bluuebunny/crossref_metadata_2025 huggingface dataset:
Fermentation of peptides and amino acids by a monensin-sensitive ruminal Peptostreptococcus
Authors: Chen G J , Russell J B
Published: January 2020

A monensin-sensitive ruminal peptostreptococcus was able to grow rapidly (growth rate of 0.5/h) on an enzymatic hydrolysate of casein, but less than 23% of the amino acid nitrogen was ever utilized. When an acid hydrolysate was substituted for the enzymatic digest, more than 31% of the nitrogen was converted to ammonia and cell protein. Coculture experiments and synergisms with peptide-degrading strains of Bacteroides ruminicola and Streptococcus bovis indicated that the peptostreptococcus was unable to transport certain peptides or hydrolyze them extracellularly. Leucine, serine, phenylalanine, threonine, and glutamine were deaminated at rates of 349, 258, 102, 95, and 91 nmol/mg of protein per min, respectively. Deamination rates for some other amino acids were increased when the amino acids were provided as pairs of oxidized and reduced amino acids (Stickland reactions), but these rates were still less than 80 nmol/mg of protein per min. In continuous culture (dilution rate of 0.1/h), bacterial dry matter and ammonia production decreased dramatically at a pH of less than 6.0. When dilution rates were increased from 0.08 to 0.32/h (pH 7.0), ammonia production increased while production of bacterial dry matter and protein decreased. These rather peculiar kinetics resulted in a slightly negative estimate of maintenance energy and could not be explained by a change in fermentation products. Approximately 80% of the cell dry matter was protein. When corrections were made for cell composition, the yield of ATP was higher than the theoretical maximum value. It is possible that mechanisms other than substrate-level phosphorylation contributed to the energetics of growth.
Use of a three-stage continuous culture system to study the effect of mucin on dissimilatory sulfate reduction and methanogenesis by mixed populations of human gut bacteria
Authors: Gibson G R , Cummings J H , Macfarlane G T
Published: January 2020

A mixed culture of human fecal bacteria was grown for 120 days in a three-stage continuous culture system. To reproduce some of the nutritional and pH characteristics of the large gut, each vessel had a different operating volume (0.3, 0.5, and 0.8 liter) and pH (6.0, 6.5, and 7.0). A mixture of polysaccharides and proteins was used as carbon and nitrogen sources. Measurements of H2, CH4, S2-, sulfate reduction rates, sulfate-reducing bacteria (SRB), and volatile fatty acids were made throughout the experiment. After 48 days of running, porcine gastric mucin (5.8 g/day) was independently fed to vessel 1 of the multichamber system. The mucin was extensively degraded as evidenced by the stimulation of volatile fatty acid production. In the absence of mucin, sulfate-reducing activity was comparatively insignificant and methanogenesis was the major route for the disposal of electrons. The reverse occurred upon the addition of mucin; sulfate reduction predominated and methanogenesis was completely inhibited. This was attributed to release of sulfate from the mucin which enabled SRB to outcompete methanogenic bacteria for H2. SRB stimulated by mucin were acetate-utilizing Desulfobacter spp., lactate- and H2-utilizing Desulfovibrio spp., and propionate-utilizing Desulfobulbus spp. When the mucin pump was switched off, the multichamber system reverted to a state close to its original equilibrium. These data provide further evidence that sulfated polysaccharides such as mucin may be a source of sulfate for SRB in the human large gut.
Novel method for studying plasmid transfer in undisturbed river epilithon
Authors: Bale M J , Day M J , Fry J C
Published: January 2020

A method for in situ mating experiments is described which involved overnight incorporation of donors containing the mercury resistance plasmid pQM1 and recipients into the epilithon on separate river stones. The stones were then joined to begin the mating. Transfer frequencies obtained were between 2.2 x 10(-1) and 2.5 x 10(-6) per recipient and appeared to depend on the donor-to-recipient ratio (489/1 to 0.0047/1) and not on the river temperature (12 to 19 degrees C). Controls showed that the low density of donors and recipients at the end of the experiment (3.4 x 10(2) to 7.0 x 10(5) cm-2) did not significantly affect the heterotrophic bacterial count (1.43 x 10(6) to 6.39 x 10(6) cm-2) nor the fluorescent-pseudomonad count (2.3 x 10(4) to 9.33 x 10(4) cm-2).
R plasmids in environmental Vibrio cholerae non-O1 strains
Authors: Amaro C , Aznar R , Garay E , Alcaide E
Published: January 2020

The occurrence of drug resistance and its plasmid-mediated transferability was investigated in 140 environmental strains of Vibrio cholerae non-O1 and 6 strains of Vibrio cholerae, both O1 and non-O1, of clinical origin. Of the 146 strains tested, 93% were resistant to at least one drug and 74% were resistant to two or more antibiotics. The O1 strains were susceptible to all antibiotics used. A total of 26 of 28 selected resistant wild strains carried R plasmids that were transferable by intraspecific and intergeneric matings. The most common transmissible R factor determined resistance to ampicillin, amoxicillin, and sulfanilamide (30%), followed by resistance to ampicillin and amoxicillin (13%) and resistance to ampicillin, amoxicillin, phosphomycin, and sulfanilamide (9%). Comparison of the three methods of plasmid analysis showed that the method of Birnboim and Doly (Nucleic Acids Res. 7:1513-1523, 1979) without EDTA and lysozyme was optimal for isolation of both large and small plasmids in environmental V. cholerae strains. Most strains harbored more than one plasmid, and the molecular sizes ranged from 1.1 to 74.8 megadaltons. The plasmids of high molecular size (around 74 megadaltons) were responsible for the resistance pattern transferred and were maintained with high stability in the hosts.
Evaluation of several selective media for recovery of Aeromonas hydrophila from polluted waters
Authors: Arcos M L , de Vicente A , Moriñigo M A , Romero P , Borrego J J
Published: January 2020

Eleven media were studied for their suitability in the selective isolation of Aeromonas hydrophila. Preliminary results showed that five of them (inositol-brilliant green-bile salts agar, bile salts-brilliant green agar, Rimler-Shotts agar, xylose-sodium deoxycholate-citrate agar, and dextrin-fuchsin-sulfite agar) allowed the growth of several microorganisms that are usually present in the same samples in which A. hydrophila is found. Six media (mA agar, modified Rimler-Shotts agar, DNase-toluidine blue-ampicillin agar, Pril-xylose-ampicillin agar, MacConkey-trehalose agar, and starch-bile salts agar) were selected for evaluation as recovery selective media on the basis of their efficiency in the isolation of A. hydrophila from natural water samples. mA agar showed the best recovery rate and also an acceptable specificity, but its selectivity was low. Another medium that can be considered is DNase-toluidine blue-ampicillin agar, which showed good accuracy, but its specificity was low.
Characterization of an Extracellular Protease from the Insect Pathogen
Xenorhabdus luminescens
Authors: Schmidt Thomas M. , Bleakley Bruce , Nealson Kenneth H.
Published: January 2020

Xenorhabdus luminescens
Hm cultured in gelatin broth produced a single extracellular protease. The protease was purified by a factor of 500 and characterized as a monomeric protein with an approximate molecular weight of 61,000. On the basis of inhibitor studies and its pH optimum, the protease was classified as an alkaline metalloprotease with a pH optimum near 8; the isoelectric point of the enzyme is 4.2 ± 0.2. The protease may be a major factor in the ecology of
X. luminescens
, which is carried as a symbiom of some parasitic nematodes.
Properties of the Cell Walls of
Lactococcus lactis
subsp.
cremoris
SK110 and SK112 and Their Relation to Bacteriophage Resistance
Authors: Sijtsma Lolke , Sterkenburg Aart , Wouters Jan T. M.
Published: January 2020

Resistance of
Lactococcus lactis
subsp.
cremoris
SK110 to bacteriophage sk11G, encoded on the plasmid pSK112, is due to poor phage adsorption. Its phage-sensitive variant SK112, cured of pSK112, adsorbs phages effectively. Incubation of SK112 with concanavalin A remarkably reduced phage adsorption to this strain. This treatment also caused agglutination of SK112 that was not found with SK110, indicating different concanavalin A adsorption characteristics of cell walls of both strains. The differences between the two strains were reduced by a mild alkali treatment of cells. This resulted in a positive agglutination with concanavalin A for both strains and in parallel adsorption of phage sk11G to both. Moreover, isolated cell walls of the two strains were investigated, and both bound phage sk11G. These observations suggest the presence of phage receptor material in SK112 as well as in SK110. SK110 contained a relatively high level of bound galactose when compared with the phage-sensitive SK112. After the mild alkali treatment, however, the galactose content of SK110 was diminished such that it became comparable with that of SK112. It is hypothesized that the alkali treatment liberates a galactose-containing component from the cell wall and causes phage sensitivity in
L. lactis
subsp.
cremoris
SK110.
Simultaneous Nitrification and Denitrification in Aerobic Chemostat Cultures of
Thiosphaera pantotropha
Authors: Robertson Lesley A. , van Niel Ed W. J. , Torremans Rob A. M. , Kuenen J. Gijs
Published: January 2020

Thiosphaera pantotropha
is capable of simultaneous heterotrophic nitrification and aerobic denitrification. Consequently, its nitrification potential could not be judged from nitrite accumulation, but was estimated from complete nitrogen balances. The maximum rate of nitrification obtained during these experiments was 93.9 nmol min
−1
mg of protein
−1
. The nitrification rate could be reduced by the provision of nitrate, nitrite, or thiosulfate to the culture medium. Both nitrification and denitrification increased as the dissolved oxygen concentration fell, until a critical level was reached at approximately 25% of air saturation. At this point, the rate of (aerobic) denitrification was equivalent to the anaerobic rate. At this dissolved oxygen concentration, the combined nitrification and denitrification was such that cultures receiving ammonium as their sole source of nitrogen appeared to become oxygen limited and the nitrification rate fell. It appeared that, under carbon-and energy-limited conditions, a high nitrification rate was correlated with a reduced biomass yield. To facilitate experimental design, a working hypothesis for the mechanism behind nitrification and denitrification by
T. pantotropha
was formulated. This involved the basic assumption that this species has a “bottleneck” in its cytochrome chain to oxygen and that denitrification and nitrification are used to overcome this. The nitrification potential of other heterotrophic nitrifiers has been reconsidered. Several species considered to be “poor” nitrifiers also simultaneously nitrify and denitrify, thus giving a falsely low nitrification potential.
Comparison of rapid NFT and API 20E with conventional methods for identification of gram-negative nonfermentative bacilli from pharmaceuticals and cosmetics
Authors: Palmieri M J , Carito S L , Meyer R F
Published: January 2020

The accuracy of the Rapid NFT and the API 20E identification systems was evaluated by comparing them with conventional biochemical methods for the identification of gram-negative, nonfermentative bacilli. The organisms were recovered from preserved, nonsterile pharmaceutical and cosmetic products. A total of 123 test isolates that are commonly encountered in these products were used. By using the criteria of accurate and reliable identification without employing additional tests, Rapid NFT was found to be more accurate after 48 h of incubation than API 20E for characterizing isolates to the species level. Therefore, close agreement between NFT and conventional methods for identification of industrial gram-negative isolates provides evidence that the Rapid NFT system is an improved and rapid method for identifying these organisms to the species level with minimal use of supplementary tests.
Comparative mycobactericidal efficacy of chemical disinfectants in suspension and carrier tests
Authors: Best M , Sattar S A , Springthorpe V S , Kennedy M E
Published: January 2020

The efficacy of nine disinfectants on Mycobacterium smegmatis was tested in the presence of sputum, using quantitative suspension and carrier tests. Glutaraldehyde, povidone iodine, and chlorhexidine gluconate produced at least a 6-log10 reduction in CFU in all tests. Four disinfectants (sodium dichloroisocyanurate, phenol, ethanol, and sodium hypochlorite) were not as effective in the carrier tests as in the suspension tests; this difference ranged from a 1- to a 5-log10 reduction in CFU. The efficacy of ethanol and sodium hypochlorite was further reduced (3- and 1-log10 reductions in CFU, respectively) in the presence of sputum. The quaternary ammonium compound and iodophor were ineffective in all tests. The findings of this study demonstrate the need for a quantitative carrier test such as the one presented here.
Effects of Light and CO on the Survival of a Marine Ammonium-Oxidizing Bacterium during Energy Source Deprivation
Authors: Johnstone Brian H. , Jones Ronald D.
Published: January 2020

The chemolithotrophic ammonium-oxidizing bacterium
Nitrosomonas cryotolerans
responds uniquely to nutrient deprivation by lowering its endogenous respiration and anabolic processes to undetectable levels during starvation, thus appearing to enter a dormant state. To ascertain whether this state protects the cells from further stresses (as seen with endospore-forming bacteria), the starved cells were subjected to two known inhibitors, CO and light. It was found that long-term-starved cells were less resistant than freshly starved cells to light inhibition. Both long-term-starved cells and freshly starved cells were unaffected by CO.
Recovery of DNA from soils and sediments
Authors: Steffan R J , Goksøyr J , Bej A K , Atlas R M
Published: January 2020

Experiments were performed to evaluate the effectiveness of two different methodological approaches for recovering DNA from soil and sediment bacterial communities: cell extraction followed by lysis and DNA recovery (cell extraction method) versus direct cell lysis and alkaline extraction to recover DNA (direct lysis method). Efficiency of DNA recovery by each method was determined by spectrophotometric absorbance and using a tritiated thymidine tracer. With both procedures, the use of polyvinylpolypyrrolidone was important for the removal of humic compounds to improve the purity of the recovered DNA; without extensive purification, various restriction enzymes failed to cut added target DNA. Milligram quantities of high-purity DNA were recovered from 100-g samples of both soils and sediments by the direct lysis method, which was a greater than 1-order-of-magnitude-higher yield than by the cell extraction method. The ratio of labeled thymidine to total DNA, however, was higher in the DNA recovered by the cell extraction method. than by the direct lysis method, suggesting that the DNA recovered by the cell extraction method came primarily from active bacterial cells, whereas that recovered by the direct lysis method may have contained DNA from other sources.
Formation of Polyesters by
Pseudomonas oleovorans
: Effect of Substrates on Formation and Composition of Poly-(
R
)-3-Hydroxyalkanoates and Poly-(
R
)-3-Hydroxyalkenoates
Authors: Lageveen Roland G. , Huisman Gjalt W. , Preusting Hans , Ketelaar Peter , Eggink Gerrit , Witholt Bernard
Published: January 2020

Pseudomonas oleovorans
grows on C
6
to C
12
n
-alkanes and 1-alkenes. These substrates are oxidized to the corresponding fatty acids, which are oxidized further via the β-oxidation pathway, yielding shorter fatty acids which have lost one or more C
2
units.
P. oleovorans
normally utilizes β-oxidation pathway intermediates for growth, but in this paper we show that the intermediate 3-hydroxy fatty acids can also be polymerized to intracellular poly-(
R
)-3-hydroxyalkanoates (PHAs) when the medium contains limiting amounts of essential elements, such as nitrogen. The monomer composition of these polyesters is a reflection of the substrates used for growth of
P. oleovorans
. The largest monomer found in PHAs always contained as many C atoms as did the
n
-alkane used as a substrate. Monomers which were shorter by one or more C
2
units were also observed. Thus, for C-even substrates, only C-even monomers were found, the smallest being (
R
)-3-hydroxyhexanoate. For C-odd substrates, only C-odd monomers were found, with (
R
)-3-hydroxyheptanoate as the smallest monomer. 1-Alkenes were also incorporated into PHAs, albeit less efficiently and with lower yields than
n
-alkanes. These PHAs contained both saturated and unsaturated monomers, apparently because the 1-alkene substrates could be oxidized to carboxylic acids at either the saturated or the unsaturated ends. Up to 55% of the PHA monomers contained terminal double bonds when
P. oleovorans
was grown on 1-alkenes. The degree of unsaturation of PHAs could be modulated by varying the ratio of alkenes to alkanes in the growth medium. Since 1-alkenes were also shortened before being polymerized, as was the case for
n
-alkanes, copolymers which varied with respect to both monomer chain length and the percentage of terminal double bonds were formed during nitrogen-limited growth of
P. oleovorans
on 1-alkenes. Such polymers are expected to be useful for future chemical modifications.
Rapid and simple method for double staining of bacteria with 4',6-diamidino-2-phenylindole and fluorescein isothiocyanate-labeled antibodies
Authors: Hoff K A
Published: January 2020

Bacteria were either heat fixed on microscope slides or filtered with 0.2 micron-pore-size Nuclepore filters. The samples were stained with 4',6-diamidino-2-phenylindole (DAPI) for total staining and with polyvalent rabbit antibodies and fluorescein isothiocyanate-conjugated swine anti-rabbit antibodies for specific staining. By switching between two different optical filter packages in the microscope, only one sample was needed for determining both total and specific counts of bacteria. False-positive counts and other artifacts that occur with antibody staining were easily distinguished when individual fluorescent particles were checked for DAPI fluorescence. The method for applying the general stain to membrane filters was performed quickly and simply by using a DAPI-soaked polypropylene filter that lay beneath the Nuclepore filter which collected the sample.
Presence of an Unusual Methanogenic Bacterium in Coal Gasification Waste
Authors: Tomei Francisco A. , Rouse Dwight , Maki James S. , Mitchell Ralph
Published: January 2020

Methanogenic bacteria growing on a pilot-scale, anaerobic filter processing coal gasification waste were enriched in a mineral salts medium containing hydrogen and acetate as potential energy sources. Transfer of the enrichments to methanol medium resulted in the initial growth of a strain of
Methanosarcina barkeri,
but eventually small cocci became dominant. The cocci growing on methanol produced methane and exhibited the typical fluorescence of methanogenic bacteria. They grew in the presence of the cell wall synthesis-inhibiting antibiotics
d
-cycloserine, fosfomycin, penicillin G, and vancomycin as well as in the presence of kanamycin, an inhibitor of protein synthesis in eubacteria. The optimal growth temperature was 37°C, and the doubling time was 7.5 h. The strain lysed after reaching stationary phase. The bacterium grew poorly with hydrogen as the energy source and failed to grow on acetate. Morphologically, the coccus shared similarities with
Methanosarcina
sp. Cells were 1 μm wide, exhibited the typical thick cell wall and cross-wall formation, and formed tetrads. Packets and cysts were not formed.
Effects of the ionophores monensin and tetronasin on simulated development of ruminal lactic acidosis in vitro
Authors: Newbold C J , Wallace R J
Published: January 2020

A continuous coculture of four ruminal bacteria, Megasphaera elsdenii, Selenomonas ruminantium, Streptococcus bovis, and Lactobacillus sp. strain LB17, was used to study the effects of the ionophores monensin and tetronasin on the changes in ruminal microbial ecology that occur during the onset of lactic acidosis. In control incubations, the system simulated the development of lactic acidosis in vivo, with an initial overgrowth of S. bovis when an excess of glucose was added to the fermentor. Lactobacillus sp. strain LB17 subsequently became dominant as pH fell and lactate concentration rose. Both ionophores were able to prevent the accumulation of lactic acid and maintain a healthy non-lactate-producing bacterial population when added at the same time as an excess of glucose. Tetronasin was more potent in this respect than monensin. When tetronasin was added to the culture 24 h after glucose, the proliferation of lactobacilli was reversed and a non-lactate-producing bacterial population developed, with an associated drop in lactate concentration in the fermentor. Rises in culture pH and volatile fatty acid concentrations accompanied these changes. Monensin was unable to suppress the growth of lactobacilli; therefore, in contrast to tetronasin, monensin added 24 h after the addition of glucose failed to reverse the acidosis. Numbers of lactobacilli and lactate concentrations remained high, whereas pH and volatile fatty acid concentrations were low.
Three dehalogenases and physiological restraints in the biodegradation of haloalkanes by Arthrobacter sp. strain HA1
Authors: Scholtz R , Messi F , Leisinger T , Cook A M
Published: January 2020

Arthrobacter sp. strain HA1 utilizes 18 C2-to-C8 1-haloalkanes for growth and synthesizes an inducible 1-bromoalkane debrominase of unknown physiological function (R. Scholtz, T. Leisinger, F. Suter, and A.M. Cook, J. Bacteriol. 169:5016-5021, 1987) in addition to an inducible 1-chlorohexane halidohydrolase which dehalogenates some 50 substrates, including alpha, omega-dihaloalkanes. alpha, omega-Dihaloalkanes were utilized by cultures of strain HA1 under certain conditions only. C9 and C8 homologs prevented growth. At suitable concentrations, C7-to-C5 homologs could serve as sole sources of carbon and energy for growth. C4 and C3 homologs could be utilized only in the presence of a second substrate (e.g., butanol), and the C2 homolog was not degraded. Kinetics of growth and substrate utilization indicated that cells of strain HA1 growing in butanol-salts medium could be used to test whether compounds induced the 1-chlorohexane halidohydrolase. No gratuitous induction of synthesis of the enzyme was observed. Many enzyme substrates (e.g., bromobenzene) did not induce synthesis of the enzyme, though the enzyme sequence to degrade the product (phenol) was present. Some inducers (e.g., bromomethane) were enzyme substrates but not growth substrates. In an attempt to find a physiological role for the 1-bromoalkane debrominase, we observed that several long-chain haloaliphatic compounds (greater than C9; e.g., 1-bromohexadecane and 1-chlorohexadecane) were utilized for growth and that induced cells could dehalogenate several 1-haloalkanes (at least C4 to C16). The dehalogenation of the long-chain compounds could not be assayed in the cell extract, so we presume that a third haloalkane dehalogenase was present.(ABSTRACT TRUNCATED AT 250 WORDS)
Pressure and Temperature Effects on Growth and Methane Production of the Extreme Thermophile
Methanococcus jannaschii
Authors: Miller Jay F. , Shah Nilesh N. , Nelson Chad M. , Ludlow Jan M. , Clark Douglas S.
Published: January 2020

The marine archaebacterium
Methanococcus jannaschii
was studied at high temperatures and hyperbaric pressures of helium to investigate the effect of pressure on the behavior of a deep-sea thermophile. Methanogenesis and growth (as measured by protein production) at both 86 and 90°C were accelerated by pressure up to 750 atm (1 atm = 101.29kPa), but growth was not observed above 90°C at either 7.8 or 250 atm. However, growth and methanogenesis were uncoupled above 90°C, and the high-temperature limit for methanogenesis was increased by pressure. Substantial methane formation was evident at 98°C and 250 atm, whereas no methane formation was observed at 94°C and 7.8 atm. In contrast, when argon was substituted for helium as the pressurizing gas at 250 atm, no methane was produced at 86°C. Methanogenesis was also suppressed at 86°C and 250 atm when the culture was pressurized with a 4:1 mix of H
2
and CO
2
, although limited methanogenesis did occur when the culture was pressurized with H
2
.
Fast Kinetics of Fe
2+
Oxidation in Packed-Bed Reactors
Authors: Grishin Sergei I. , Tuovinen Olli H.
Published: January 2020

Thiobacillus ferrooxidans
was used in fixed-film bioreactors to oxidize ferrous sulfate to ferric sulfate. Glass beads, ion-exchange resin, and activated-carbon particles were tested as support matrix materials. Activated carbon was tested in both a packed-bed bioreactor and a fluidized-bed bioreactor; the other matrix materials were used in packed-bed reactors. Activated carbon displayed the most suitable characteristics for use as a support matrix of
T. ferrooxidans
fixed-film formation. The reactors were operated within a pH range of 1.35 to 1.5, which effectively reduced the amount of ferric iron precipitation and eliminated diffusion control of mass transfer due to precipitation. The activated-carbon packed-bed reactor displayed the most favorable biomass holdup and kinetic performance related to ferrous sulfate oxidation. The fastest kinetic performance achieved with the activated-carbon packed-bed bioreactor was 78 g of Fe
2+
oxidized per liter per h (1,400 mmol of Fe
2+
oxidized per liter per h) at a true dilution rate of 40/h, which represents a hydraulic retention time of 1.5 min.
Quantitative Assessment of Factors Affecting the Recovery of Indigenous and Released Thermophilic Bacteria from Compost
Authors: Amner Wendy , McCarthy Alan J. , Edwards Clive
Published: January 2020

Thermophilic actinomycetes and bacilli were recovered from mushroom compost by conventional dilution plating and sedimentation chamber-Andersen sampler methods. Excessive growth of thermophilic bacilli on dilution plates accounted for the poor recovery and limited diversity of actinomycete colonies, and this result was largely unaffected by the use of modified extraction procedures and diluents. Assessment of the actinomycete population was more successfully achieved by applying the sedimentation chamber method, by using selective media, or both. Background resistance of the compost microflora to selective agents (kanamycin, novobiocin, tetracycline, thiostrepton, and NaCl) was extremely varied, but both actinomycetes and bacilli were particularly sensitive to tetracycline. The selective isolation of
Thermoactinomyces
spp. and
Thermomonospora chromogena
by novobiocin and kanamycin, respectively, was shown to be reproducible, and the use of high concentrations of kanamycin resulted in the isolation of a novel group of unidentified thermophilic actinomycetes. Comparison of nonselective nutrient media demonstrated that the nutrient-rich protoplast regeneration medium R5 was surprisingly efficient for actinomycete recovery. This medium was found to be particularly appropriate for the recovery of
Saccharomonospora viridis
BD125, introduced as spores into both sterile and fresh samples of mushroom compost. This stable pigmented variant of the
S. viridis
strains indigenous to compost was released at concentrations of up to 10
7
spores g of compost
−1
in order to provide information for future experiments on the release and recovery of genetically manipulated strains. The detection limits for this strain were in the region of 10
2
g
−1
from sterilized compost but only 10
5
g
−1
from nonsterile compost. These figures correspond to mean recovery efficiencies of approximately 70% (sterilized compost) and 53% (fresh compost) of viable spores released. Further improvements in the detection and recovery of
S. viridis
strains released into compost should be achieved by the introduction of selectable markers developed from this information on the antibiotic resistance profile of the indigenous compost microflora.
Mineralization of the dibenzothiophene biodegradation products 3-hydroxy-2-formyl benzothiophene and dibenzothiophene sulfone
Authors: Mormile M R , Atlas R M
Published: January 2020

Dibenzothiophene is degraded to 3-hydroxy-2-formyl benzothiophene by various bacteria, including a strain of Pseudomonas putida that also forms dibenzothiophene sulfone via an alternate pathway. By using these end products as substrates, mixed enrichment cultures that could degrade 3-hydroxy-2-formyl benzothiophene and dibenzothiophene sulfone with the formation of CO2 were established.
Effect of dietary carbohydrates on bacterial cholyltaurine hydrolase in poultry intestinal homogenates
Authors: Feighner S D , Dashkevicz M P
Published: January 2020

The bile salt hydrolase activity in intestinal homogenates reflects composite activities of the gastrointestinal microbial consortia. We have proposed that specific transformations of conjugated bile acids by the intestinal microflora result in the production of metabolites which depress the growth of poultry. The influence of dietary carbohydrates on the physical and kinetic properties of cholyltaurine hydrolase activity, one such bile acid-transforming enzyme in gastrointestinal homogenates of young chickens, was characterized by using a sensitive radiochemical assay. Cholyltaurine hydrolase activity in crude extracts of ileal homogenates was increased twofold by 0.25% Triton X-100 and a freeze-thaw cycle. The pH optimum for cholyltaurine hydrolase from ileal homogenates was very broad and reflected the pH range of poultry intestinal contents (i.e., 5.8 to 6.4). The carbohydrate component of the diet did not affect the apparent temperature optimum (41 degrees C) or stability profile, nor did it affect the apparent Km for taurocholic acid hydrolysis (approximately 0.43 mM). The enzymes in intestinal homogenates were active on all taurine-conjugated bile acids tested. The carbohydrate component of the diet did, however, affect the specific activity of cholyltaurine hydrolase in ileal homogenates from chickens. The levels of cholyltaurine hydrolase activity (rye greater than sucrose greater than corn) in homogenates from birds fed the different diets were directly related to the amount of growth depression (rye greater than sucrose greater than corn) associated with feeding these dietary carbohydrates. These data suggest that intestinal levels of cholyltaurine hydrolase are correlated with the amount of carbohydrate-induced growth depression in poultry.
Establishment of Vesicular-Arbuscular Mycorrhizal Fungi and Other Microorganisms on a Beach Replenishment Site in Florida
Authors: Sylvia D. M. , Will M. E.
Published: January 2020

Beach replenishment is a widely used method of controlling coastal erosion. To reduce erosional losses from wind, beach grasses are often planted on the replenishment sands. However, there is little information on the microbial populations in this material that may affect plant establishment and growth. The objectives of this research were to document changes in the populations of vesicular-arbuscular mycorrhizal (VAM) fungi and other soil microorganisms in replenishment materials and to determine whether roots of transplanted beach grasses become colonized by beneficial microbes. The study was conducted over a 2-year period on a replenishment project in northeastern Florida. Three sampling locations were established at 1-km intervals along the beach. Each location consisted of three plots: an established dune, replenishment sand planted with
Uniola paniculata
and
Panicum
sp., and replenishment sand left unplanted. Fungal and bacterial populations increased rapidly in the rhizosphere of beach grasses in the planted plots. However, no bacteria were recovered that could fix significant amounts of N
2
. The VAM fungi established slowly on the transplanted grasses. Even after two growing seasons, levels of root colonization and sporulation were significantly below those found in the established dune. There was a shift in the dominant VAM fungi found in the planted zone with respect to those in the established dunes. The most abundant species recovered from the established dunes were
Glomus deserticola
, followed by
Acaulospora scrobiculata
and
Scutellospora weresubiae.
The VAM fungi that colonized the planted zone most rapidly were
Glomus globiferum
, followed by
G. deserticola
and
Glomus aggregatum.
Reductive Carboxylation of Propionate to Butyrate in Methanogenic Ecosystems
Authors: Tholozan J. L. , Samain E. , Grivet J. P. , Moletta R. , Dubourguier H. C. , Albagnac G.
Published: January 2020

During the batch degradation of sodium propionate by the anaerobic sludge from an industrial digestor, we observed a significant amount of butyrate formation. Varying the initial propionate concentrations did not alter the ratio of maximal butyrate accumulation to initial propionate concentration within a large range. By measuring the decrease in the radioactivity of [1-
14
C]butyrate during propionate degradation, we estimated that about 20% of the propionate was converted to butyrate. Labeled butyrate was formed from [1-
14
C]propionate with the same specific radioactivity, suggesting a possible direct pathway from propionate to butyrate. We confirmed this hypothesis by nuclear magnetic resonance studies with [
13
C]propionate. The results showed that [1-
13
C]-, [2-
13
C]-, and [3-
13
C]propionate were converted to [2-
13
C]-, [3-
13
C]-, and [4-
13
C]butyrate, respectively, demonstrating the direct carboxylation on the carboxyl group of propionate without randomization of the other two carbons. In addition, we observed an exchange reaction between C-2 and C-3 of the propionate, indicating that acetogensis may proceed through a randomizing pathway. The physiological significance and importance of various metabolic pathways involved in propionate degradation are discussed, and an unusual pathway of butyrate synthesis is proposed.
Fate of Listeria monocytogenes in tissues of experimentally infected cattle and in hard salami
Authors: Johnson J L , Doyle M P , Cassens R G , Schoeni J L
Published: January 2020

Muscle, organ, and lymphoid tissues of four Holstein cows experimentally inoculated (intravenously) with Listeria monocytogenes were examined 2, 6, or 54 days postinoculation for the presence of the organism by direct plating and cold enrichment procedures. L. monocytogenes was isolated from 66% of the tissues sampled; 38% of the isolations were attributed to the use of cold enrichment. Isolation of the organism from muscle tissue was possible only with animals inoculated 2 days before slaughter. The fate of L. monocytogenes during the manufacture and storage of fermented hard salami made from this meat also was determined. Three sausage treatments were evaluated: (i) uninoculated control sausage, (ii) "naturally" contaminated sausage (NC) made from meat of an experimentally inoculated cow, and (iii) sausage made from beef inoculated with a laboratory culture of L. monocytogenes (I). Initial Listeria levels in NC and I sausage were 10(3) CFU/g in trial 1 and 10(4) CFU/g in trial 2. Numbers of L. monocytogenes decreased by approximately 1 log10 CFU/g during fermentation and decreased further during drying and refrigerated storage. Small numbers (less than or equal to 20 CFU/g) of L. monocytogenes were present in I and NC sausage at the end of 12 weeks of refrigerated storage; recovery of these organisms generally depended on the use of an enrichment procedure. The results indicate that L. monocytogenes does not multiply during the fermentation and drying processes typical of hard salami manufacture but that survival may occur if the organism is initially present at greater than or equal to 10(3) CFU/g.
Postprandial changes in methanogenic and acidogenic bacteria in the rumens of steers fed high- or low-forage diets once daily
Authors: Leedle J A , Greening R C
Published: January 2020

Four ruminally fistulated Hereford steers (400 kg) were fed two isocaloric diets at 1.5 x maintenance once daily in a repeated measurement crossover experiment. Postprandial changes in hydrogen-oxidizing, carbon dioxide-reducing bacterial groups were monitored. The methanogenic bacterial populations were present at densities of 4 x 10(8) to 8 x 10(8)/g of ruminal contents on either the high- or low-forage diet. Numbers remained constant postprandially on the high-forage diet but showed a distinct rise and fall with the once-daily feeding of the low-forage diet. Presumed hydrogen- and carbon dioxide-utilizing, acid-producing (acidogenic) bacteria were present between 2 x 10(8) and 12 x 10(8)/g of ruminal contents, with the density of the low-forage population being twofold higher than that of the high-forage population. Acidogenic bacteria exhibited similar postprandial changes on both diets, with the predominant shift being associated with the feeding event. This is the first study which documents the postfeeding trends in ruminal methanogenic bacteria on specified, production-level diets. It is also the first study to suggest that other hydrogen-oxidizing, carbon dioxide-reducing bacteria which produce acid instead of methane are present at high population densities in the normally fed adult ruminant.
Inactivation of particle-associated coliforms by chlorine and monochloramine
Authors: Berman D , Rice E W , Hoff J C
Published: January 2020

Sieves and nylon screens were used to separate primary sewage effluent solids into particle fractions of less than 7- or greater than 7-micron size. The efficiency of separation was determined by using a particle counter. Indigenous coliforms associated with the particle fractions were tested for their resistance to chlorine and monochloramine. Coliforms associated with the less than 7-microns fraction were inactivated more rapidly by 0.5 mg of chlorine per liter at 5 degrees C and pH 7 than coliforms associated with the greater than 7-microns fraction. Homogenization of the greater than 7-microns fraction not only resulted in an increase in the number of less than 7-microns particles, but also increased the rate of inactivation to a rate similar to that of the less than 7-microns fraction. With 1 mg of monochloramine per liter at 5 degrees C and pH 7, particle size had no appreciable effect on the rate of inactivation. At pH 8, however, the less than 7-micron fraction was inactivated more rapidly than the greater than 7-micron fraction. The time required for 99% inactivation of the particle fractions with monochloramine at pH 7 or 8 was 20- to 50-fold greater than the time required for the same amount of inactivation with chlorine at pH 7. The results indicate that coliforms associated with sewage effluent particles are inactivated more rapidly with 0.5 mg of chlorine per liter than with 1.0 mg of monochloramine per liter. However, greater than 7-micron particles can have a protective effect against the disinfecting action of chlorine.
Expression in
Escherichia coli
of the
Cellulomonas fimi
Structural Gene for Endoglucanase B
Authors: Owolabi Joshua B. , Beguin Pierre , Kilburn Douglas G. , Miller Robert C. , Warren R. Antony J.
Published: January 2020

Endoglucanase B (EB) of
Cellulomonas fimi
has an
M
r
of 110,000 when it is produced in
Escherichia coli
. The level of expression of the
cenB
gene (encoding EB) was significantly increased by replacing its normal transcriptional and translational regulatory signals with those of the
E. coli lac
operon. EB was purified to homogeneity from the periplasmic fraction of
E. coli
in one step by affinity chromatography on microcrystalline cellulose (Avicel). Alignment of the NH
2
-terminal amino acid sequence with the partial nucleotide sequence of a fragment of
C. fimi
DNA showed that EB is preceded by a putative signal polypeptide of 33 amino acids. The signal peptide functions and is processed correctly in
E. coli
, even when its first 15 amino acids are replaced by the first 7 amino acids of β-galactosidase. The intact EB polypeptide is not required for enzymatic activity. Active polypeptides with
M
r
s of 95,000 and 82,000 also appear in
E. coli
, and a deletion mutant of
cenB
encodes an active polypeptide with an
M
r
of 72,000.
Preparation and Purification of Xylitol-5-Phosphate from a Cell Extract of
Lactobacillus casei
Cl-16
Authors: Trahan L. , Néron S. , Bareil M.
Published: January 2020

A simple procedure which yields pure xylitol-5-phosphate is described. A cell extract of
Lactobacillus casei
Cl-16 from a 6-liter culture was used to synthesize up to 70 mg of xylitol-5-phosphate overnight from xylitol and phosphoenolpyruvate via a xylitol phosphoenolpyruvate:phosphotransferase system with a 53% yield. Centrifugation, filtration, precipitation as a barium salt, and ion-exchange batch chromatography permitted recovery of nearly 90% of the phosphorylated product synthesized. Thin-layer chromatography and enzymatic analysis indicated a purity level of more than 99%. The method was used to synthesize [U-
14
C]xylitol-5-phosphate, and it is suitable for the synthesis of many other nonmetabolizable sugar phosphates.
Widespread occurrence of the restriction endonuclease YenI, an isoschizomer of PstI, in Yersinia enterocolitica serotype O8
Authors: Miyahara M , Maruyama T , Wake A , Mise K
Published: January 2020

The cold-active restriction endonuclease YenI, an isoschizomer of PstI, was found in 12 of 14 Yersinia enterocolitica serotype O8 strains of different origins, but not in other serotypes of Y. enterocolitica, Yersinia pseudotuberculosis, or Yersinia pestis. In spite of the limited number of strains tested, the result suggests that the detection of YenI endonuclease or the gene might result in more rapid determination of the prominently pathogenic serotype of Y. enterocolitica.
Catalase and superoxide dismutase activities after heat injury of Listeria monocytogenes
Authors: Dallmier A W , Martin S E
Published: January 2020

Four strains of Listeria monocytogenes were examined for catalase (CA) and superoxide dismutase (SOD) activities. The two strains having the highest CA activities (LCDC and Scott A) also possessed the highest SOD activities. The CA activity of heated cell extracts of all four strains examined decreased sharply between 55 and 60 degrees C. SOD was more heat labile than CA. Two L. monocytogenes strains demonstrated a decline in SOD activity after heat treatment at 45 degrees C, whereas the other two strains demonstrated a decline at 50 degrees C. Sublethal heating of the cells at 55 degrees C resulted in increased sensitivity to 5.5% NaCl. Exogenous hydrogen peroxide was added to suspensions of L. monocytogenes; strains producing the highest CA levels showed the greatest H2O2 resistance.
Methanogenic bacteria from human dental plaque
Authors: Belay N , Johnson R , Rajagopal B S , de Macario E C , Daniels L
Published: January 2020

Samples of human dental plaque were examined for the presence of methanogenic bacteria. Of 54 samples from 36 patients, 20 yielded H2/CO2-using methanogenic enrichment cultures. All methanogen-positive samples were from patients with some degree of periodontal disease. The predominant populations in the enrichments had morphologies characteristic of Methanobrevibacter spp. In six enrichments derived from three patients, the common methanogen was antigenically similar to Methanobrevibacter smithii. The same was true for the three methanogenic isolates obtained in axenic culture from a fourth patient. The six enrichments and two of the three isolates were antigenically closer to strain ALI than to PS. Two of the enrichments also had subpopulations with weak antigenic similarity to Methanosphaera stadtmanae. The data indicate that methanogens in the oral cavity of humans are antigenically close to those found in the intestinal tract.
Intraspecies genotypic heterogeneity among Mycoplasma gallisepticum strains
Authors: Santha M , Lukacs K , Burg K , Bernath S , Rasko I , Stipkovits L
Published: January 2020

The DNA cleavage patterns and protein profiles of six Mycoplasma gallisepticum strains from various parts of the world were compared. Obvious differences among the strains were obtained by DNA restriction analysis. Reflection of genotypic variations in the polypeptide patterns was less pronounced; slight differences in the protein profiles of the strains were found. The data presented here indicate that some intraspecies polymorphism exists among M. gallisepticum strains.
Factors promoting survival of bacteria in chlorinated water supplies
Authors: LeChevallier M W , Cawthon C D , Lee R G
Published: January 2020

Results of our experiments showed that the attachment of bacteria to surfaces provided the greatest increase in disinfection resistance. Attachment of unencapsulated Klebsiella pneumoniae grown in medium with high levels of nutrients to glass microscope slides afforded the microorganisms as much as a 150-fold increase in disinfection resistance. Other mechanisms which increased disinfection resistance included the age of the biofilm, bacterial encapsulation, and previous growth conditions (e.g., growth medium and growth temperature). These factors increased resistance to chlorine from 2- to 10-fold. The choice of disinfectant residual was shown to influence the type of resistance mechanism observed. Disinfection by free chlorine was affected by surfaces, age of the biofilm, encapsulation, and nutrient effects. Disinfection by monochloramine, however, was only affected by surfaces. Importantly, results showed that these resistance mechanisms were multiplicative (i.e., the resistance provided by one mechanism could be multiplied by the resistance provided by a second mechanism).
Primary and Bacterial Secondary Production in a Southwestern Reservoir
Authors: Chrzanowski Thomas H. , Hubbard James G.
Published: January 2020

Rates of primary and bacterial secondary production in Lake Arlington, Texas, were determined. The lake is a warm (annual temperature range, 7 to 32°C), shallow, monomictic reservoir with limited macrophyte development in the littoral zone. Samples were collected from six depths within the photic zone from a site located over the deepest portion of the lake. Primary production and bacterial production were calculated from NaH
14
CO
3
and [
methyl
-
3
H]thymidine incorporation, respectively. Peak instantaneous production ranged between 14.8 and 220.5 μg of C liter
−1
h
−1
. There were two distinct periods of high rates of production. From May through July, production near the metalimnion exceeded 100 μg of C liter
−1
h
−1
. During holomixis, production throughout the water column was in excess of 100 μg of C liter
−1
h
−1
and above 150 μg of C liter
−1
h
−1
near the surface. Annual areal primary production was 588 g of C m
−2
. Bacterial production was markedly seasonal. Growth rates during late fall through spring were typically around 0.002 h
−1
, and production rates were typically 5 μg of C liter
−1
h
−1
. Growth rates were higher during warmer parts of the year and reached 0.03 h
−1
by August. The maximum instantaneous rate of bacterial production was approximately 45 μg of C liter
−1
h
−1
. Annual areal bacterial production was 125 g of C m
−2
. Temporal and spatial distributions of bacterial numbers and activities coincided with temporal and spatial distributions of primary production. Areal primary and bacterial secondary production were highly correlated (
r
= 0.77,
n
= 15,
P
< 0.002).