Effect of biodelignification of rice straw on humification and humus quality by Phanerochaete chrysosporium and Streptomyces badius

The effect of biodelignification of rice straw by two different ligninolytic organisms, Phanerochaete chrysosporium (white-rot fungus) and Streptomyces badius (actinomycetes), on humus quality was investigated during a 56-day incubation at 30 °C. Lignin degradation, the release of humic extract (HE), humic acid (HA) and fulvic acid (FA), E4/E6 ratio of HA, and humification index (HI, HA/FA) were measured during the incubation. Lignin was degraded by both organisms, but to different extents. Lignin was degraded to 41% and 31% by P. chrysosporium and S. badius, respectively. HE released by P. chrysosporium and S. badius were, respectively, 2.10 and 2.13 times larger than that in the control at the maximum values. A significant correlation between lignin degradation and humus-related parameters involving HA fraction showed that both organisms are converting lignin to humic substances.     

Degradation of Alachlor [2-chloro-N-(methoxymethyl)-2′,6′-diethylacetanilide] by soil fungi

Summary A Penicillium sp. and a Trichoderma sp. were isolated from a soil previously treated with alachlor which is commonly used as herbicide. These fungi were found to degrade alachlor and only one degradation product was observed after 15 days of incubation. Whereas two products were noticed after 30 days with both the test organisms. re]19740913     

Further observations on the phagocytosis of Candida albicans by hamster and human oocytes

Pathogenic yeast, Candida albicans, were incubated with hamster and human oocytes for up to 21 hours in order to determine the nature and time course of phagocytosis of these organisms. Aliquotes of the interacting cells were taken at various time intervals for electron microscopic examination. Some specimens had their zona pellucidae enzymatically removed prior to incubation with yeast, and these specimens showed the most extensive interaction and phagocytosis of Candida. The zona pullucida appears to be an effective barrier to yeast, at least over the time span studied. The observations are consistent with the hypothesis of an initial attachment of yeast via a surface component to oocyte microvilli followed by phagocytic uptake into an endosome. There is no compelling evidence of lysosomal degradation of the yeast over the time course of this study; however, the oocytes appear to undergo some degenerative changes at long incubation times.     

Bacteriophage resistance of attached organisms as a factor in the survival of plasmid-bearing strains of Escherichia coli

Unattached organisms of plasmid-free and plasmid-bearing strains of Escherichia coli showed marked sensitivity to phages T4, Tula and K3 on incubation in broth at 37°C but organisms attached to glass beads or sand were resistant. Phage T4 sensitivity of free organisms and resistance of glass bead-attached ones were also observed when incubation was in broth at 15° or 20°C or anaerobically at 37°C. In contrast, free and attached organisms were resistant at 37°C or lower temperature when incubation was in poor media. It seems likely that the presence of phage will be a major factor reducing survival in the intestine and in sewage and that attachment (which is more significant for strains bearing certain plasmids) will protect. In contrast, survival of either free or attached organisms in polluted water will probably not be significantly influenced by the presence of phage.     

Enrichment of thermophilic syntrophic anaerobic glutamate-degrading consortia using a dialysis membrane reactor

A dialysis cultivation system was used to enrich slow-growing moderately thermophilic anaerobic bacteria at high cell densities. Bicarbonate buffered mineral salts medium with 5 mM glutamate as the sole carbon and energy source was used and the incubation temperature was 55 degrees C. The reactor inoculum originated from anaerobic methanogenic granular sludge bed reactors. The microbial population was monitored over a period of 2 years using the most probable number (MPN) technique. In the reactor glutamate was readily degraded to ammonium, methane, and carbon dioxide. Cell numbers of glutamate-degrading organisms increased 400-fold over the first year. In medium supplemented with bromoethane sulfonic acid (BES, an inhibitor of methanogenesis), tenfold lower cell numbers were counted, indicating the syntrophic nature of glutamate degradation. After 2 years of reactor operation the predominant organisms were isolated and characterized. Methanobacterium thermoautotrophicum (strain R43) and a Methanosaeta thermophila strain (strain A) were the predominant hydrogenotrophic and acetoclastic methanogens, respectively. The numbers in which the organisms were present in the reactor after 24 months of incubation were 8.6 x 10(9) and 3.8 x 10(7) mL(-1) sludge, respectively. The most predominant glutamate-degrading organism (8.6 x 10(7) mL(-1) sludge), strain Z, was identified as a new species, Caloramator coolhaasii. It converted glutamate to hydrogen, acetate, some propionate, ammonium, and carbon dioxide. Growth of this syntrophic organism on glutamate was strongly enhanced by the presence of methanogens.     

Effects of enrichment with phthalate on polycyclic aromatic hydrocarbon biodegradation in contaminated soil

The effect of enrichment with phthalate on the biodegradation of polycyclic aromatic hydrocarbons (PAH) was tested with bioreactor-treated and untreated contaminated soil from a former manufactured gas plant (MGP) site. Soil samples that had been treated in a bioreactor and enriched with phthalate mineralized (14)C-labeled phenanthrene and pyrene to a greater extent than unenriched samples over a 22.5-h incubation, but did not stimulate benzo[a]pyrene mineralization. In contrast to the positive effects on (14)C-labeled phenanthrene and pyrene, no significant differences were found in the extent of biodegradation of native PAH when untreated contaminated soil was incubated with and without phthalate amendment. Denaturing-gradient gel electrophoresis (DGGE) profiles of bacterial 16S rRNA genes from unenriched and phthalate-enriched soil samples were substantially different, and clonal sequences matched to prominent DGGE bands revealed that beta-Proteobacteria related to Ralstonia were most highly enriched by phthalate addition. Quantitative real-time PCR analyses confirmed that, of previously determined PAH-degraders in the bioreactor, only Ralstonia-type organisms increased in response to enrichment, accounting for 89% of the additional bacterial 16S rRNA genes resulting from phthalate enrichment. These findings indicate that phthalate amendment of this particular PAH-contaminated soil did not significantly enrich for organisms associated with high molecular weight PAH degradation or have any significant effect on overall degradation of native PAH in the soil.     

Grass cells ingested by ruminants undergo autolysis which differs from senescence: implications for grass breeding targets and livestock production

It is widely believed that the initial degradation of proteins contained in grazed forage is mediated by rumen micro‐organisms, but the authors’ recent work suggests that the plant cells themselves contribute to their own demise. In the present study the responses of Lolium perenne leaves to the rumen environment were investigated by using an in vitro system which simulates the main stresses of the rumen but from which rumen micro‐organisms were excluded. Degradation of leaf protein and the accumulation of amino acids in tissue and bathing medium occurred over a time‐scale that is relevant to rumen function, and in a near 1 : 1 ratio. Significant loss of nuclear material was observed after 6 h incubation and chloroplasts became morphologically more spherical as the incubation progressed. In situ localization suggested that ribulose 1,5 bisphosphate carboxylase/oxygenase was broken down within chloroplasts which from cytology were judged to be intact. We conclude from these data that plant metabolism may play a significant role in breaking down plant proteins within relatively intact organelles in the rumen. The determinations of chlorophyll content and cell viability revealed that the plant processes occurring in the simulated rumen were similar but not identical to those of natural senescence.     

Differential Effects of Oxygen and Oxidation Reduction Potential on the Multiplication of Three Species of Anaerobic Intestinal Bacteria

The sensitivity of three strains of anaerobic intestinal bacteria, Clostridium perfringens, Bacteroides fragilis, and Peptococcus magnus, to the differential effects of oxygen and adverse oxidation-reduction potential was measured. The multiplication of the three organisms was inhibited in the presence of oxygen whether the medium was at a negative oxidation-reduction potential (Eh of -50 mV), poised by the intermittent addition of dithiothreitol, or at a positive oxidation-reduction potential (Eh of near +500 mV). However, when these organisms were cultured in the presence of oxygen, no inhibition was observed, even when the oxidation-reduction potential was maintained at an average Eh of +325 mV by the addition of potassium ferricyanide. When the cultures were aerated, the growth patterns of the three organisms demonstrated different sensitivities to oxygen. P. magnus was found to be the most sensitive. After 2 h of aerobic incubation, no viable organisms could be detected. B. fragilis was intermediately sensitive to oxygen with no viable organisms detected after 5 h of aerobic incubation. C. perfringens was the least sensitive. Under conditions of aerobic incubation, viable organisms survived for 10 h. During the experiments with Clostridium, no spores were observed by spore staining.     

Differential antimicrobial activity of human mononuclear phagocytes against the human biovars of Chlamydia trachomatis

The antimicrobial activities of human mononuclear phagocytes against Chlamydia trachomatis were investigated. Phagocytes cultured for 7 days or less were efficiently microbicidal. Almost complete inactivation of organisms from both human biovars was observed after 48 hr of incubation. However, organisms from the lymphogranuloma venereum (LGV) biovar survived in mononuclear phagocytes infected after 8 days or more in culture, whereas those from the trachoma biovar continued to be killed by such cells. Phagocytes cultured as long as 21 days killed the trachoma organisms with the same effectiveness as those cultured for 7 days or less. An ultrastructural study of inoculated phagocytes illustrated phagolysosomal fusion with degradation of organisms from either biovar in phagocytes which had been cultured for 24 hr before infection. Phagolysosomal fusion was not observed in cells which had been cultured for 8 days or more and then infected with LGV. The addition of interferon-gamma to these macrophages partially restored the phagocytes' microbicidal activity for LGV. Furthermore, a synergistic effect was observed when eosinophil peroxidase was added with interferon. Specific antibody failed to neutralize the infectivity of LGV organisms in 8-day or older mononuclear phagocytes. The findings may reflect the differences in disease syndromes between the two biovars, with the trachoma biovar causing more peripheral diseases and the LGV biovar causing a more systemic disease, with lymph node involvement as its main syndrome.     

Production of lower-trophic organisms during incubation of unaltered deep-sea water

Incubation of unaltered deep-sea water and grazing experiment of nano- and micro- protozooplankton during incubation of deep-sea water were carried out to quantitatively characterize the planktonic structures of lower-trophic organisms and clarify the trophic pathways and controlling mechanisms involved. Phytoplankton biomass increased to 637 mg as carbon weight in a 500-l tank on Day 7 and was dominant in the planktonic structure of lower-trophic organisms. Nitrates in the incubation water was depleted after Day 7 and phytoplankton biomass decreased rapidly. On the other hand, bacteria, heterotrophic nano-flagellates and ciliates increased toward the end of incubation and were dominant in the later days of incubation. In grazing experiments on microbial organisms, bacterivory is more important for the carbon pathway in microbial food webs than herbivory when phytoplankton biomass is less than that of bacteria (low P/B conditions), while herbivory is more important than bacterivory when phytoplankton biomass is more than that of bacteria (high P/B conditions). Deep-sea water exhibited high phytoplankton productivity due to inherent high nutrients values. After depletion of nutrients, phytoplankton decreased (due also to enhanced nano- and micro-zooplankton grazing) and microbial organisms dominated. Thus, nutrients in the incubation water control the planktonic structure of lower-trophic organisms.     

Behavior of Vibrio cholerae in hot foods.

Four food types held hot at 45 to 60 degrees C were deliberately contaminated with O1 and non-O1 Vibrio cholerae strains. These organisms were assayed for survival and recovery from the foods within 1 h of the time the food was kept hot. The results showed no growth of V. cholerae non-O1 on thiosulfate-citrate bile-sucrose agar plates after 24 h of incubation at 37 degrees C for food held hot at 50 to 60 degrees C. Growth was low for V. cholerae O1 and was not achieved in some instances in which foods were held at either 55 or 60 degrees C after 40 or 60 min of from the time the food was kept hot. Both organisms, however, were recovered equally from all food types held at all temperatures after 48 h of incubation. When incubated for an additional 24 h, the organisms grew to unusually small-sized colonies, measuring 0.1 to 0.3 mm in diameter, on the same agar plates that were negative for growth after an initial 24 h of incubation. It was concluded that V. cholerae survived the period of time held at hot temperatures. Although the organisms were not recovered from some foods when held at some of the temperatures and times after 24 h of incubation, they remained viable. An incubation period of 48 h at 37 degrees C was found to be appropriate for the recovery of V. cholerae from hot foods.     

Behavior of Vibrio cholerae in hot foods

Four food types held hot at 45 to 60 degrees C were deliberately contaminated with O1 and non-O1 Vibrio cholerae strains. These organisms were assayed for survival and recovery from the foods within 1 h of the time the food was kept hot. The results showed no growth of V. cholerae non-O1 on thiosulfate-citrate bile-sucrose agar plates after 24 h of incubation at 37 degrees C for food held hot at 50 to 60 degrees C. Growth was low for V. cholerae O1 and was not achieved in some instances in which foods were held at either 55 or 60 degrees C after 40 or 60 min of from the time the food was kept hot. Both organisms, however, were recovered equally from all food types held at all temperatures after 48 h of incubation. When incubated for an additional 24 h, the organisms grew to unusually small-sized colonies, measuring 0.1 to 0.3 mm in diameter, on the same agar plates that were negative for growth after an initial 24 h of incubation. It was concluded that V. cholerae survived the period of time held at hot temperatures. Although the organisms were not recovered from some foods when held at some of the temperatures and times after 24 h of incubation, they remained viable. An incubation period of 48 h at 37 degrees C was found to be appropriate for the recovery of V. cholerae from hot foods.     

Isolation and characterization of potential aerobic bacteria capable for pyridine degradation in presence of picoline,phenol and formaldehyde as co-pollutants

Pyridine, heterocyclic aromatic compound is known to be toxic, carcinogenic and teratogenic to several living organisms. In this study, two aerobic bacteria ITRCEM1 and ITRCEM2 capable for pyridine degradation were isolated and characterized as Bacillus cereus (DQ435020) and Alcaligenes faecalis (DQ435021), respectively. For pyridine degradation, mixed bacterial culture was found more effective compared to axenic culture ITRCEM1 and ITRCEM2 degrading 94.23, 67.84, and 83.35% pyridine, respectively, at 144 h incubation period at pH 7.0 ± 0.1, temp 37 ± 2°C and shaking rate 125 rpm in MSM containing 1% glucose and 0.2% peptone as carbon and nitrogen source, respectively. The presence of phenol and formaldehyde in MSM has shown inhibitory effect on pyridine degradation whereas picoline has favored the bacterial growths and pyridine degradation. Further, the HPLC analysis has shown the reduction in peaks compared to controls, indicating that reduction in peak area might be largely attributed to the bacterial degradation of pyridine by bacterial catabolic enzymes.     

Action of Microorganisms on Bituminous Materials: I. Effect of Bacteria on Asphalt Viscosity

Visual effects of Mycobacterium ranae on a 135-penetration asphalt (asphalt 1A) are described, which show the texture and rheological characteristics of the asphalt to be modified by microbial action. A bentonite-asphalt emulsion system for asphalts 1A, 3A, and 6A was used to subject these materials to the degradative activity of M. ranae and Nocardia coeliaca for 4 months at 30 C. N. coeliaca caused 1.5-, 3.9-, and 6.8-fold increases in relative viscosity of asphalts 1A, 3A, and 6A, respectively. A similar susceptibility pattern for M. ranae was obtained on the same asphalts, but apparently this organism exerted even a greater effect on asphalt 6A since the viscosity of this residue was too hard to be determined satisfactorily. Comparison of these data with analyses of the three asphalts indicates that the organisms probably attack the resin components of the asphalts.     

Enhanced biodegradation of methoxychlor in soil under sequential environmental conditions.

Ring-U-[14C]methoxychlor [1,1-bis(p-methoxyphenyl)-2,2,2-trichloroethane] was incubated in soil under aerobic and anaerobic conditions. Primary degradation of methoxychlor occurred under anaerobic conditions, but not under aerobic conditions, after 3 months of incubation. Analysis of soil extracts, using gas chromatography, demonstrated that only 10% of the compound remained at initial concentrations of 10 and 100 ppm (wt/wt) of methoxychlor. Evidence is presented that a dechlorination reaction was responsible for primary degradation of methoxychlor. Analysis of soils treated with 100 ppm of methoxychlor in the presence of 2% HgCl2 showed that 100% of the compound remained after 3 months, indicating that degradation in the unpoisoned flasks was biologically mediated. Methanogenic organisms, however, are probably not involved, as strong inhibition of methane production was observed in all soils treated with methoxychlor. During the 3-month incubation period, little or no evaluation of 14CO2 or 14CH4 occurred under either aerobic or anaerobic conditions. Cometabolic processes may be responsible for the extensive molecular changes which occurred with methoxychlor because the rate of its disappearance from soil was observed to level off after exhaustion of soil organic matter. After this incubation period, soils previously incubated under anaerobic conditions were converted to aerobic conditions. The rates of 14CO2 evolution from soils exposed to anaerobic and aerobic sequences of environments ranged from 10- to 70-fold greater than that observed for soils exposed solely to an aerobic environment.     

Very strong UV-A light temporally separates the photoinhibition of photosystem II into light-induced inactivation and repair

When organisms that perform oxygenic photosynthesis are exposed to strong visible or UV light, inactivation of photosystem II (PSII) occurs. However, such organisms are able rapidly to repair the photoinactivated PSII. The phenomenon of photoinactivation and repair is known as photoinhibition. Under normal laboratory conditions, the rate of repair is similar to or faster than the rate of photoinactivation, preventing the detailed analysis of photoinactivation and repair as separate processes. We report here that, using strong UV-A light from a laser, we were able to analyze separately the photoinactivation and repair of photosystem II in the cyanobacterium Synechocystis sp. PCC 6803. Very strong UV-A light at 364 nm and a photon flux density of 2600 micromol photons m(-2) s(-1) inactivated the oxygen-evolving machinery and the photochemical reaction center of PSII within 1 or 2 min before the first step in the repair process, namely, the degradation of the D1 protein, occurred. During subsequent incubation of cells in weak visible light, the activity of PSII recovered fully within 30 min and this process depended on protein synthesis. During subsequent incubation of cells in darkness for 60 min, the D1 protein of the photoinactivated PSII was degraded. Further incubation in weak visible light resulted in the rapid restoration of the activity of PSII. These observations suggest that very strong UV-A light is a useful tool for the analysis of the repair of PSII after photoinactivation.     

Role of methanogens and other bacteria in degradation of dimethyl sulfide and methanethiol in anoxic freshwater sediments

The roles of several trophic groups of organisms (methanogens and sulfate- and nitrate-reducing bacteria) in the microbial degradation of methanethiol (MT) and dimethyl sulfide (DMS) were studied in freshwater sediments. The incubation of DMS- and MT-amended slurries revealed that methanogens are the dominant DMS and MT utilizers in sulfate-poor freshwater systems. In sediment slurries, which were depleted of sulfate, 75 micromol of DMS was stoichiometrically converted into 112 micromol of methane. The addition of methanol or MT to DMS-degrading slurries at concentrations similar to that of DMS reduced DMS degradation rates. This indicates that the methanogens in freshwater sediments, which degrade DMS, are also consumers of methanol and MT. To verify whether a competition between sulfate-reducing and methanogenic bacteria for DMS or MT takes place in sulfate-rich freshwater systems, the effects of sulfate and inhibitors, like bromoethanesulfonic acid, molybdate, and tungstate, on the degradation of MT and DMS were studied. The results for these sulfate-rich and sulfate-amended slurry incubations clearly demonstrated that besides methanogens, sulfate-reducing bacteria take part in MT and DMS degradation in freshwater sediments, provided that sulfate is available. The possible involvement of an interspecies hydrogen transfer in these processes is discussed. In general, our study provides evidence for methanogenesis as a major sink for MT and DMS in freshwater sediments.     

Sulfate-Mediated Bacterial Population Shift in a Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)-Degrading Anaerobic Enrichment Culture

The effects of sulfate on the population dynamics of an anaerobic hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)-degrading consortium were studied using terminal restriction fragment length polymorphism (T-RFLP) analysis. One hundred percent of the initial RDX was degraded in the sulfate-amended culture within 3 days of incubation. In the sulfate-unamended cultures, 35% of the initial RDX remained after 3 days and 8% after 7 days of incubation. Based on the T-RFLP distribution of the community 16S rDNA genes, the microcosm consisted predominantly of two organisms, a Geobacter sp. (78%) and an Acetobacterium sp. (14%). However, in the presence of sulfate, both species decreased to less than 3% of the total population within 3 days and an unclassified Clostridiaceae became the dominant organism at 40% the total fragment distribution. This indicated the explosive-degrading consortium had greater diversity than initially perceived and rapidly adapted to a readily available electron acceptor, which in turn stimulated RDX degradation.     

Very strong UV-A light temporally separates the photoinhibition of photosystem II into light-induced inactivation and repair

When organisms that perform oxygenic photosynthesis are exposed to strong visible or UV light, inactivation of photosystem II (PSII) occurs. However, such organisms are able rapidly to repair the photoinactivated PSII. The phenomenon of photoinactivation and repair is known as photoinhibition. Under normal laboratory conditions, the rate of repair is similar to or faster than the rate of photoinactivation, preventing the detailed analysis of photoinactivation and repair as separate processes. We report here that, using strong UV-A light from a laser, we were able to analyze separately the photoinactivation and repair of photosystem II in the cyanobacterium Synechocystis sp. PCC 6803. Very strong UV-A light at 364 nm and a photon flux density of 2600 μmol photons m⁻² s⁻¹ inactivated the oxygen-evolving machinery and the photochemical reaction center of PSII within 1 or 2 min before the first step in the repair process, namely, the degradation of the D1 protein, occurred. During subsequent incubation of cells in weak visible light, the activity of PSII recovered fully within 30 min and this process depended on protein synthesis. During subsequent incubation of cells in darkness for 60 min, the D1 protein of the photoinactivated PSII was degraded. Further incubation in weak visible light resulted in the rapid restoration of the activity of PSII. These observations suggest that very strong UV-A light is a useful tool for the analysis of the repair of PSII after photoinactivation.     

The action of dilute aqueous NN-dimethylhydrazine on bacterial cell walls

1. Walls of certain Gram-positive bacteria dissolved on incubation with dilute aqueous NN-dimethylhydrazine in the presence of air, by a reaction that probably involves free radicals. 2. Under the conditions described, the soluble products from the peptidoglycan were almost all non-diffusible. After brief incubation of walls of some organisms with reagent, part of the peptidoglycan component was obtained as a high-molecular-weight gel, the viscosity of which was rapidly decreased by incubation with lysozyme. 3. The extent to which peptidoglycan dissolved varied with different organisms, depending possibly on the extent of cross-linking, but the nature of the bonds that were destroyed has not been established. 4. Teichoic acids and polysaccharides were solubilized by this treatment and could be isolated in high overall yield. 5. The procedure is valuable in the examination of the distribution of heteropolymers in walls, and has been used to show that the polysaccharide present in walls of Lactobacillus arabinosus 17-5 is phosphorylated and may account for 20% of the total phosphate of the wall.