics studies, the branched-chain amino acids were found to share at least a common transport system.
Cooperative formation of omega-muricholic acid by intestinal microorganisms
Authors: Eyssen H , De Pauw G , Stragier J , Verhulst A
Published: January 2020

Three anaerobic bacteria, isolated from the ceca of rats and mice, converted, through a concerted mechanism, beta-muricholic acid, the predominant bile acid in germfree rats, into omega-muricholic acid. One isolate was a Eubacterium lentum strain; the second and third isolates were tentatively identified as atypical Fusobacterium sp. strains. The conversion of beta-muricholic acid into omega-muricholic acid proceeded in two steps: E. lentum oxidized the 6 beta-hydroxyl group of beta-muricholic acid to a 6-oxo group, which was reduced by either of the two other species to a 6 alpha-hydroxyl group, yielding omega-muricholic acid. This transformation occurred both in vitro and in gnotobiotic rats. Monoassociation of germfree rats with the E. lentum strain gave rise to an unidentified fecal bile acid, probably a derivative of beta-muricholic acid having a double bond in the side chain.
Serological method for identification of Vibrio parahaemolyticus from marine samples
Authors: Shinoda S , Nakahara N , Ninomiya Y , Itoh K , Kane H
Published: January 2020

Use of agglutination with antiserum against lateral flagella (H-agglutination) for the identification of Vibrio parahaemolyticus was studied. Sucrose-negative bacteria were isolated from seawater, and their characterization was carried out by traditional biological tests and slide agglutination with antiserum specific to lateral flagella of V. parahaemolyticus. Of 135 strains isolated, 78 were identified as V. parahaemolyticus by biological tests and were agglutinated with the above serum. Fifty-five strains did not agglutinate with the serum, and their biological characteristics were different from those of V. parahaemolyticus. Two strains also differed from V. parahaemolyticus in some biological characteristics but agglutinated with the antiserum. All clinically isolated V. parahaemolyticus strains also agglutinated with the above serum. These results suggest that our serological method is useful for the identification of V. parahaemolyticus, especially for samples in which there are many organisms related to V. parahaemolyticus, because many biological tests can be omitted.
Methanogenesis from Choline by a Coculture of
Desulfovibrio
sp. and
Methanosarcina barkeri
Authors: Fiebig K. , Gottschalk G.
Published: January 2020

A sulfate-reducing vibrio was isolated from a methanogenic enrichment with choline as the sole added organic substrate. This organism was identified as a member of the genus
Desulfovibrio
and was designated
Desulfovibrio
strain G1. In a defined medium devoid of sulfate, a pure culture of
Desulfovibrio
strain G1 fermented choline to trimethylamine, acetate, and ethanol. In the presence of sulfate, more acetate and less ethanol were formed from choline than in the absence of sulfate. When grown in a medium containing sulfate, a coculture of
Desulfovibrio
strain G1 and
Methanosarcina barkeri
strain Fusaro degraded choline almost completely to methane, ammonia, and hydrogen sulfide and presumably to carbon dioxide. Methanogenesis occurred in two distinct phases separated by a lag of about 6 days. During the first phase of methanogenesis choline was completely converted to trimethylamine, acetate, hydrogen sulfide, and traces of ethanol by the desulfovibrio.
M. barkeri
fermented trimethylamine to methane, ammonia, and presumably carbon dioxide via dimethyl- and methylamine as intermediates. Simultaneously, about 60% of the acetate expected was metabolized. In the second phase of methanogenesis, the residual acetate was almost completely catabolized.
Chlorine Demand and Inactivation of Fungal Propagules
Authors: Rosenzweig W. D. , Minnigh H. A. , Pipes W. O.
Published: January 2020

Conidia of filamentous fungi, vegetative yeast cells, and coliform bacteria were tested to determine their chlorine demand and their sensitivity to chlorine inactivation. Levels of chlorine demand for the various conidia, yeast, and coliforms were, respectively, 3.6 × 10
−9
to 3.2 × 10
−8
, 1.2 × 10
−9
to 8.0 × 10
−9
, and 2.5 × 10
−11
to 6.3 × 10
−10
mg of chlorine per propagule. Preliminary evidence suggests that the chlorine demand per propagule increases as the number of propagules per milliliter decreases. In general, conidia showed greatest resistance to chlorine inactiviation, followed by the yeast and coliforms. Inactivation by chlorine was influenced by pH, with inactivation (chlorine activity) falling in the order pH 5 > 7 > 8.
Medium-dependent production of extracellular enterotoxins by non-O-1 Vibrio cholerae, Vibrio mimicus, and Vibrio fluvialis
Authors: Nishibuchi M , Seidler R J
Published: January 2020

Fluid accumulation at 4 h in the intestines of suckling mice enabled us to distinguish non-O-1 Vibrio cholerae, V. mimicus, and V. fluvialis clinical isolates from environmental isolates. Enterotoxin production was culture medium dependent. Filtrates of cultures grown in tryptic soy broth without glucose but with added 0.5% NaCl did not exhibit marked enterotoxin activity in the assay. Culture filtrates of all clinical strains grown in brain heart infusion broth supplemented with 0.5% NaCl induced large amounts of fluid accumulation in mouse intestines. However, most environmental strains grown in brain heart infusion broth amended as described above were unable to induce fluid accumulation. The enterotoxin present in culture filtrates lost activity at 56 degrees C and appeared to be distinct from previously described virulence factors, including the well-described cholera toxin. The new enterotoxin could represent an important virulence mechanism common to all three species.
Improvements in and Environmental Applications of Double-Vial Radiorespirometry for the Study of Microbial Mineralization
Authors: McKinley Vicky L. , Federle Thomas W. , Vestal J. Robie
Published: January 2020

Several variations in the scintillation mixture and the filter paper arrangements for double-vial radiorespirometry were compared. Improved efficiencies (44%) and shorter response times were found by adding wetting agents and methanolic NaOH to the scintillation mixture in the filter paper. The scintillation chemicals used did not contain dioxane and were found to be nontoxic to the test microbiota in this system. Covering the inner reaction vial with aluminum foil minimized the reduction in counting efficiency when testing colored or dense environmental samples. Mineralization rates were determined with
14
C-labeled glucose, acetate, and glutamate and [
14
C]cellulose- and [
14
C]lignin-labeled lignocellulose for composting cow manure, forest soil, and arctic lake sediment microbiota. This improved method can be used in a variety of procedures involving the measurement of microbial mineralizations of organic compounds. Since no liquid scintillation cocktail is used for counting, the radioactive wastes are aqueous or can be incinerated, making disposal easy.
Isolation and Characterization of an H
2
-Oxidizing Thermophilic Methanogen
Authors: Ferguson Thomas J. , Mah Robert A.
Published: January 2020

A thermophilic methanogen was isolated from enrichment cultures originally inoculated with sludge from an anaerobic kelp digester (55°C). This isolate exhibited a temperature optimum of 55 to 60°C and a maximum near 70°C. Growth occurred throughout the pH range of 5.5 to 9.0, with optimal growth near pH 7.2. Although 4% salt was present in the isolation medium, salt was not required for optimal growth. The thermophile utilized formate or H
2
-CO
2
but not acetate, methanol, or methylamines for growth and methanogenesis. Growth in complex medium was very rapid, and a minimum doubling time of 1.8 h was recorded in media supplemented with rumen fluid. Growth in defined media required the addition of acetate and an unknown factor(s) from digester supernatant, rumen fluid, or Trypticase. Cells in liquid culture were oval to coccoid, 0.7 to 1.8 μm in diameter, often occurring in pairs. The cells were easily lysed upon exposure to oxygen or 0.08 mg of sodium dodecyl sulfate per ml. The isolate was sensitive to tetracycline and chloramphenicol but not penicillin G or cycloserine. The DNA base composition was 59.69 mol% guanine plus cytosine.
Ecological relationships between Vibrio cholerae and planktonic crustacean copepods
Authors: Huq A , Small E B , West P A , Huq M I , Rahman R , Colwell R R
Published: January 2020

Strains of Vibrio cholerae, both O1 and non-O1 serovars, were found to attach to the surfaces of live copepods maintained in natural water samples collected from the Chesapeake Bay and Bangladesh environs. The specificity of attachment of V. cholerae to live copepods was confirmed by scanning electron microscopy, which revealed that the oral region and egg sac were the most heavily colonized areas of the copepods. In addition, survival of V. cholerae in water was extended in the presence of live copepods. Attachment of viable V. cholerae cells to copepods killed by exposure to -60 degrees C was not observed. Furthermore, survival of V. cholerae was not as long in the presence of dead copepods as in the live copepod system. A strain of Vibrio parahaemolyticus was also seen to attach to copepod surfaces without effect on survival of the organism in water. The attachment of vibrios to copepods was concluded to be significant since strains of other bacteria, including Pseudomonas sp. and Escherichia coli, did not adhere to live or dead copepods. Attachment of V. cholerae to live copepods is suggested to be an important factor of the ecology of this species in the aquatic environment, as well as in the epidemiology of cholera, for which V. cholerae serovar O1 is the causative agent.
Enhancement of the 7α-Dehydroxylase Activity of a Gram-Positive Intestinal Anaerobe by Flavins
Authors: Masuda Noriyuki , Oda Hiroshi , Hirano Seiju , Tanaka Hiromitsu
Published: January 2020

The addition of flavins to the growth medium specifically enhanced the 7α-dehydroxylation of bile acids by anaerobically growing cultures of a
Eubacterium lentum
-like intestinal anaerobe, strain c-25, without an increase in cell growth. The order of the enhancement of the reaction was flavin adenine dinucleotide > flavin mononucleotide ≫ riboflavin.
Enzymatic Inactivation of Residual Gentamicin After Membrane Filtration
Authors: Blank James
Published: January 2020

Residual gentamicin on a Millipore membrane was inactivated by modification with two different enzymes: gentamicin adenylyltransferase and 3-
N
-acetyltransferase. Both modifications allowed the growth of susceptible strains of
Escherichia coli
and
Bacillus subtilis
.
Congo Red Absorption by
Rhizobium leguminosarum
Authors: Kneen Barbara E. , LaRue Thomas A.
Published: January 2020

Congo red absorption is generally considered a contraindication of
Rhizobium
. However,
R. leguminosarum
takes up the dye on yeast extract-mannitol agar. The uptake of congo red varies among strains of
R. leguminosarum
, as shown elsewhere with strains of
R. trifolii
and
R. meliloti
. Congo red absorption does not distinguish rhizobia from other bacteria, but may be useful as a strain marker.
Relationship Between Physiological Status and Formation of Extracellular Polysaccharide Glycocalyx in
Pseudomonas atlantica
Authors: Uhlinger David J. , White David C.
Published: January 2020

Marine pseudomonads, such as
Pseudomonas atlantica
, are readily isolated from sediments. These organisms form extracellular polysaccharide polymers (glycocalyx). The factors affecting the composition and amount of glycocalyx in batch culture of these organisms were examined. The formation of glycocalyx was stimulated by the inclusion of galactose as the carbon source and by increased surface area resulting from addition of sand to the medium. The composition of the glycocalyx changed during the growth cycle, with a marked increase in the proportions and absolute amounts of uronic acids as the rate of synthesis increased. In estuarine sediments, the glycocalyx contained a carbon content at least as great as in the microbes themselves. The greatest accumulation of these polymers occurred late in the stationary phase when the physiological status of the cells, as measured by the adenylate energy charge, showed maximal stress. Maximal formation of glycocalyx possibly could be used as an estimate of the nutritional status of these microbes.
Prevalence of Campylobacter jejuni in two California chicken processing plants
Authors: Wempe J M , Genigeorgis C A , Farver T B , Yusufu H I
Published: January 2020

Two federally inspected California chicken processing plants participated in Campylobacter jejuni prevalence studies. Twelve sampling sites were included in each of four groups. Groups were based on bird age, scald water temperature, and plant sampled. Scald water temperatures of 60 degrees C (140 degrees F) did not contribute to a lower prevalence of C. jejuni in edible parts, as did temperatures of 53 degrees C (127 degrees F) and 49 degrees C (120 degrees F). The feather picker and chilling tank were areas of major cross-contamination. C. jejuni was isolated from 68% of the ready-for-market products. The organism was recovered from 60 to 100% of the ceca in the four groups, and some numbers in the fecal material exceeded 10(6)/g. The level of C. jejuni in intestinal tracts seemed to correlate with the presence of the organism in the edible parts.
Haloperoxidases: Enzymatic Synthesis of α,β-Halohydrins from Gaseous Alkenes
Authors: Geigert John , Neidleman Saul L. , Dalietos Demetrios J. , DeWitt Susanne K.
Published: January 2020

The enzymatic synthesis of α,β-halohydrins from gaseous alkenes is described. The enzymatic reaction required an alkene, a halide ion, dilute hydrogen peroxide, and a haloperoxidase enzyme. A wide range of gaseous alkenes were suitable for this reaction, including those containing isolated, conjugated, and cumulative carbon-carbon double bonds. Chlorohydrins, bromohydrins, and iodohydrins could be formed. The combining of this enzymatic synthesis with a previously described enzymatic synthesis of epoxides from α,β-halohydrins provides an alternate pathway, other than the well-known enzymatic direct epoxidation pathway, from alkene to an epoxide.
Methane Oxidation by
Nitrosococcus oceanus
and
Nitrosomonas europaea
Authors: Jones Ronald D. , Morita Richard Y.
Published: January 2020

Chemolithotrophic ammonium-oxidizing and nitrite-oxidizing bacteria including
Nitrosomonas europaea, Nitrosococcus oceanus, Nitrobacter
sp.,
Nitiospina gracilis
, and
Nitrococcus mobilis
were examined as to their ability to oxidize methane in the absence of ammonium or nitrite. All ammonium oxidizers tested had the ability to oxidize significant amounts of methane to CO
2
and incorporate various amounts into cellular components. None of the nitrite-oxidizing bacteria were capable of methane oxidation. The methane-oxidizing capabilities of
Nitrosococcus oceanus
and
Nitrosomonas europaea
were examined with respect to ammonium and methane concentrations, nitrogen source, and pH. The addition of ammonium stimulated both CO
2
production and cellular incorporation of methane-carbon by both organisms. Less than 0.1 mM CH
4
in solution inhibited the oxidation of ammonium by
Nitrosococcus oceanus
by 87%. Methane concentrations up to 1.0 mM had no inhibitory effects on ammonium oxidation by
Nitrosomonas europaea.
In the absence of NH
4
-N,
Nitrosococcus oceanus
achieved a maximum methane oxidation rate of 2.20 × 10
−2
μmol of CH
4
h
−1
mg (dry weight) of cells
−1
, which remained constant as the methane concentration was increased. In the presence of NH
4
-N (10 ppm [10 μg/ml]), its maximum rate was 26.4 × 10
−2
μmol of CH
4
h
−1
mg (dry weight) of cells
−1
at a methane concentration of 1.19 × 10
−2
mM. Increasing the methane concentration above this level decreased CO
2
production, whereas cellular incorporation of methane-carbon continued to increase.
Nitrosomonas europaea
showed a linear response throughout the test range, with an activity of 196.0 × 10
−2
μmol of CH
4
h
−1
mg (dry weight) of cells
−1
at a methane concentration of 1.38 × 10
−1
mM. Both nitrite and nitrate stimulated the oxidation of methane. The pH range was similar to that for ammonium oxidation, but the points of maximum activity were at lower values for the oxidation of methane.
11β-Hydroxylation of Cortexolone (Reichstein Compound S) to Hydrocortisone by
Curvularia lunata
Entrapped in Photo-Cross-Linked Resin Gels
Authors: Sonomoto Kenji , Hoq M. Mozammel , Tanaka Atsuo , Fukui Saburo
Published: January 2020

Spores of
Curvularia lunata
were immobilized by entrapment with photo-cross-linkable resin prepolymers and incubated to form mycelium in potato dextrose broth containing cortexolone (Reichstein compound S) as an inducer of steroid 11β-hydroxylase. In a buffer system containing 2.5% dimethyl sulfoxide, this immobilized mycelium hydroxylated cortexolone to hydrocortisone. The activity of this mycelium was comparable to the activity of free mycelium. Dimethyl sulfoxide did not inhibit hydroxylase activity at the concentration used and was effective in dissolving the product. Of the various photo-cross-linkable resin prepolymers examined, use of ENT-4000, whose main chain was polyethylene glycol 4000 (chain length, approximately 40 nm), resulted in maximum hydroxylation activity of the entrapped mycelium. The chain length of prepolymers affected markedly mycelial growth in the gels and, subsequently, the activity of the entrapped mycelium. The immobilized hydroxylation system was more stable than the system in free mycelium and could be reactivated by incubation of the entrapped mycelium in potato dextrose broth containing cortexolone. The system was tested 50 times during 100 days of operation and was found to carry out the desired transformation with overall yields of 60%.
Production of Antimicrobial and Bacteriocin-Like Substances by
Rhizobium trifolii
Authors: Joseph M. V. , Desai J. D. , Desai A. J.
Published: January 2020

Rhizobium trifolii
strains IARI and Rel-1 produced substances with broad and narrow activity spectra, respectively. Reproducible inhibitory zones of various sizes produced by
R. trifolii
IARI (2 to 14 mm) and
R. trifolii
Rel-1 (2 to 6 mm) were detected, depending upon the indicator organism used. The maximum production of these substances by both strains of
R. trifolii
was observed on
l
-arabinose agar. A preliminary characterization of the antimicrobial substance produced by strain IARI showed resistance to heat (75 to 80°C for 45 min), trypsin, lysozyme, DNase I, and RNase A. On the other hand, the substance produced by strain Rel-1 showed sensitivity to heat (75 to 80°C for 45 min) and trypsin, but resistance to lysozyme, RNase A, and DNase I.
Nitrogenase Activity (Acetylene Reduction) of Root-Associated, Cold-Climate
Azospirillum, Enterobacter, Klebsiella
, and
Pseudomonas
Species During Growth on Various Carbon Sources and at Various Partial Pressures of Oxygen
Authors: Haahtela Kielo , Kari Kirsti , Sundman Veronica
Published: January 2020

A comprehensive view of the diazotrophic bacterial flora of plants requires that attention be paid to the appropriate carbon and oxygen requirements during isolation of the bacteria. Twenty compounds (monosaccharides, disaccharides, polyols, and organic acids) were therefore examined as carbon and energy sources for nitrogenase activity in semisolid stab cultures at pO
2
values of 0.21, 0.02, and ≤0.002 with 12 strains of diazotrophic root-associated bacteria. With the facultatively anaerobic bacteria of the genera
Klebsiella
and
Enterobacter
, the best substrate was sucrose, followed by fructose and mannitol, whereas among the organic acids, only malic and fumaric acids supported any activity. With the obligately aerobic bacteria of the genera
Azospirillum
and
Pseudomonas
, disaccharides were not utilized for nitrogen fixation, but several organic acids were accepted in addition to monosaccharides and polyols; malate and glucose were the best substrates. The patterns of the carbon sources utilized for nitrogen fixation were coherent within the species, with the exception of one
Klebsiella pneumoniae
and one
Enterobacter agglomerans
strain, both isolated from the same individual grass plant, which were unable to utilize lactose. Anaerobic conditions (pO
2
value of ≤0.002) were required for maximum nitrogenase activity with the facultatively anaerobic bacteria, with the exception of one strain of
E. agglomerans
, which required atmospheric oxygen (pO
2
value of 0.21). Also, the obligately aerobic diazotrophs required atmospheric oxygen for maximum nitrogenase activity. The maximum specific nitrogenase activities (expressed as micromoles of C
2
H
4
· milligram of bacterial protein
−1
· hour
−1
) noted during the exponential growth phase of the bacteria were the following: 2.68 with
Azospirillum lipoferum
on malate, 2.41 with
K. pneumoniae
and 1.58 with
E. agglomerans
on sucrose, and 0.95 with
Pseudomonas
sp. on malate.
Dissolution and Degradation of
Bacillus thuringiensis
δ-Endotoxin by Gut Juice Protease of the Silkworm
Bombyx mori
Authors: Tojo Akihiko , Aizawa Keio
Published: January 2020

The dissolution and degradation of †-endotoxin (crystal) of
Bacillus thuringiensis
subsp.
kurstaki
strain HD-1 were investigated. Crystals were dissolved in 0.1 M phosphate-carbonate-NaOH buffer at pH > 12. Swelling of crystals occurred in the buffer between pH 10 and 11, and crystals dissolved in the same buffer supplemented with gut juice protease of the silkworm
Bombyx mori.
The proteolytic dissolution of crystals occurred after a time lag of several minutes in 0.1 M carbonate-NaOH buffer, pH 10.2. The time lag was not observed when crystals were suspended in the buffer for 30 min before the addition of protease. After the dissolution of the crystals and further degradation of the solubilized protein, the appearance of a toxic protein with a molecular weight of 59,000, designated P-59, was observed. Lower-molecular-weight peptides (less than 40,000) showed no toxicity to the silkworm larvae on feeding. Digestion of the 120,000-dalton subunit of the crystal by gut juice protease also produced P-59. These observations suggest the occurrence of a similar process in vivo, i.e., the swelling of crystals due to the alkalinity of gut juice and the production of P-59, dependent on the hydrolysis of swollen crystals by gut juice protease.
Lipid-Enhanced Ethanol Production by
Kluyveromyces fragilis
Authors: Janssens Jacques H. , Burris Neil , Woodward Anne , Bailey Richard B.
Published: January 2020

The fermentation ability of a strain of
Kluyveromyces fragilis
, already selected for rapid lactose-fermenting capability, was improved dramatically by the addition of unsaturated fatty acids and ergosterol to the medium. The fermentation time of a 20% whey-lactose medium was decreased from over 90 h to less than 60 h. The lipids were shown to be taken up by the organism, and the effects on specific growth rate and biomass production were determined.
Isolation and Characterization of a Methylotrophic Marine Methanogen,
Methanococcoides methylutens
gen. nov., sp. nov
Authors: Sowers Kevin R. , Ferry James G.
Published: January 2020

A new genus of marine methanogenic bacteria is described that utilizes trimethylamine, diethylamine, monomethylamine, and methanol as substrates for growth and methanogenesis. Methane was not produced from H
2
-CO
2
, sodium formate, or sodium acetate. Growth on trimethylamine was stimulated by yeast extract, Trypticase (BBL Microbiology Systems, Cockeysville, Md.), rumen fluid, or B vitamins. The optimal growth temperature was 30 to 35°C. The maximum growth rate was between pH 7.0 and 7.5. Na
+
(0.4 M) and MgSO
4
(0.05 M) were required for maximum growth. Colonies of the type strain, TMA-10, were yellow, circular, and convex with entire edges. Cells were nonmotile, nonsporeforming, irregular cocci 1 μm in diameter which stained gram negative and occurred singly or in pairs. Micrographs of thin sections revealed a monolayered cell wall approximately 10-nm thick which consisted of protein. Cells were lysed in 0.01% sodium dodecyl sulfate or 0.001% Triton X-100. The DNA base composition was 42 mol% guanine plus cytosine.
Methanococcoides
is the proposed genus and
Methanococcoides methylutens
is the type species. TMA-10 is the type strain (ATCC 33938).
Replica Plating Method for Estimating Phenanthrene-Utilizing and Phenanthrene-Cometabolizing Microorganisms
Authors: Shiaris Michael P. , Cooney Joseph J.
Published: January 2020

A replica plating method was developed for detecting and enumerating phenanthrene-degrading microorganisms. The method is designed to discriminate between aquatic organisms that utilize phenanthrene as the sole carbon and energy source and organisms that cometabolize phenanthrene. The method was used to demonstrate that phenanthrene utilizers and phenanthrene cometabolizers coexist in estuarine sediments.
Adaptation of
Rhodopseudomonas sphaeroides
to Growth on
d
-(—)-Tartrate and Large-Scale Production of a Constitutive
d
-(—)-Tartrate Dehydratase During Growth on
dl
-Malate
Authors: Rode Hergo , Giffhorn Friedrich
Published: January 2020

Of 10 strains of the purple non-sulfur bacterium
Rhodopseudomonas sphaeroides
, 8 acquired the ability to grow on
d
-(—)-tartrate; however, growth occurred only after extended lag phases ranging from 2 to 14 days. These lag phases occurred because only a small number of inoculum cells were able to grow by forming the enzyme
d
-(—)-tartrate dehydratase [
d
-(—)-tartrate hydro-lyase; EC number not yet available]. Once cells had grown on
d
-(—)-tartrate,
d
-(—)-tartrate dehydratase was formed constitutively. Therefore, mass cultivation of
R. sphaeroides
for production of large quantities of enzyme was possible on substrates much cheaper than
d
-(—)-tartrate. When 0.38 mol of
dl
-malate was used as a substrate in a chemotrophic fed-batch culture, a final biomass of 15 g (dry weight) liter
−1
and 1,500 U of
d
-(—)-tartrate dehydratase liter of culture
−1
were formed. The enzyme can be used for selective cleavage of racemic tartaric acid and for quantitative determination of
d
-(—)-tartrate.
Comparison of the Limulus amoebocyte lysate test with plate counts and chemical analyses for assessment of the quality of lean fish
Authors: Sullivan J D , Ellis P C , Lee R G , Combs W S , Watson S W
Published: January 2020

The quality of lean fish was assessed simply and rapidly with Limulus amoebocyte lysate. The endotoxin levels agreed with aerobic plate counts and chemical indices of spoilage. Correlation between level of endotoxin and level of total volatile bases was found to be highly significant (r = 0.8579; P less than 0.001).
Fecal coliforms on environmental surfaces in two day care centers
Authors: Weniger B G , Ruttenber A J , Goodman R A , Juranek D D , Wahlquist S P , Smith J D
Published: January 2020

A survey of environmental surfaces in two Atlanta area day care centers was conducted to determine the prevalence of fecal coliform bacteria, considered a marker for the presence of fecal contamination which might contain pathogenic parasites, bacteria, or viruses. Fecal coliforms were found in 17 (4.3%) of 398 representative samples of building surfaces, furniture, and other objects. These surfaces may be involved in the chain of transmission of enteric diseases among children. Therefore, disinfection of inanimate objects, in addition to good handwashing, may be important in controlling the spread of enteric diseases in day care centers.