Showing papers in "Applied and Environmental Microbiology in 1978"
TL;DR: Initial applications of the present method for hydrobiological purposes showed that the proportion of respiring aquatic bacteria ranged between 6 to 12% (samples taken from coastal areas of the Baltic Sea) and 5 to 36% (sampled taken from freshwater lakes and ponds).
Abstract: The electron transport system of respiring organisms reduces 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to INT-formazan. Respiring bacteria deposit accumulated INT-formazan intracellularly as dark red spots. Corresponding to electron transport system activity, these deposits attain a size and a degree of optical density which allows them to be examined by light microscopy. If polycarbonate filters and epifluorescence microscopy are applied to analyze an INT-treated water sample, it is possible to differentiate between respiring and apparently nonrespiring bacteria. This differentiation, which permits determinations of the total number of bacteria and the proportion thereof involved in respiration, is realized directly within one and the same microscopic image. Initial applications of the present method for hydrobiological purposes showed that the proportion of respiring aquatic bacteria ranged between 6 to 12% (samples taken from coastal areas of the Baltic Sea) and 5 to 36% (samples taken from freshwater lakes and ponds). Cells of 1.6 to 2.4 micrometer (freshwater) and 0.4 micrometer (Baltic Sea) account for the highest proportion of respiring bacteria.
564 citations
TL;DR: A. hydrophila could not be isolated from extremely saline, thermal, or polluted waters, even though it was found over wide ranges of salinity, conductivity, temperature, pH, and turbidity.
Abstract: The abundance of Aeromonas hydrophila was measured in 147 natural aquatic habitats in 30 states and Puerto Rico. Viable cell counts were used to estimate density at all sites by using Rimler-Shotts medium, a differential presumptive medium for A. hydrophila. Temperature, pH, conductivity, salinity, and turbidity were measured simultaneously with water sample collection. The density of A. hydrophila was higher in lotic than in lentic systems. Saline systems had higher densities of A. hydrophila than did freshwater systems. A. hydrophila could not be isolated from extremely saline, thermal, or polluted waters, even though it was found over wide ranges of salinity, conductivity, temperature, pH, and turbidity. Of the water quality parameters measured, only conductivity was significantly regressed with density of A. hydrophila.
377 citations
TL;DR: A method has been developed for measurement of denitrification activity in sediments by application of the acetylene inhibition technique, where acetylene-saturated water was injected into sediment cores which were then incubated for a few hours at the in situ temperature.
Abstract: A method has been developed for measurement of denitrification activity in sediments by application of the acetylene inhibition technique. Acetylene-saturated water was injected, at close intervals, into sediment cores which were then incubated for a few hours at the in situ temperature. Frozen segments of the cores were assayed for accumulation of N2O by a combined gas extraction and detection system. The segments were thawed under a stream of helium from which N2O (and other gases) was collected in a liquid N2 trap, and the quantity of N2O was measured by gas chromatography. The maximum rate of denitrification in a coastal marine sediment was 35 nmol of N per cm3 of sediment per day at 2.5°C, and the rate of denitrification for the total sediment was 0.99 nmol of N per m2 per day.
316 citations
TL;DR: The data suggested that the latter process may be equally as significant as denitrification in the turnover of NO(3) in marine sediments.
Abstract: The capacity for dissimilatory reduction of NO3− to N2 (N2O) and NH4+ was measured in 15NO3−-amended marine sediment. Incubation with acetylene (7 × 10−3 atmospheres [normal]) caused accumulation of N2O in the sediment. The rate of N2O production equaled the rate of N2 production in samples without acetylene. Complete inhibition of the reduction of N2O to N2 suggests that the “acetylene blockage technique” is applicable to assays for denitrification in marine sediments. The capacity for reduction of NO3− by denitrification decreased rapidly with depth in the sediment, whereas the capacity for reduction of NO3− to NH4+ was significant also in deeper layers. The data suggested that the latter process may be equally as significant as denitrification in the turnover of NO3− in marine sediments.
313 citations
TL;DR: It was concluded that acetate splitting rather than "methanogenesis from fatty acids" is the rate-limiting reaction in the anaerobic degradation of dissolved organic matter and that a methoanogenic anaer aerobic ecosystem is stabilized by its large unused capacity of hydrogen consumption which is "buffering" the partial pressure of dissolved hydrogen in the system at sufficiently low values to permit rapid fatty acid oxidation.
Abstract: The kinetics of propionate degradation, acetate splitting, and hydrogen consumption in digesting sludge were investigated in a lab-scale digester. At natural steady-state conditions, the acetate-splitting systems in well-digested sludge were about half saturated. Propionate-degrading systems were saturated to only 10 to 15%, and hydrogen removal was less than 1% of the maximum possible rate. It was concluded that acetate splitting rather than "methanogenesis from fatty acids" is the rate-limiting reaction in the anaerobic degradation of dissolved organic matter and that a methoanogenic anaerobic ecosystem is stabilized by its large unused capacity of hydrogen consumption which is "buffering" the partial pressure of dissolved hydrogen in the system at sufficiently low values to permit rapid fatty acid oxidation. A tentative scheme of the substrate flow in sludge digestion is presented. It suggests that acid formation coupled with hydrogen formation via pyridine dinucleotide oxidation yields the immediate substrates, namely acetate and hydrogen, for about 54% of the total methanogenesis.
297 citations
TL;DR: Methanogenic bacteria can be tentatively identified by fluorescence microscopy by carefully selecting a series ofexcitation and barrier filters that matched the excitation and emission spectra of some unique coenzymes in methanogenic bacteria.
Abstract: Methanogenic bacteria can be tentatively identified by fluorescence microscopy. This technique was improved by carefully selecting a series of excitation and barrier filters that matched the excitation and emission spectra of some unique coenzymes viz., F420 and F350, in methanogenic bacteria.
289 citations
TL;DR: Results suggested that methanogenesis from acetate, methanol, and H(2)-CO(2) may have some steps in common, as originally proposed by Barker.
Abstract: Methanosarcina strain 227 exhibited exponential growth on sodium acetate in the absence of added H2. Under these conditions, rates of methanogenesis were limited by concentrations of acetate below 0.05 M. One mole of methane was formed per mole of acetate consumed. Additional evidence from radioactive labeling studies indicated that sufficient energy for growth was obtained by the decarboxylation of acetate. Diauxic growth and sequential methanogenesis from methanol followed by acetate occurred in the presence of mixtures of methanol and acetate. Detailed studies showed that methanol-grown cells did not metabolize acetate in the presence of methanol, although acetate-grown cells did metabolize methanol and acetate simultaneously before shifting to methanol. Acetate catabolism appeared to be regulated in response to the presence of better metabolizable substrates such as methanol or H2-CO2 by a mechanism resembling catabolite repression. Inhibition of methanogenesis from acetate by 2-bromoethanesulfonate, an analog of coenzyme M, was reversed by addition of coenzyme M. Labeling studies also showed that methanol may lie on the acetate pathway. These results suggested that methanogenesis from acetate, methanol, and H2-CO2 may have some steps in common, as originally proposed by Barker. Studies with various inhibitors, together with molar growth yield data, suggest a role for electron transport mechanisms in energy metabolism during methanogenesis from methanol, acetate, and H2-CO2.
277 citations
TL;DR: Reduction of seven azo dyes was carried out by cell suspensions of predominant intestinal anaerobes and data suggest that an extracellular shuttle is required for azo reduction.
Abstract: Reduction of seven azo dyes (amaranth, Ponceau SX, Allura Red, Sunset Yellow, tartrazine, Orange II, and methyl orange) was carried out by cell suspensions of predominant intestinal anaerobes. It was optimal at pH 7.4 in 0.4 M phosphate buffer and inhibited by glucose. Flavin mononucleotide caused a marked enhancement of azo reduction by Bacteroides thetaiotaomicron. Other electron carriers, e.g., methyl viologen, benzyl viologen, phenosafranin, neutral red, crystal violet, flavin adenine dinucleotide, menadione, and Janus Green B can replace flavin mononucleotide. These data suggest that an extracellular shuttle is required for azo reduction.
268 citations
TL;DR: Five species of rumen bacteria with overlapping substrate fermentative capabilities were tested for substrate preferences and evidence of catabolite regulatory mechanisms, suggesting that the five bacteria have different strategies of substrate utilization and thus occupy separate niches in the rumen.
Abstract: Five species of rumen bacteria with overlapping substrate fermentative capabilities were tested for substrate preferences and evidence of catabolite regulatory mechanisms. All five bacteria showed evidence of some type of catabolite regulatory mechanism. In the six-substrate test system that was used, utilization of every substrate was inhibited by another substrate in at least one of the bacteria. Inhibited versus noninhibited substrate data suggest that the five bacteria have different strategies of substrate utilization and thus occupy separate niches in the rumen. The significance of these observations to understanding the rumen ecosystem is discussed.
267 citations
TL;DR: A replica plating method for rapid quantitation of ice nucleation-active (INA) bacteria was developed and numbers of INA bacteria were large enough to suggest that plant surfaces may constitute a significant source of atmospheric ice nuclei.
Abstract: A replica plating method for rapid quantitation of ice nucleation-active (INA) bacteria was developed. Leaf washings of plant samples from California, Colorado, Florida, Louisiana, and Wisconsin were tested for the presence of INA bacteria. Of the 95 plant species sampled, 74 were found to harbor INA bacteria. Only the conifers were, as a group, unlikely to harbor INA bacteria. All of the INA bacteria isolated resembled either Pseudomonas syringae or Erwinia herbicola. Sufficient numbers of INA bacteria were present on the samples to account for the ice nuclei associated with leaves that are necessary for freezing injury to occur. Numbers of INA bacteria were large enough to suggest that plant surfaces may constitute a significant source of atmospheric ice nuclei.
252 citations
TL;DR: It was shown that purified 14C-labeled milled-wood lignin was attacked, with recoveries of up to 17.7% of the label was 14CO2, the first conclusive evidence to show that streptomycetes can decompose lignIn.
Abstract: From 30 actinomycete cultures isolated by enrichment technique on agar media containing newsprint as a primary carbon and energy source, three Streptomyces strains were selected for characterization of their lignocellulose-decomposing abilities. All three streptomycetes were capable of oxidizing specifically 14C-labeled lignocelluloses to 14CO2. These Streptomyces were shown to attack primarily the cellulosic (glucan) components, of which between 25 to 40% evolved as 14CO2 during 1,025 h of incubation depending upon the culture used. Lignin labeled lignocelluloses were also attacked, but to a lesser degree, with up to about 3.5% being oxidized to 14CO2 depending upon the culture used. Additionally, it was shown that purified 14C-labeled milled-wood lignin was attacked, with recoveries of up to 17.7% of the label was 14CO2. This is the first conclusive evidence to show that streptomycetes can decompose lignin.
TL;DR: The data indicate that four- and five-ring PAH compounds, several of which are carcinogenic, may persist even in sediments that have received chronic PAH inputs and that support microbial populations capable of transforming two- and three-ringPAH compounds.
Abstract: To determine rates of microbial transformation of polycyclic aromatic hydrocarbons (PAH) in freshwater sediments, 14C-labeled PAH were incubated with samples from both pristine and petroleum-contaminated streams. Evolved 14CO2 was trapped in KOH, unaltered PAH and polar metabolic intermediate fractions were quantitated after sediment extraction and column chromatography, and bound cellular 14C was measured in sediment residues. Large fractions of 14C were incorporated into microbial cellular material; therefore, measurement of rates of 14CO2 evolution alone would seriously underestimate transformation rates of [14C]naphthalene and [14C]anthracene. PAH compound turnover times in petroleum-contaminated sediment increased from 7.1 h for naphthalene to 400 h for anthracene, 10,000 h for benz(a)anthracene, and more than 30,000 h for benz(a)pyrene. Turnover times in uncontaminated stream sediment were 10 to 400 times greater than in contaminated samples, while absolute rates of PAH transformation (micrograms of PAH per gram of sediment per hour) were 3,000 to 125,000 times greater in contaminated sediment. The data indicate that four- and five-ring PAH compounds, several of which are carcinogenic, may persist even in sediments that have received chronic PAH inputs and that support microbial populations capable of transforming two- and three-ring PAH compounds.
TL;DR: The reduction rate data suggest that the pathway of nitrate reduction to ammonia is important in coastal sediments.
Abstract: Simultaneous determinations of nitrogen gas production, ammonia, and particulate organic nitrogen formation in the coastal sediments of Mangoku-Ura, Simoda Bay, and Tokyo Bay were made by using the 15N-label tracer method. The rate of nitrogen gas production in the sediment surface layer was about 10−2 μg atom of N per g per h, irrespective of the location of the sediments examined. [15N]ammonia and -particulate organic nitrogen accounted for 20 to 70% of the three products, and after several hours of incubation, the major fraction of nondenitrified 15N in Mangoku-Ura and Simoda Bay sediments was recovered as ammonia. In Tokyo Bay sediments, particulate organic nitrogen was produced at a greater rate than was ammonia. The reduction rate data suggest that the pathway of nitrate reduction to ammonia is important in coastal sediments.
TL;DR: With the increasing significance of group IV atypical mycobacteria as etiological agents in a variety of infections, studies were conducted to determine their growth capabilities in water and their comparative resistance to disinfectants used to decontaminate hospital equipment.
Abstract: With the increasing significance of group IV atypical mycobacteria as etiological agents in a variety of infections, studies were conducted to determine their growth capabilities in water and their comparative resistance to disinfectants used to decontaminate hospital equipment. Isolates of Mycobaterium chelonei (TM strains) from peritoneal fluids of patients and peritoneal dialysis machines were able to multiply in commercial distilled water, with generation times at 25 degrees C ranging from 8 to 15 h. Levels of 10(5) to 10(6) cells per ml were attained, and these stationary-phase populations declined only slightly over a 1-year period. Results of studies to determine resistance to disinfectants showed the following. (i) TM strains of M. chelonei cultured in commercial distilled water showed survivors in 2% aqueous formaldehyde (HCHO) solutions up to 24 h; in 8% HCHO, only a 2-log reduction in viable counts was observed over a 2-h sampling period. Reference ATCC strains of M. chelonei and M. fortuitum were rapidly inactivated, with no survivors after 2 h of exposure to 2% HCHO or 15 min of exposure to 8% HCHO. (ii) In 2% alkaline glutaraldehyde, TM strains survived 60 min. whereas ATCC strains showed no survivors after 2 min of contact time. (iii) All M. chelonei and M. fortuitum strains survived 60 min of exposure to concentrations of 0.3 and 0.7 microgram of free chlorine per ml at pH 7.
TL;DR: An acetate-fermenting strain of Methanosarcina was isolated from an acetate enrichment culture inoculated with anaerobic sludge from a waste treatment digestor and labeling studies indicated that acetate was converted to methane and CO2 as predicted by previous studies on mixed cultures.
Abstract: An acetate-fermenting strain of Methanosarcina was isolated from an acetate enrichment culture inoculated with anaerobic sludge from a waste treatment digestor. In pure culture, this organism fermented acetate in the absence of added hydrogen at rates comparable in magnitude to those found in digestor systems. This rate was significantly higher than previously obtained for pure cultures of this genus. Mineral components of yeast extract were highly stimulatory for cultures growing on methanol. Comparable stimulation was not observed for cultures growing on acetate. Labeling studies indicated that acetate was converted to methane and CO2 as predicted by previous studies on mixed cultures. Total oxidation or reduction of acetate was not the mechanism of conversion of acetate to methane by the pure culture. The ability of this strain to form colonies or to produce methane from acetate was apparently influenced by the choice of substrate and conditions used for growing the inoculum.
TL;DR: The New York Bight observation suggests that genes for Hg resistance and beta-lactamase production are simultaneously selected for in Bacillus and that heavy-metal contamination of an ecosystem can result in a selection pressure for antibiotic resistance in bacteria in that system.
Abstract: The New York Bight extends seaward some 80 to 100 miles (ca. 129 to 161 km) from the Long Island and New Jersey shorelines to the edge of the continental shelf. Over 14 x 10(6) m(3) of sewage sludge, dredge spoils, acid wastes, and cellar dirt are discharged into this area each year. Large populations of Bacillus sp. resistant to 20 mug of mercury per ml were observed in Bight sediments contaminated by these wastes. Resistant Bacillus populations were much greater in sediments containing high concentrations of Hg and other heavy metals than in sediments from areas further offshore where dumping has never been practiced and where heavy-metal concentrations were found to be low. Ampicillin resistance due mainly to beta-lactamase production was significantly (P < 0.001) more frequent in Bacillus strains from sediments near the sewage sludge dump site than in similar Bacillus populations from control sediments. Bacillus strains with combined ampicillin and Hg resistances were almost six times as frequent at the sludge dump site as in control sediments. This observation suggests that genes for Hg resistance and beta-lactamase production are simultaneously selected for in Bacillus and that heavy-metal contamination of an ecosystem can result in a selection pressure for antibiotic resistance in bacteria in that system. Also, Hg resistance was frequently linked with other heavy-metal resistances and, in a substantial proportion of Bacillus strains, involved reduction to volatile metallic Hg (Hg degrees ).
TL;DR: Spearman rank correlation analysis revealed significant interrelationships between the number of active bacteria and the actual uptake rate of glucose in water samples taken immediately above sandy sediments at beaches of the Kiel Fjord and theKiel Bight.
Abstract: A technique is described for the determination of bacterial numbers and the spectrum of actively metabolizing cells on the same microscopic preparation by a combined autoradiography/epifluorescence microscopy technique. Natural bacterial populations incubated with [3H]glucose were filtered onto 0.2-μm Nuclepore polycarbonate membranes. The filters were cut into quarters and fixed on the surface of glass slides, coated with NTB-2 nuclear track emulsion (Kodak), and exposed to the radiation. After processing, the autoradiographs were stained with acridine orange. A combination of overstaining on the slightly alkaline side and gradual destaining on the acid side of neutrality gave the best results. Epifluorescence microscopy revealed bright-orange fluorescent cells with dark-silver grains associated against a greenish-to-grayish background. Based on the standardization curves, detection of actually metabolizing cells was optimal when cells were incubated with 1 to 5 μCi of [3H]glucose per ml of sample for 4 h and the autoradiographs were exposed to NTB-2 emulsion at 7°C for 3 days. In water samples taken immediately above sandy sediments at beaches of the Kiel Fjord and the Kiel Bight (Baltic Sea, FRG), between 2.3 and 56.2% (average, 31.3%) of the total number of bacteria were actually metabolizing cells. Spearman rank correlation analysis revealed significant interrelationships between the number of active bacteria and the actual uptake rate of glucose.
TL;DR: A general reduction of metabolic rate at extreme salinities is strongly suggested and raises doubt about the biodegradation of hydrocarbons in hypersaline environments.
Abstract: When mineral oil, hexadecane, and glutamate were added to natural samples of varying salinity (3.3 to 28.4%) from salt evaporation ponds and Great Salt Lake, Utah, rates of metabolism of these compounds decreased as salinity increased. Rate limitations did not appear to relate to low oxygen levels or to the availability of organic nutrients. Some oxidation of l-[U-14C]glutamic acid occurred even at extreme salinities, whereas oxidation of [1-14C]hexadecane was too low to be detected. Gas chromatographic examination of hexane-soluble components of tar samples from natural seeps at Rozel Point in Great Salt Lake demonstrated no evidence of biological oxidation of isoprenoid alkanes subject to degradation in normal environments. Some hexane-soluble components of the same tar were altered by incubation in a low-salinity enrichment culture inoculated with garden soil. Attempts to enrich for microorganisms in saline waters able to use mineral oil as a sole source of carbon and energy were successful below, but not above, about 20% salinity. This study strongly suggests a general reduction of metabolic rate at extreme salinities and raises doubt about the biodegradation of hydrocarbons in hypersaline environments.
TL;DR: The temperature optimum for photosynthesis of natural populations of blue-green algae (cyanobacteria) from Lake Mendota was determined during the period of June to November 1976 and photosynthesis appears to be a valid index of growth.
Abstract: The temperature optimum for photosynthesis of natural populations of blue-green algae (cyanobacteria) from Lake Mendota was determined during the period of June to November 1976. In the spring, when temperatures ranged from 0 to 20°C, there were insignificant amounts of blue-green algae in the lake (less than 1% of the biomass). During the summer and fall, when the dominant phytoplankton was blue-green algae, the optimum temperature for photosynthesis was usually between 20 and 30°C, whereas the environmental temperatures during this period ranged from 24°C in August to 12°C in November. In general, the optimum temperature for photosynthesis was higher than the environmental temperature. More importantly, significant photosynthesis also occurred at low temperature in these samples, which suggests that the low temperature alone is not responsible for the absence of blue-green algae in Lake Mendota during the spring. Temperature optima for growth and photosynthesis of laboratory cultures of the three dominant blue-green algae in Lake Mendota were determined. The responses of the two parameters to changes in temperature were similar; thus, photosynthesis appears to be a valid index of growth. However, there was little photosynthesis by laboratory cultures at low temperatures, in contrast to the natural samples. Evidence for an interaction between temperature and low light intensities in their effect on photosynthesis of natural samples is presented.
TL;DR: It was concluded that treatment with ethanol for 1 h is an effective technique for selective isolation of sporeforming bacteria from mixed cultures and certain types of clinical specimens.
Abstract: When mixed cultures containing sporeforming bacteria were treated with heat or with ethanol, the latter consistently resulted in better recovery of Clostridium and Bacillus species. Both techniques were effective in eliminating vegetative cells. An ethanol concentration greater than 25% and exposure for 45 min or longer were necessary to kill all vegetative cells in mixed-culture samples. Ethanol treatment (50% ethanol for 1 h) was effective for isolating sporeforming bacteria from intestinal specimens. Seven different species of Clostridium were the only bacteria isolated from the ethanol-treated specimen of intestinal contents from the large bowel of a patient. It was concluded that treatment with ethanol for 1 h is an effective technique for selective isolation of sporeforming bacteria from mixed cultures and certain types of clinical specimens.
TL;DR: The presence of pigmented microbial forms leads us to believe that natural selection is occurring in the mesosphere because cells possessing chromogenous pigments (carotenoids, melanins) are more resistant to ultraviolet-ray action.
Abstract: By using meterological rockets fitted with specially designed analyzers, samples for microbiological investigation have been taken. The analyzer design prevented extraneous microorganisms from penetrating into the analyzer. Before being used, the analyzers were sterilized with high gamma-ray doses. For the first time microorganisms have been detected in the mesosphere at an altitude of 48 to 77 km. The microorganisms are microscopic fungi having black conidia or spores (Circinella muscae, Aspergillus niger, Papulaspora anomala) and one species forming green conidia (Penicillium notatum). Colonies of Mycobacterium luteum and Micrococcus albus have also grown. Five of the six species have synthesized pigments. The presence of pigmented microbial forms leads us to believe that natural selection is occurring in the mesosphere because cells possessing chromogenous pigments (carotenoids, melanins) are more resistant to ultraviolet-ray action. A greater number of microorganisms have been registered in the mesosphere during dust storms than in the absence of strong winds. Images
TL;DR: These studies show that the propionibacteria are ubiquitous on the skin, with P. acnes predominant in both prevalence and population, especially in areas rich in sebum.
Abstract: Propionibacterium acnes, P. avidum, and P. granulosum were quantitatively measured in 50 young adults. The scalp, forehead, external auditory canal, alae nasi, anterior nares, groin, rectum, and antecubital and popliteal fossa were sampled. These represent various cutaneous microenvironments, differing in moisture, density of sweat, sebaceous glands, and extent of anaerobiosis. These studies show that the propionibacteria are ubiquitous on the skin, with P. acnes predominant in both prevalence and population, especially in areas rich in sebum. P. granulosum recovery paralled that of P. acnes, but the density was significantly lower. P. avidum was found mainly in moist areas and the retum, suggesting an intestinal reservoir.
TL;DR: Thirty-one isomers of polychlorinated biphenyl (PCB) were examined for biodegradability by two species of Alcaligenes and Acinetobacter and significant differences between the two organisms with respect to degradability were not observed except for 2,4,6-trichlorobiphenyl.
Abstract: Thirty-one isomers of polychlorinated biphenyl (PCB) were examined for biodegradability by two species of Alcaligenes and Acinetobacter. The following relationships between chlorine substitution and biodegradability of PCBs were observed. (i) Degradation decreased as chlorine substitution increased. PCB isomers containing more than four chlorines were less susceptible to degradation. (ii) PCBs containing two chlorines on either the ortho position of a single ring (i.e., 2,6-) or on both rings (i.e., 2,2′-) showed very poor degradability. (iii) PCBs containing all chlorine atoms on only a single ring were generally degraded faster than when the same number of chlorines were substituted on both rings. (iv) Preferential ring fission of the molecules occurred with nonchlorinated or lesser chlorinated rings. (v) The formation and accumulation of a yellow intermediate was always observed in 4′-chloro-substituted PCBs. (vi) Significant differences between the two organisms with respect to degradability were not observed except for 2,4,6-trichlorobiphenyl.
TL;DR: Net production of isobutyric acid, isovaleric acid, and 2-methylbutyric Acid by cultures of Bacteroides ruminicola and Megasphaera elsdenii on media that contained Trypticase or casein hydrolysate continued (up to 5 days) after growth had ceased.
Abstract: Net production of isobutyric acid, isovaleric acid, and 2-methylbutyric acid by cultures of Bacteroides ruminicola and Megasphaera elsdenii on media that contained Trypticase or casein hydrolysate continued (up to 5 days) after growth had ceased Only trace quantities of these acids were produced in a medium that contained a mixture of amino acids that did not include the branched-chain amino acids M elsdenii produced increased quantities of the branched-chain fatty acids in a medium that contained Trypticase when glucose was reduced or eliminated from the culture medium However, B ruminicola produced increased quantities of branched-chain fatty acids and of phenylacetic acid from Trypticase when glucose was supplied at 3 mg/ml rather than at 1 mg/ml Single strains of Streptococcus bovis, Selenomonas ruminantium, Bacteroides amylophilus, and Butyrivibrio fibrisolvens did not produce branched-chain fatty acids
TL;DR: The increased toxicity of zinc in the presence of high concentrations of NaCl was not a result of a synergistic interaction between Zn2+ and elevated osmotic pressures but of the formation of complex anionic ZnCl species that exerted greater toxicities than did cationic Zn 2+.
Abstract: A 10 mM concentration of Zn2+ decreased the survival of Escherichia coli; enhanced the survival of Bacillus cereus; did not significantly affect the survival of Pseudomonas aeruginosa, Norcardia corallina, and T1, T7, P1, and phi80 coliphages; completely inhibited mycelial growth of Rhizoctonia solani; and reduced mycelial growth of Fusarium solani, Cunninghamella echinulata, Aspergillus niger, and Trichoderma viride. The toxicity of zinc to the fungi, bacteria, and coliphages was unaffected, lessened, or increased by the addition of high concentrations of NaCl. The increased toxicity of zinc in the presence of high concentrations of NaCl was not a result of a synergistic interaction between Zn2+ and elevated osmotic pressures but of the formation of complex anionic ZnCl species that exerted greater toxicities than did cationic Zn2+. Conversely, the decrease in zinc toxicity with increasing concentrations of NaCl probably reflected the decrease in the levels of Zn2+ due to the formation of Zn-Cl species, which was less inhibitory to these microbes than was Zn2+. A. niger tolerated higher concentrations of zinc in the presence of NaCl at 37 than at 25 degrees C.
TL;DR: The particle size distribution for the four localities showed that about 50% of the particles carrying bacteria were larger than 8 micrometer, and an annual periodicity with high average counts found during summer and autumn could be seen.
Abstract: The concentration of airborne bacteria was recorded during a period of 3 years at four localities: (i) in an agricultural district with an average of 99 (range, 2 to 3,400) bacteria per m3; (ii) in a coastal area with an average of 63 (range, 0 to 560) bacteria per m3; (iii) in a city park with an average of 763 (range, 100 to 2,500) bacteria per m3; and (iv) in a city street with an average of 850 (range, 100 to 4,000) bacteria per m3. At all four localities the bacterial concentrations varied within broad limits, but an annual periodicity with high average counts found during summer and autumn could be seen. The influence of certain meteorological factors on the number of airborne bacteria is also reported. Rain or high relative humidity caused a decrease in the bacterial counts, while high temperature or high wind velocities increased the counts. The particle size distribution for the four localities showed that about 50% of the particles carrying bacteria were larger than 8 micrometer.
TL;DR: The results suggested that endogenous nuclease activity during the lysozyme treatment period initiated Lac plasmid DNA loss, and the development of an efficient lysis procedure for the group N streptococci allowed rapid identification and characterization of plasmids DNA by agarose gel electrophoresis.
Abstract: Procedures for effective cellular lysis and plasmid deoxyribonucleic acid (DNA) isolation from group N streptococci were developed. Cells were grown at 32 degrees C for 4 h in a modified Elliker broth containing 20 mM DL-threonine. After cellular digestion with 2 mg of lysozyme per ml for 7 min at 37 degrees C, 1% sodium dodecyl sulfate exposure resulted in complete and immediate lysis. Lactose (Lac) plasmid species in Streptococcus lactis C2 and S. cremoris B1 (30 and 37 megadaltons, respectively) were demonstrated upon examination of DNA from the cleared lysates by agarose gel electrophoresis. Increasing the lysozyme treatment to 20 min or more resulted in loss of the Lac plasmid, whereas other resident plasmids were unaffected and demonstrable in agarose gels. Diethylpyrocarbonate added before lysis prevented Lac plasmid loss in 20-min lysozyme-treated cells, but was not effective after 40 min of lysozyme treatment. The results suggested that endogenous nuclease activity during the lysozyme treatment period initiated Lac plasmid DNA loss. The development of an efficient lysis procedure for the group N streptococci allowed rapid identification and characterization of plasmid DNA by agarose gel electrophoresis. The plasmid composition of S. lactis C2 and S. cremoris B1, as determined by agarose gel electrophoresis, compared favorably to previous electron microscopic observations.
TL;DR: The data indicate that superoxide dismutase activity and oxygen reduction rates are important determinants related to the tolerance of anaerobic bacteria to oxygen.
Abstract: The effect of atmospheric oxygen on the viability of 13 strains of anaerobic bacteria, two strains of facultative bacteria, and one aerobic organism was examined. There were great variations in oxygen tolerance among the bacteria. All facultative bacteria survived more than 72 h of exposure to atmospheric oxygen. The survival time for anaerobes ranged from less than 45 min for Peptostreptococcus anaerobius to more than 72 h for two Clostridium perfringens strains. An effort was made to relate the degree of oxygen tolerance to the activities of superoxide dismutase, catalase, and peroxidases in cell-free extracts of the bacteria. All facultative bacteria and a number of anaerobic bacteria possessed superoxide dismutase. There was a correlation between superoxide dismutase activity and oxygen tolerance, but there were notable exceptions. Polyacrylamide gel electropherograms stained for superoxide dismutase indicated that many of the anaerobic bacteria contained at least two electrophoretically distinct enzymes with superoxide dismutase activity. All facultative bacteria contained peroxidase, whereas none of the anaerobic bacteria possessed measurable amounts of this enzyme. Catalase activity was variable among the bacteria and showed no relationship to oxygen tolerance. The ability of the bacteria to reduce oxygen was also examined and related to enzyme content and oxygen tolerance. In general, organisms that survived for relatively long periods of time in the presence of oxygen but demonstrated little superoxide dismutase activity reduced little oxygen. The effects of medium composition and conditions of growth were examined for their influence on the level of the three enzymes. Bacteria grown on the surface of an enriched blood agar medium generally had more enzyme activity than bacteria grown in a liquid medium. The data indicate that superoxide dismutase activity and oxygen reduction rates are important determinants related to the tolerance of anaerobic bacteria to oxygen.
TL;DR: Scanning electron microscopy of the intestinal epithelia of chicks revealed populations of microbes on the duodenal, ileal, and cecal mucosal surfaces.
Abstract: Facultatively anaerobic and strictly anaerobic bacteria colonizing the intestinal tracts of 14-day-old chicks fed a corn-based diet were enumerated, isolated, and identified. Colony counts from anaerobic roll tubes (rumen fluid medium) or aerobic plates (brain heart infusion agar) recovered from homogenates of the duodenum, upper and lower ileum, and cecum varied appreciably among samples from individual birds. Anaerobic and aerobic counts from the duodenum and ileum were similar. Anaerobic counts were highest from the cecum (0.7 X 10(11) to 1.6 X 10(11)/g of dry tissue) and exceeded aerobic plate counts by a factor of at least 10(2). Facultatively anaerobic groups (Streptococcus, Staphylococcus, Lactobacillus, and Escherichia coli) comprised the predominant flora of the duodenum and ileum, although large numbers of anaerobes (9 to 39% of the small intestine isolates), represented by species of Eubacterium, Propionibacterium, Clostridium, Gemmiger, and Fusobacterium, were also recovered. Strict anaerobes (anaerobic gram-positive cocci, Eubacterium, Clostridium Gemmiger, Fusobacterium, and Bacteriodes) made up nearly the entire microbial population of the cecum. Scanning electron microscopy of the intestinal epithelia of chicks revealed populations of microbes on the duodenal, ileal, and cecal mucosal surfaces.
TL;DR: Some evidence is presented in support of the hypothesis that the natural bacteria are adapted to conditions of nutrient starvation by becoming "dormant," existing for an unknown period of time in a reversible physiological state that reflects the availability of organic nutrients.
Abstract: It is now possible to obtain accurate total counts of the bacteria of natural waters with the use of acridine orange staining and epifluorescence microscopy. This approach can be coupled to highly sensitive measurements of heterotrophic activity using radioisotopes. To accomplish this, three variations of a "specific activity index" are suggested, based on different approaches to measuring heterotrophic activity with radiolabeled organic solutes. The denominator of each index is the direct count of bacteria from a given natural sample. Three numerators are presented, each of which has been shown to vary directly with heterotrophic bacterial activity: V(max), turnover rate, and direct uptake (at high substrate concentrations). Each approach is illustrated with data from estuarine and coastal waters of northeastern Massachusetts. The data show major differences in specific activity that accompany such habitat differences as distances within or offshore from an estuary and vertical location in the water column. These and other data suggest that specific activity is a valid indicator of the physiological state and metabolic role of the bacteria. Some evidence is presented in support of the hypothesis that the natural bacteria are adapted to conditions of nutrient starvation by becoming "dormant," existing for an unknown period of time in a reversible physiological state that reflects the availability of organic nutrients.