Showing papers in "Applied and Environmental Microbiology in 1980"
TL;DR: In all three regions studied, it appeared that a significant fraction of the total primary production was utilized by the bacterioplankton and that substantial growth could occur in the absence of large particles.
Abstract: The principal objective of this study was to quantify the rate of heterotrophic bacterioplankton production. Production was estimated by two approaches: (i) measurement of increasing bacterial abundance with time in filtered (3-μm pore size) seawater and (ii) estimation of bacterial deoxyribonucleic acid synthesis by tritiated thymidine incorporation in unfractionated seawater. The two approaches yielded comparable results when used at the Controlled Ecosystem Population Experiment (Saanich Inlet, British Columbia, Canada), at McMurdo Sound (Antarctica), and off Scripps Pier (La Jolla, Calif.). Estimated bacterioplankton production was lower in Antarctic samples (ranging from ∼0 to 2.9 μg of C liter−1 day−1) than in those from the other two sites (ranging from 0.7 to 71 μg of C liter−1 day−1). In all three regions studied, it appeared that a significant fraction of the total primary production was utilized by the bacterioplankton and that substantial growth could occur in the absence of large particles. These results support the conclusion that bacterioplankton are a quantitatively important component of coastal marine food webs.
921 citations
TL;DR: The results support the view that nitrification is an important source of N(2)O in the environment and that nitrite-oxidizing bacteria (Nitrobacter sp.) and the dinoflagellate Exuviaella sp.
Abstract: Pure cultures of the marine ammonium-oxidizing bacterium Nitrosomonas sp. were grown in the laboratory at oxygen partial pressures between 0.005 and 0.2 atm (0.18 to 7 mg/liter). Low oxygen conditions induced a marked decrease in the rate for production of NO2-, from 3.6 × 10−10 to 0.5 × 10−10 mmol of NO2- per cell per day. In contrast, evolution of N2O increased from 1 × 10−12 to 4.3 × 10−12 mmol of N per cell per day. The yield of N2O relative to NO2- increased from 0.3% to nearly 10% (moles of N in N2O per mole of NO2-) as the oxygen level was reduced, although bacterial growth rates changed by less than 30%. Nitrifying bacteria from the genera Nitrosomonas, Nitrosolobus, Nitrosospira, and Nitrosococcus exhibited similar yields of N2O at atmospheric oxygen levels. Nitrite-oxidizing bacteria (Nitrobacter sp.) and the dinoflagellate Exuviaella sp. did not produce detectable quantities of N2O during growth. The results support the view that nitrification is an important source of N2O in the environment.
759 citations
TL;DR: A new genus and species of a nonmotile gram-negative rod, Syntrophobacter wolinii, is the first bacterium described which degrades propionate only in coculture with an H(2)-using organism and in the absence of light or exogenous electron acceptors such as O(2), sulfate, or nitrate.
Abstract: A new genus and species of a nonmotile gram-negative rod, Syntrophobacter wolinii, is the first bacterium described which degrades propionate only in coculture with an H(2)-using organism and in the absence of light or exogenous electron acceptors such as O(2), sulfate, or nitrate. It was isolated from methanogenic enrichments from an anaerobic municipal sewage digestor, using anaerobic roll tubes containing a medium with propionate as the energy source in association with an H(2)-using, sulfate-reducing Desulfovibrio sp. which cannot utilize fatty acids other than formate. S. wolinii produced acetate and, presumably, CO(2) and H(2) (or formate) from propionate. In media without sulfate and with Methanospirillum hungatei, a methanogen that uses only H(2)-CO(2) or formate as an energy source, acetate, methane, and, presumably, CO(2) were produced from propionate and only small amounts of Desulfovibrio sp. were present. Isolation in coculture with the methanogen was not successful. S. wolinii does not use other saturated fatty acids as energy sources.
552 citations
TL;DR: A low pH appeared to have a detrimental effect on cell yields and large variations were seen among strains in both the magnitude of yield depressions at lower pH values and in the pH at which the culture washed out.
Abstract: A total of 10 strains of rumen bacteria, Selenomonas ruminantium HD4, Megasphaera elsdenii B159, Butyrivibrio fibrisolvens A38, Streptococcus bovis JB1, Lactobacillus vitulinus GA1, Bacteroides ruminicola B14, B. ruminicola GA33, Ruminococcus albus 7, Ruminococcus flavefaciens C94, and Bacteroides succinogenes S85, were grown in energy-limiteH of the medium reservoir was lowered approximately 0.3 pH units, and the energy source concentration remaining in the culture vessel, optical density, cell mass, and pH were determined. A low pH appeared to have a detrimental effect on cell yields. Large variations were seen among strains in both the magnitude of yield depressions at lower pH values and in the pH at which the culture washed out. Lactate analysis indicated ta are discussed in relation to the effect of pH on the efficiency of protein synthesis in the rumen and rumen microbial ecology.
449 citations
TL;DR: It was concluded that chlorate had relatively little inhibitory effect on ammonium oxidation, however, under some conditions chlorate was not completely effective in blocking nitrite oxidation, and the causes of this were investigated.
Abstract: A method was developed to determine the ammonium oxidation rate (potential) of unenriched natural samples by measuring the nitrite produced in shaken slurries. Addition of chlorate to the samples prevented nitrite from being oxidized to nitrate. The effectiveness and specificity of chlorate were tested with pure cultures of nitrite and ammonium oxidizers, as well as in soil and sediment slurries. It was concluded that chlorate had relatively little inhibitory effect on ammonium oxidation. However, under some conditions chlorate was not completely effective in blocking nitrite oxidation, and the causes of this were investigated. The technique was designed to check for incomplete blockage.
400 citations
TL;DR: A low water activity (alpha omega) medium containing 18% (wt/wt) glycerol and 2 micrograms of dichloran per ml was developed for enumerating the fungal flora of dried and semidried foods and was shown to be significantly better than Christensen malt salt agar when both media were tested with foodstuffs and with pure culture inocula.
Abstract: A low water activity (alpha omega) medium (0.95 alpha omega) containing 18% (wt/wt) glycerol and 2 micrograms of dichloran per ml was developed for enumerating the fungal flora of dried and semidried foods. The medium, designated DG18, was shown to be significantly better than Christensen malt salt agar when both media were tested with foodstuffs and with pure culture inocula. The need for a medium of reduced alpha omega for enumerating xerophilic fungi from low-moisture foods was demonstrated by comparing fungal counts obtained on both high-alpha omega and low-alpha omega media.
360 citations
TL;DR: Steaming treatment was the most effective extraction method for the activated sludges, since it released a significant quantity of extracellular polymers from the flocs and caused less cellular disruption than ethylenediaminetetraacetic acid and sodium hydroxide treatments.
Abstract: Five different bacterial extracellular polymer extraction methods and a combination of two of these methods were compared on cultures of activated sludge, synthetic activated sludge, and Klebsiella aerogenes. High-speed centrifugation was the most effective extraction method for the K. aerogenes culture, based on the comparatively small amount of cell disruption and the relatively high extracellular polymer yield. Steaming treatment was the most effective extraction method for the activated sludges, since it released a significant quantity of extracellular polymers from the flocs and caused less cellular disruption than ethylenediaminetetraacetic acid and sodium hydroxide treatments. Sodium hydroxide treatment caused extensive disruption in all cultures. Ultrasonication released low concentrations of extracellular polymers from all cultures. However, it caused no significant cell disruption and therefore may be useful as a preliminary treatment in conjunction with another extraction method.
321 citations
TL;DR: Identification of bacterial populations before and after contact with chlorine (1 to 2 mg/liter) for 1 h revealed that chlorination selected for gram-positive bacteria.
Abstract: Nearly 700 standard plate count (SPC) bacteria were isolated from drinking water and untreated surface water and identified according to a scheme developed to permit the rapid, simple classification of microorganisms to genus, species, or group. Actinomycetes and Aeromonas species were the two most common groups of SPC bacteria in chlorinated distribution water. Aeromonas spp. and Enterobacter agglomerans were the two most common groups of SPC bacteria in raw water. Identification of bacterial populations before and after contact with chlorine (1 to 2 mg/liter) for 1 h revealed that chlorination selected for gram-positive bacteria. Water that contained high densities of bacteria known to be antagonistic to coliforms had low coliform isolation rates. The membrane filtration technique for enumerating SPC bacteria recovered significantly higher numbers (P
273 citations
TL;DR: Temperature, soil moisture content, presence of aerobic microorganisms, degree of virus adsorption to the soil, soil levels of resin-extracted phosphorus, exchangeable aluminium, and soil pH appeared to be the most important factors affecting virus survival.
Abstract: Because of the increasing emphasis placed upon land application as a means of wastewater disposal, it is important to evaluate the influences of different factors upon virus survival in soil. The objective of this study was to measure the effects of various environmental variables on virus persistence. Test samples of soil were placed in vials, and the soil was wetted with suspensions of virus in either distilled water, unchlorinated secondary sewage effluent, or mixtures of effluent and water. The viruses used were coxsackieviruses A9 and B3, echovirus 1, poliovirus 2, rotavirus SA11, and bacteriophages T2 and MS2. The rate of virus inactivation was evaluated statistically with regard to conditions under which the vials were incubated and to the soil characteristics. The factors that were found to influence virus survival were temperature, soil moisture content, presence of aerobic microorganisms, degree of virus adsorption to the soil, soil levels of resin-extractable phosphorus, exchangeable aluminium, and soil pH. Overall, temperature and virus adsorption to soil appeared to be the most important factors affecting virus survival.
272 citations
TL;DR: In 11 species of rumen ciliates belonging to nine genera of the family Ophryoscolecidae an ectosymbiosis with methanogenic bacteria was found, which may reflect a metabolic interaction in which efficient interspecies hydrogen transfer benefits both partners.
Abstract: In 11 species of rumen ciliates belonging to nine genera of the family Ophryoscolecidae (order Entodiniomorphida) an ectosymbiosis with methanogenic bacteria was found. The bacteria could be identified as methanogens on the basis of the presence of specific fluorescent coenzymes (F350 and F420). This somatic interaction may reflect a metabolic interaction in which efficient interspecies hydrogen transfer benefits both partners. Images
268 citations
TL;DR: Colonization of grass root surfaces by A. brasilense is described and a possible explanation for the limited colonization of intercellular spaces of the outer root cortex is provided.
Abstract: The association between grass roots and Azospirillum brasilense Sp 7 was investigated by the Fahraeus slide technique, using nitrogen-free medium. Young inoculated roots of pearl millet and guinea grass produced more mucilaginous sheath (mucigel), root hairs, and lateral roots than did uninoculated sterile controls. The bacteria were found within the mucigel that accumulated on the root cap and along the root axes. Adherent bacteria were associated with granular material on root hairs and fibrillar material on undifferentiated epidermal cells. Significantly fewer numbers of azospirilla attached to millet root hairs when the roots were grown in culture medium supplemented with 5 mM potassium nitrate. Under these growth conditions, bacterial attachment to undifferentiated epidermal cells was unaffected. Aseptically collected root exudate from pearl millet contained substances which bound to azospirilla and promoted their adsorption to the root hairs. This activity was associated with nondialyzable and proteasesensitive substances in root exudate. Millet root hairs adsorbed azospirilla in significantly higher numbers than cells of Rhizobium, Pseudomonas, Azotobacter, Klebsiella, or Escherichia. Pectolytic activities, including pectin transeliminase and endopolygalacturonase, were detected in pure cultures of A. brasilense when this species was grown in a medium containing pectin. These studies describe colonization of grass root surfaces by A. brasilense and provide a possible explanation for the limited colonization of intercellular spaces of the outer root cortex.
TL;DR: The observed anoxic methane oxidation in Lake Mendota and digested sewage sludge was more sensitive to 2-bromoethanesulfonic acid than the simultaneous methane formation, and in the presence of iron and sulfate the ratio of methane oxidized to methane formed increased markedly.
Abstract: Anoxic sediments and digested sewage sludge anaerobically oxidized methane to carbon dioxide while producing methane. This strictly anaerobic process showed a temperature optimum between 25 and 37°C, indicating an active microbial participation in this reaction. Methane oxidation in these anaerobic habitats was inhibited by oxygen. The rate of the oxidation followed the rate of methane production. The observed anoxic methane oxidation in Lake Mendota and digested sewage sludge was more sensitive to 2-bromoethanesulfonic acid than the simultaneous methane formation. Sulfate diminished methane formation as well as methane oxidation. However, in the presence of iron and sulfate the ratio of methane oxidized to methane formed increased markedly. Manganese dioxide and higher partial pressures of methane also stimulated the oxidation. The rate of methane oxidation in untreated samples was approximately 2% of the CH4 production rate in Lake Mendota sediments and 8% of that in digested sludge. This percentage could be increased up to 90% in sludge in the presence of 10 mM ferrous sulfate and at a partial pressure of methane of 20 atm (2,027 kPa).
TL;DR: The results indicate that the specific action of sulfide rather than the low redox potential caused a partial inhibition of NO reduction and a strong inhibition of N2O reduction in denitrifying cells.
Abstract: The influence of low redox potentials and H2S on NO and N2O reduction by resting cells of denitrifying Pseudomonas fluorescens was studied. Hydrogen sulfide and Ti(III) were added to achieve redox potentials near -200 mV. The control without reductant had a redox potential near +200 mV. Production of 13NO, [13N]N2O, and [13N]N2 from 13NO3- and 13NO2- was followed. Total gas production was similar for all three treatments. The accumulation of 13NO was most significant in the presence of sulfide. A parallel control with autoclaved cells indicated that the 13NO production was largely biological. The sulfide inhibition was more dramatic at the level of N2O reduction; [13N]N2O became the major product instead of [13N]N2, the dominant product when either no reductant or Ti(III) was present. The results indicate that the specific action of sulfide rather than the low redox potential caused a partial inhibition of NO reduction and a strong inhibition of N2O reduction in denitrifying cells.
TL;DR: The inhibitory effects of 29 commercial powdered spices on the growth and toxin production of three species of toxigenic Aspergillus were observed by introducing these materials into culture media for mycotoxin production.
Abstract: The inhibitory effects of 29 commercial powdered spices on the growth and toxin production of three species of toxigenic Aspergillus were observed by introducing these materials into culture media for mycotoxin production. Of the 29 samples tested, cloves, star anise seeds, and allspice completely inhibited the fungal growth, whereas most of the others inhibited only the toxin production. Eugenol extracted from cloves and thymol from thyme caused complete inhibition of the growth of both Aspergillus flavus and Aspergillus versicolor at 0.4 mg/ml or less. At a concentration of 2 mg/ml, anethol extracted from star anise seeds inhibited the growth of all the strains.
TL;DR: Results indicate that the ability of populations to adapt depends on the presence of specific microorganisms, and adaptation must be considered when such systems are used to predict the fate of xenobiotics in the environment.
Abstract: Experiments were devised to determine whether exposure to xenobiotics would cause microbial populations to degrade the compounds more rapidly during subsequent exposures. Studies were done with water/sediment systems (ecocores) taken from a salt marsh and a river. Systems were tested for adaptation to the model compounds methyl parathion and p-nitrophenol. CO(2) released from radioactive parent compounds was used as a measure of mineralization. River populations preexposed to p-nitrophenol at concentrations as low as 60 mug/liter degraded the nitrophenol much faster than did control populations. River populations preexposed to methyl parathion also adapted to degrade the pesticide more rapidly, but higher concentrations were required. Salt marsh populations did not adapt to degrade methyl parathion. p-Nitrophenol-degrading bacteria were isolated from river samples but not from salt marsh samples. Numbers of nitrophenol-degrading bacteria increased 4 to 5 orders of magnitude during adaptation. Results indicate that the ability of populations to adapt depends on the presence of specific microorganisms. Biodegradation rates in laboratory systems can be affected by concentration and prior exposure; therefore, adaptation must be considered when such systems are used to predict the fate of xenobiotics in the environment.
TL;DR: As determined by these techniques, a marine settling community showed greater differences in bacterial as contrasted to microeucaryotic populations when compared with the microbial communities of benthic cores.
Abstract: Fatty acids are a widely studied group of lipids of sufficient taxonomic diversity to be useful in defining microbial community structure The extraordinary resolution of glass capillary gas-liquid chromatography can be utilized to separate and tentatively identify large numbers of fatty acid methyl esters derived from the lipids of estuarine detritus and marine benthic microbiota without the bias of selective methods requiring culture or recovery of the microbes The gas-liquid chromatographic analyses are both reproducible and highly sensitive, and the recovery of fatty acids is quantitative The analyses can be automated, and the diagnostic technique of mass spectral fragmentation analysis can be readily applied Splitless injection on glass capillary gas chromatographic columns detected by mass spectral selective ion monitoring provides an ultrasensitive and definitive monitoring system Reciprocal mixtures of bacteria and fungi, when extracted and analyzed, showed progressive changes of distinctive fatty acid methyl esters derived from the lipids By manipulating the environment of an estuarine detrital microbial community with antibiotics and culture conditions, it was possible to produce a community greatly enriched in eucaryotic fungi, as evidenced by scanning electron microscopic morphology The fatty acid methyl esters from the lipids in the fungus-enriched detritus showed enrichment of the C18 dienoic and the C18 and C20 polyenoic esters Manipulation of the detrital microbiota that increased the procaryotic population resulted in an absence of large structures typical of fungal mycelia or diatoms, as evidenced by scanning electron microscopy, and a significantly larger proportion of anteiso- and isobranched C15 fatty acid esters, C17 cyclopropane fatty acid esters, and the cis-vaccenic isomer of the C18 monoenoic fatty acid esters As determined by these techniques, a marine settling community showed greater differences in bacterial as contrasted to microeucaryotic populations when compared with the microbial communities of benthic cores
TL;DR: The ability of CO(2) to inhibit respiration and growth of representative strains of seven species of meat spoilage bacteria was examined and Enterobacter and Microbacterium thermosphactum were unaffected, while both respirationand growth of the other species were inhibited.
Abstract: The ability of CO2 to inhibit respiration and growth of representative strains of seven species of meat spoilage bacteria was examined. Enterobacter and Microbacterium thermosphactum were unaffected by CO2. Both respiration and growth of the other species were inhibited. With four of the species (fluorescent and nonfluorescent Pseudomonas, Alteromonas putrefaciens, and Yersinia enterocolitica), the inhibition pattern in a complex medium was similar, and inhibition was incomplete and reached a maximum level at comparatively low concentrations of CO2. With Acinetobacter, inhibition continued to increase with increasing CO2 concentration. The degree of inhibition with a constant concentration of CO2 in solution increased with decreasing temperature for all CO2-susceptible species except the nonfluorescent Pseudomonas. Anaerobic growth of CO2-susceptible facultative anaerobes was unaffected by CO2.
TL;DR: The DC media were found by plating techniques to be suitable for differentiating mixed rumen bacterial populations into subgroups based upon carbohydrate utilization as shown by differences in subgroup profiles found within solid and liquid fractions of rumen contents.
Abstract: A basal (BC) medium devoid of added carbohydrates, a complete (CC) medium containing nine carbohydrates were developed for enumerating rumen bacteria The colony counts on the BC medium were 85 to 100% of those obtained on the CC medium These colonies were pinpoint size (less than or equal to mm in diameter) but increased in size (2 to 5 mm in diameter) when carbohydrates were subsequently added With the CC medium or other media tested, the colony counts were 20 to 50% higher on plates than on roll tubes and were about 35% of the direct cell counts The lower colony counts on roll tubes were shown to result primarily from the loss of viability due to heat stress The DC media were found by plating techniques to be suitable for differentiating mixed rumen bacterial populations into subgroups based upon carbohydrate utilization as shown by differences in subgroup profiles found within solid and liquid fractions of rumen contents, within rumen contents from animals fed high-forage and high-grain diets, and by correct colony formations by pure cultures of rumen bacteria on appropriate DC media With simple modifications and use of an anaerobic glove box, replica plating methods and the CC and DC media were found to be a suitable means of rapidly determining the range of utilizable carbohydrate energy sources of rumen bacteria
TL;DR: Sediment pH and oxidation-reduction potential were important factors in governing the population of hydrocarbon-degrading microorganisms in the sediment and subsequent mineralization rates.
Abstract: Microbial mineralization rates of two petroleum hydrocarbons, as affected by pH and oxidation-reduction potential, were determined in a Barataria Bay, Louisiana, sediment using 14C-labeled hydrocarbons. Hydrocarbon mineralization rates were inferred from the activity of respired 14CO2. Sediment pH and oxidation-reduction potential were important factors in governing the population of hydrocarbon-degrading microorganisms in the sediment and subsequent mineralization rates. Highest mineralization rates occurred at pH 8.0, and the lowest occurred at pH 5.0. At all pH levels mineralization decreased with decreasing oxidation-reduction potential (i.e., increasing sediment anaerobiosis). Generally, mineralization rates for octadecane were greater than those for naphthalene. Aerobic microorganisms in the oxidized sediment were more capable of degrading hydrocarbons than anaerobic microorganisms in reduced sediment of the same pH.
TL;DR: Membrane filtration and epifluorescent microscopy were used for the direct enumeration of bacteria in raw milk and differences between counts obtained by different operators and between the membrane clump count and plate count were not significant.
Abstract: Membrane filtration and epifluorescent microscopy were used for the direct enumeration of bacteria in raw milk. Somatic cells were lysed by treatment with trypsin and Triton X-100 so that 2 ml of milk containing up to 5 x 10 somatic cells/ml could be filtered. The majority of the bacteria (ca. 80%) remained intact and were concentrated on the membrane. After being stained with acridine organe, the bacteria fluoresced under ultraviolet light and could easily be counted. The clump count of orange fluorescing cells on the membrane correlated well (r = 0.91) with the corresponding plate count for farm, tanker, and silo milks. Differences between counts obtained by different operators and between the membrane clump count and plate count were not significant. The technique is rapid, taking less than 25 min, inexpensive, costing less than 50 cents per sample, and is suitable for milks containing 5 x 10 to 5 x 10 bacteria per ml.
TL;DR: Observations indicate that the temperature, pH, and nutritional requirements of L. pneumophila are not as stringent as those previously observed when cultured on complex media and suggests an explanation for the apparent widespread distribution of the bacterium in nature.
Abstract: Legionella pneumophila (Legionnaires disease bacterium) of serogroup 1 was isolated from an algal-bacterial mat community growing at 45 degrees C in a man-made thermal effluent. This isolate was grown in mineral salts medium at 45 degrees C in association with the blue-green alga (cyanobacterium) Fischerella sp. over a pH range of 6.9 to 7.6. L. pneumophila was apparently using algal extracellular products as its carbon and energy sources. These observations indicate that the temperature, pH, and nutritional requirements of L. pneumophila are not as stringent as those previously observed when cultured on complex media. This association between L. pneumophila and certain blue-green algae suggests an explanation for the apparent widespread distribution of the bacterium in nature.
TL;DR: Although sandy and organic soil materials were poor virus adsorbents when suspended in wastewater, they gave >/=95% virus removal from intermittently applied wastewater as unsaturated, 10-cm-deep columns, however, considerable quantities of the retained viruses were washed from the columns by simulated rainfall.
Abstract: There were marked differences in the abilities of eight different soil materials to remove and retain viruses from settled sewage, but for each soil material the behavior of two different viruses, poliovirus type 1 and reovirus type 3, was often similar. Virus adsorption to soil materials was rapid, the majority occurring within 15 min. Clayey materials efficiently adsorbed both viruses from wastewater over a range of pH and total dissolved solids levels. Sands and organic soil materials were comparatively poor adsorbents, but in some cases their ability to adsorb viruses increased at low pH and with the addition of total dissolved solids or divalent cations. Viruses in suspensions of soil material in settled sewage survived for considerable time periods, despite microbial activity. In some cases virus survival was prolonged in suspensions of soil materials compared to soil-free controls. Although sandy and organic soil materials were poor virus adsorbents when suspended in wastewater, they gave ≥95% virus removal from intermittently applied wastewater as unsaturated, 10-cm-deep columns. However, considerable quantities of the retained viruses were washed from the columns by simulated rainfall. Under the same conditions, clayey soil material removed ≥99.9995% of the viruses from applied wastewater, and none were washed from the columns by simulated rainfall.
TL;DR: Biological mercury methylation was assayed by a new radiochemical technique in the water column and sediments of a mercury-contaminated lake during 24 weeks during 1979.
Abstract: Biological mercury methylation was assayed by a new radiochemical technique in the water column and sediments of a mercury-contaminated lake. In 24 weeks during 1979, there were three episodes of methylating activity in surface floc and in water, each lasting 3 to 5 weeks. Periods of methylation in the water column coincided with surface sediment methylation and appeared to be related to overall microbial activity. Mercury was actively methylated in the presence of bound sulfide.
TL;DR: The Douglas fir terpene alpha-pinene was shown to inhibit the growth of a variety of bacteria and a yeast and to strongly influence the infectivity of B. thuringiensis spores for the Douglas fir tussock moth larvae.
Abstract: The Douglas fir terpene α-pinene was shown to inhibit the growth of a variety of bacteria and a yeast. Other terpenes of the Douglas fir, including limonene, camphene, and isobornyl acetate, were also inhibitory to Bacillus thuringiensis. All terpenes were inhibitory at concentrations normally present in the fir needle diet of Douglas fir tussock moth larvae. The presence of such terpenes in the diet of these insects was found to strongly influence the infectivity of B. thuringiensis spores for the Douglas fir tussock moth larvae. The terpene α-pinene destroyed the cellular integrity and modified mitochondrial activity in certain microorganisms.
TL;DR: The virus adsorption behavior of Virozorb 1MDS and Filterite pleated cartridge filters appears to be related to their surface charge properties, with more electropositive filters giving more efficient virus Adsorption from tap water at higher pH levels.
Abstract: Simple, reliable, and efficient concentration of poliovirus from tap water was obtained with two types of electropositive filter media, one of which is available in the form of a pleated cartridge filter (Virozorb 1MDS). Virus adsorption from tap water between pH 3.5 and 7.5 was more efficient with electropositive filters than with Filterite filters. Elution of adsorbed viruses was more efficient with beef extract in glycine, pH 9.5, than with glycine-NaOH, pH 11.0. In paired comparative studies, electropositive filters, with adsorption at pH 7.5 and no added polyvalent cation salts, gave less variable virus concentration efficiencies than did Filterite filters with adsorption at pH 3.5 plus added MgCl2. Recovery of poliovirus from 1,000-liter tap water volumes was approximately 30% efficient with both Virozorb 1MDS and Filterite pleated cartridge filters, but the former were much simpler to use. The virus adsorption behavior of these filters appears to be related to their surface charge properties, with more electropositive filters giving more efficient virus adsorption from tap water at higher pH levels.
TL;DR: A modified medium which distinguished between citrate-fermenting and non-citrate-Fermenting species of lactic streptococci within 48 h was developed and the occurrence of citrates-negative variants in citrate -positive populations of Streptococcus lactis subsp.
Abstract: A modified medium which distinguished between citrate-fermenting and non-citrate-fermenting species of lactic streptococci within 48 h was developed. In addition, the occurrence of citrate-negative variants in citrate-positive populations of Streptococcus lactis subsp. diacetylactis could be detected. Images
TL;DR: A new culture method employing a potassium hydroxide treatment was compared with the conventional cold enrichment method for efficacy in recovering Yersinia sp.
Abstract: A new culture method employing a potassium hydroxide treatment was compared with the conventional cold enrichment method for efficacy in recovering Yersinia sp. from naturally and artificially contaminated food. The new method increased the yield of Yersinia sp. fourfold and the sensitivity 100-fold, shortened the incubation period, and appreciably decreased the growth of non-Yersinia bacteria from a variety of meats, shellfish, and vegetables.
TL;DR: The growth of Clostridium thermocellum ATCC 27405 and of C9, an ethanol-resistant mutant of this strain, at different ethanol concentrations and temperatures was characterized and the wild-type strain showed a higher energy of activation for growth than the ethanol-tolerant derivative.
Abstract: The growth of Clostridium thermocellum ATCC 27405 and of C9, an ethanol-resistant mutant of this strain, at different ethanol concentrations and temperatures was characterized After ethanol addition, cultures continued to grow for 1 to 2 h at rates similar to those observed before ethanol was added and then entered a period of growth arrest, the duration of which was a function of the age of inocula After this period, cultures grew at an exponential rate that was a function of ethanol concentration The wild-type strain showed a higher energy of activation for growth than the ethanol-tolerant derivative The optimum growth temperature of the wild type decreased as the concentration of the ethanol challenge increased, whereas the optimum growth temperature for C9 remained constant The results are discussed in terms of what is known about the effects of ethanol and temperature on membrane composition and fluidity
TL;DR: A polyacrylamide slab gel electrophoresis procedure was used to compare cellular proteins from bacterial isolates of gingival crevice floras and provided additional verification of the identity of strains characterized by conventional phenotypic tests.
Abstract: A polyacrylamide slab gel electrophoresis procedure was used to compare cellular proteins from bacterial isolates of gingival crevice floras. Isolates with identical protein patterns consistently were shown to be members of the same species. When used to screen isolates, the procedure reduced total analytical time and expense without sacrificing accuracy, and it provided additional verification of the identity of strains characterized by conventional phenotypic tests. Images
TL;DR: Transduction and transformation were ruled out as the mechanism of genetic exchange in strains ML3, DRC3, 11007, and WM(4), nor was reversion responsible for the high number of Lac(+) Str(r) recombinants.
Abstract: Streptococcus lactis strains ML3 and C 2 O and S. lactis subsp. diacetylactis strains DRC3, 11007, and WM 4 were found to transfer lactose-fermenting ability to LM0230, an S. lactis C2 lactose-negative (Lac − ) derivative which is devoid of plasmid deoxyribonucleic acid (DNA). Lactose-positive streptomycin-resistant (Lac + Str r ) recombinants were found when the Lac + Str s donor was mixed with Lac − Str r LM0230 in solid-surface matings. Transduction and transformation were ruled out as the mechanism of genetic exchange in strains ML3, DRC3, 11007, and WM 4 , nor was reversion responsible for the high number of Lac + Str r recombinants. Furthermore, chloroform treatment of the donor prevented the appearance of recombinants, indicating that transfer of lactose-fermenting ability required viable cell-to-cell contact. Strain C 2 O demonstrated transduction as well as conjugation. Transfer of plasmid DNA during conjugation for all strains was confirmed by demonstrating the presence of plasmid DNA in the transconjugants by using agarose gel electrophoresis. In some instances, a cryptic plasmid was transferred in conjunction with the lactose plasmid by using strains DRC3, 11007, and WM 4 . In S. lactis C2 × LM0230 matings, the Str r marker was transferred from LM0230 to C2, suggesting conjugal transfer of chromosomal DNA. The results confirm conjugation as another mechanism of genetic exchange occurring in dairy starter cultures. Images