Effect of butyric acid on physiologic activity of carbohydrate-oxidizing rhodococci]

Laboratory experiments showed that butyric acid not only fails to meet the trophic requirements of hydrocarbon-oxidizing microorganisms, but even specifically inhibits their assimilatory and dissimilatory activity. Therefore, butyric acid can be referred to as growth inhibitors. The combined mineralization of carbohydrates and hydrocarbons can be described as follows. Plants polymers are converted to monosugars by heterotrophic soil microorganisms. As the concentration of the monosugars grows and oxygen becomes deficient, the monosugars are no longer oxidized completely but are fermented. As a result, glucose transforms to butyric acid, which inhibits hydrocarbon-oxidizing bacteria. It is concluded that, to be efficient, the cleanup of oil-contaminated soils must include measures to intensify the mineralization of carbohydrates and to inhibit their fermentation.     

Hydrocarbon-oxidizing microorganisms in the waters of certain regions of the Western and Central Atlantic

The incidence of hydrocarbon-oxidizing microorganisms in water was determined by the method of plating on solid media. Vertical distribution of hydrocarbon-oxidizing microflora was different near the shore and in the open ocean; the incidence of the microorganisms was low in the surface water layer but increased at depths of 25 and 75 m in the open ocean in contrast to regions near the shore. Pure bacterial and fungal cultures were isolated and their properties were described. The cultures were grown in a liquid mineral medium with diesel fuel and 50 cultures out of 66 were found to be true hydrocarbon-oxidizing microorganisms surviving under the laboratory conditions. It was shown that bacteria and fungi have grown on tarballs collected from the surface of the ocean during their incubation at 30 degrees C.     

Ratio [13C]/[12C] as an index for express estimation of hydrocarbon-oxidizing potential of microbiota in soil polluted with crude oil

The hydrocarbon-oxidizing potential of soil microbiota and hydrocarbon-oxidizing microorganisms introduced into soil was studied based on the quantitative and isotopic characteristics of carbon in products formed in microbial degradation of oil hydrocarbons. Comparison of CO2 production rates in native soil and that polluted with crude oil showed the intensity of microbial mineralization of soil organic matter (SOM) in the presence of oil hydrocarbons to be higher as compared with non-polluted soil, that is, revealed a priming effect ofoil. The amount of carbon of newly synthesized organic products (cell biomass and exometabolites) due to consumed petroleum was shown to significantly exceed that of SOM consumed for production of CO2. The result of microbial processes in oil-polluted soil was found to be a potent release of carbon dioxide to the atmosphere.     

Effect of photosynthetic bacteria and compost on degradation of petroleum products in soil

Addition of diesel fuel and waste engine oil to soil was found to cause biostimulation of hydrocarbon-oxidizing microorganisms. Corynebacteria constitute a large group of hydrocarbon-oxidizing microorganisms. Addition of a liquid culture of photosynthetic bacteria to soil not only facilitates degradation of petroleum products, but also stimulates growth of hydrocarbon-oxidizing microorganisms. Combined addition of photosynthetic bacteria and compost to soil polluted with petroleum products causes even a more significant increase in the count of hydrocarbon-oxidizing bacteria and substantially increases the rate of pollutant degradation.     

Ratio [13C]/[12C] as an index for express estimation of hydrocarbon-oxidizing potential of microbiota in soil polluted with crude oil

The hydrocarbon-oxidizing potential of soil microbiota and hydrocarbon-oxidizing microorganisms introduced into soil was studied based on the quantitative and isotopic characteristics of carbon in products formed in microbial degradation of oil hydrocarbons. Comparison of CO₂ production rates in native soil and that polluted with crude oil showed the intensity of microbial mineralization of soil organic matter (SOM) in the presence of oil hydrocarbons to be higher as compared with non-polluted soil, that is, revealed a priming effect of oil. The amount of carbon of newly synthesized organic products (cell biomass and exometabolites) due to consumed petroleum was shown to significantly exceed that of SOM consumed for production of CO₂. The result of microbial processes in oil-polluted soil was found to be a potent release of carbon dioxide to the atmosphere.     

Effects of butyric and acetic acids on acetone-butanol formation by Clostridium acetobutylicum

The actions of butyric and acetic acids on acetone-butanol fermentation are investigated. Production of butyric and acetic acids are controlled by the extracellular concentrations of both acids: acetic acid added to the medium inhibits its own formation but has no effect on butyric acid formation, and added butyric acid inhibits its own formation but not that of acetic acid. The ratio of end metabolites depends upon acetic and butyric acid quantities excreted during the fermentation. In contrast to acetic acid, which specifically increases acetone formation, butyric acid increases both acetone and butanol formations. Acetate and butyrate kinase activities were also examined. Both increase at the start of fermentation and decrease when solvents appear in the medium. Coenzyme A transferase activity is weak in the acidogenic phase and markedly increases in the solvent phase. Acetic and butyric acids appear to be co-substrates. On the basis of these results, a mechanism of acetic and butyric acid pathways, coupled to solvent formation by C. acetobutylicum glucose fermentation is proposed.     

Effect of Photosynthetic Bacteria and Compost on Degradation of Petroleum Products in Soil

Addition of diesel fuel and waste engine oil to soil was found to stimulate hydrocarbon-oxidizing microorganisms. Corynebacteria constitute a large group of hydrocarbon-oxidizing microorganisms. Addition of a liquid culture of photosynthetic bacteria to soil facilitates degradation of petroleum products and also stimulates growth of hydrocarbon-oxidizing microorganisms. Combined addition of photosynthetic bacteria and compost to soil polluted with petroleum products produces a greater increase in the number of hydrocarbon-oxidizing bacteria and substantially augments the rate of pollutant degradation.     

酪丁酸梭菌代谢工程菌的构建及其发酵特性

酪丁酸梭菌Clostridium tyrobutyricum可以利用葡萄糖、木糖、纤维二糖、阿拉伯糖等多种底物进行产酸发酵,主要发酵产物为丁酸和乙酸,是一种适合于木质纤维素同步糖化发酵生产丁酸的菌种。将酪丁酸梭菌乙酸发酵关键基因取代为丁酸发酵关键基因来构建突变株,可使突变株丁酸发酵量增多,乙酸发酵量减少。分别获得来源于丙酮丁醇梭菌的丁酸代谢关键酶基因——乙酰乙酰辅酶A转移酶基因(thl)、来源于酪丁酸梭菌本身的乙酸代谢关键酶基因片段——磷酸转乙酰基酶基因片段(pta)和来源于质粒pIMP1的红霉素抗性基因(em)。将它们与质粒pUC19相连构建为非复制性质粒pUC19-EPT。通过电转化将其导入酪丁酸梭菌中。利用红霉素抗性平板筛选获得转化子,通过PCR验证发现,获得的突变株染色体上pta被thl替换。在以葡萄糖为底物的发酵中,突变株丁酸得率为0.47,较野生型增大了34%,乙酸得率为0.05,较野生型下降了29%。     

Catalase activity of hydrocarbon-oxidizing bacteria

The dynamics of catalase activity of the hydrocarbon-oxidizing bacteria Gordona terrae, Rhodococcus rubropertinctus, and Rhodococcus erythropolis during petroleum product destruction has been studied. A direct relationship between decreasing catalase activity of hydrocarbon-oxidizing microorganisms and the intensity of petroleum product destruction has been established experimentally. The revealed dependence allows one to consider the catalase activity of bacteria as an indicator of the initial stage of petroleum product oxidation and may be used for choosing destructor strains to construct biopreparations suitable for natural ecosystem remediation.     

Sialic acids: fascinating sugars in higher animals and man

Sialic acids are acidic monosaccharides, which are among the most important molecules of higher animals, and occur in some microorganisms. They are bound to complex carbohydrates and occupy prominent positions, especially in cell membranes. Their structural diversity is high and, correspondingly, the mechanisms for their biosynthesis are complex. Sialic acid substituents strongly influence the activity of catabolic enzymes, in particular the sialidases, and thus the turnover rate of glycoconjugates. These sugars are involved in manifold cell functions. Due to the surface location of the acidic molecules they shield macromolecules and cells from enzymatic and immunological attacks. But they also represent recognition sites for various physiological receptors as well as for toxins and microorganisms, and thus allow their colonization. Many viruses use sialic acids for the infection of cells. As sialic acids also play a decisive role in tumor biology they prove to be rather versatile molecules that modulate cell biological events in a sensitive way. It is discussed that their evolvement may have stimulated evolution and rendered organisms less vulnerable to environmental attacks. However, disturbance of their metabolism may cause diseases.     

Isolation of hydrocarbon-oxidizing psychrophilic bacteria from oil-polluted soils

Microorganisms growing on a mineral medium with crude oil and its light fractions as only carbon and energy sources have been isolated from samples of oil-polluted soils collected in the Usa District (Komi Republic, Russia). For the first time, hydrocarbon-oxidizing psychrophilic bacteria of the genus Cytophaga have been found that are clearly capable of consuming crude oil hydrocarbons. A method for cultivating microorganisms on porous plastic is proposed. The data from the literature on the response of soil microbiota to oil pollution indicate that the pollution can activate or suppress the growth of various physiological groups of microorganisms [1]. Different soil and climatic conditions and pollution levels can give rise to different microbial cenoses, which include different associations and predominant microbial species.     

哺乳动物肠道微生物与碳水化合物的互作及其影响

肠道微生物具有调节宿主营养、免疫以及能量代谢等生理功能。饮食是影响哺乳动物的肠道微生物的一个重要因素。碳水化合物是哺乳动物食物能量的主要来源,因此研究肠道微生物与碳水化合物的代谢之间的关系及其影响具有重要意义。基于近年相关研究,本文从碳水化合物对肠道微生物组成的影响、肠道微生物对碳水化合物的代谢机制以及碳水化合物发酵产物短链脂肪酸对宿主的影响3个方面进行了综述。研究表明,肠道微生物可用于发酵的碳水化合物类型主要是抗性淀粉和非淀粉多糖;不同类型的碳水化合物会导致肠道菌群发生适应性变化;复杂多糖发酵产生的短链脂肪酸在调节宿主能量平衡和免疫应答方面发挥了重要作用。总结近年来相关研究,可加深对肠道菌群对宿主碳水化合物代谢贡献的理解,为哺乳动物机体健康状况的营养调控策略提供参考。     

Study of hydrocarbon oxidizing microorganisms from deep groundwater of the Puchezh-Katunki impact structure

The presence of viable hydrocarbon-oxidizing microorganisms has been shown in the under-ground waters exposed by the Vorotilovskaya deep well (the Puchezh-Katunki astrobleme, 75 km north of Nizhny Novgorod, 1900- and 3200-m deep) using the method of chromatography-mass spectrometry of specific biomarkers of the microbial cell wall and the classical methods of bacteriology. Several microbial species have been isolated in pure culture and identified. Two bacillary species, Bacillus pumilus KTB-2 and Bacillus subtilis KTB-4, were maintained in pure cultures at reinoculations. The effects of mineralization and aeration of the medium on the growth characteristics of Bacillus pumilus KTB-2 in batch culture have been studied.     

Rates of fermentative digestion in the howler monkey, Alouatta palliata (primates: ceboidea)

1. Caecal material of wild howler monkeys was analyzed by gas chromatography for evidence of fermentation activity and rates of production and absorption of volatile fatty acids. 2. Results showed a high rate of production of acetic acid and lesser production of propionic, butyric and isobutyric acids. The VFA content of the blood was increase in passage through the caecal vascular system. 3. We estimate that howler monkeys may obtain as much as 31% of their required daily energy from fermentation end products. 4. Energy rich fatty acids may be of particular importance to howlers when they are living on diets high in leaves, which have high cell wall contents and low contents of nonstructural carbohydrates.     

Construction of a model of the human proximal colon

The objective of the present study was to construct a system that re-creates the conditions of fermentation and absorption of the human proximal colon. The model was constructed using a glass tube with an internal dialysis membrane tube. The food substrate was fed into the dialysis membrane three times a day simulating a typical human feeding. The substrate contained 58% carbohydrates, 35% proteins, 3% fiber, 3% starch, and 1% lipids on dry weight base, with 90% moisture. The inoculum was a fecal culture propagated in TSB. The intestinal absorption was simulated using a polyethylene glycol (PEG) solution running continuously outside the dialysis membrane. All microorganisms increased their counts after inoculation, and reached higher counts generally after substrate feed. The most important short chain fatty acids (SCFA: acetic, propionic and butyric acids) were analyzed, and their concentrations inside and outside the membrane were significantly different due to the extraction efficiency of the PEG solution. The greatest production occurred at 48 h. SCFA ratios showed that at the beginning, acetate was the predominant compound, but after 12 h the proportion of butyrate increased and the acetate was decreased. This SCFA production pattern is similar to that reported for the proximal colon in live systems. Continuous operation of the colon model for 48 h was enough to reveal the development of microorganisms and SCFA production. This model reproduced the conditions of the human proximal colon adequately and can be used to study the development of colonic microbiota.     

Victor Ginsburg's influence on my research of the role of sialic acids in biological recognition

Sialic acids are monosaccharides with relatively strong acidity which belong to the most important molecules of higher animals and also occur in some microorganisms. They are bound to complex carbohydrates and occupy prominent positions, especially in cell membranes. Their structural diversity is high and, correspondingly, the mechanisms for their biosynthesis complex. Sialic acids are involved in a great number of cell functions. Due to their cell surface location these acidic molecules shield macromolecules and cells from enzymatic and immunological attacks and thus contribute to innate immunity. In contrast to this masking role, enabling, for example, blood cells and serum glycoproteins a longer life-time, sialic acids also represent recognition sites for various physiological receptors, such as the selectins and siglecs, as well as for toxins and microorganisms and thus allow their colonization. The recognition function of sialic acids can again be masked by O-acetylation, which modifies the interaction with receptors. Many viruses use sialic acids for the infection of cells. As sialic acids play also a decisive role in tumor biology, they prove to be rather versatile molecules that modulate biological and pathological cellular events in a sensitive way. Thus, they are most prominent representatives of mediators of molecular and cellular recognition.     

Rates of dissolution and biodegradation of water-insoluble organic compounds

We conducted a study of the relationship between the dissolution rates of organic compounds that are sparingly soluble in water and the biodegradation of these compounds by mixed cultures of bacteria. The rates of dissolution of naphthalene and 4-chlorobiphenyl were directly related to their surface areas. The bacteria caused a decline in the concentration of the soluble substrate. The rate of bacterial growth fell abruptly when 4-chlorobiphenyl or naphthalene was no longer detectable in solution. The population continued to increase in media with different surface areas of insoluble 4-chlorobiphenyl, but the final counts were higher in media in which the surface areas of the substrate were larger. The rates of dissolution of palmitic acid, octadecane, di(2-ethylhexyl) phthalate, and 1-naphthyl N-methylcarbamate were determined in the absence of microorganisms. A mixed culture of microorganisms mineralized palmitic acid, di(2-ethylhexyl) phthalate, and Sevin (1-naphthyl N-methylcarbamate) at a logarithmic rate, but octadecane mineralization was linear. The rates of mineralization at the end of the active phase of the biodegradation were lower than the rate of dissolution of palmitic acid but higher than the rate of dissolution of octadecane in the uninoculated medium. We suggest that spontaneous dissolution rates are only one of the factors that govern the rates of biodegradation.     

The effect of calcium and sodium hydroxides and of sodium acrylate on the fermentation and digestibility in vitro of ensiled whole-crop wheat and barley harvested at different stages of maturity

Whole-crop wheat and barley were each harvested at the soft-, medium- and hard-dough stages of grain development. Material from each harvest was ensiled in polythene bag silos without additive or after the addition of calcium hydroxide, sodium hydroxide or sodium acrylate at 50, 50 and 12.5 g kg_?1 of the crop dry matter (DM), respectively. All silages were opened after 60 days.With advancing maturity there was an increase in the content of DM, starch and insoluble-nitrogen, but a reduction in water-soluble carbohydrates (WSC) and ash.When crops were ensiled without additives, only medium-dough barley fermented to give butyric acid. However, the addition of calcium hydroxide to crops of low DM (soft-dough) and medium DM (medium-dough) promoted the activity of clostridial bacteria giving rise to the production of butyric acid, but this did not occur with crops of high DM (hard-dough). Sodium hydroxide gave rise to butyric acid only at low DM, and to restricted fermentation at high DM content. Sodium acrylate restricted fermentation and prevented butyric acid production in all silages.Ensiling led to an average reduction of 5 percentage units in the digestible organic matter (DOM) of the control silages compared to that of the crops. Addition of calcium hydroxide and sodium acrylate gave values similar to the control silages. Only sodium hydroxide consistently increased DOM, the effect becoming more marked as the crops matured. The increases over the control silages were 10, 18 and 26 units for wheat and 15, 21 and 20 units for barley at low, medium and high DM, respectively.     

Rates of dissolution and biodegradation of water-insoluble organic compounds.

We conducted a study of the relationship between the dissolution rates of organic compounds that are sparingly soluble in water and the biodegradation of these compounds by mixed cultures of bacteria. The rates of dissolution of naphthalene and 4-chlorobiphenyl were directly related to their surface areas. The bacteria caused a decline in the concentration of the soluble substrate. The rate of bacterial growth fell abruptly when 4-chlorobiphenyl or naphthalene was no longer detectable in solution. The population continued to increase in media with different surface areas of insoluble 4-chlorobiphenyl, but the final counts were higher in media in which the surface areas of the substrate were larger. The rates of dissolution of palmitic acid, octadecane, di(2-ethylhexyl) phthalate, and 1-naphthyl N-methylcarbamate were determined in the absence of microorganisms. A mixed culture of microorganisms mineralized palmitic acid, di(2-ethylhexyl) phthalate, and Sevin (1-naphthyl N-methylcarbamate) at a logarithmic rate, but octadecane mineralization was linear. The rates of mineralization at the end of the active phase of the biodegradation were lower than the rate of dissolution of palmitic acid but higher than the rate of dissolution of octadecane in the uninoculated medium. We suggest that spontaneous dissolution rates are only one of the factors that govern the rates of biodegradation.     

Effect of Short-Chain Fatty Acids and Soil Atmosphere on Tylenchorhynchus spp.

Short-chain fatty acids can be produced under anaerobic conditions by fermentative soil microbes and have nematicidal properties. We evaluated the effects of butyric and propionic acids on death and recovery of stunt nematodes (Tylenchorhynchus spp.), a common parasite of turfgrass. Nematodes in a sand-soil mix (80:20) were treated with butyric or propionic acid and incubated under air or N₂ for 7 days at 25 °C. Amendment of soil with 0.1 and 1.0 µmol (8.8 and 88 µg) butyric acid/g soil or 1.0 µmol (74 µg) propionic acid/g soil resulted in the death of all nematodes. The composition of the soil atmosphere had no effect on the nematicidal activity of the acids. Addition of hydrochloric acid to adjust soil pH to 4.4 and 3.5 resulted in nematode mortality relative to controls (41% to 86%) but to a lesser degree than short-chain fatty acids at the same pH. Nematodes did not recover after a 28-day period following addition of 10 µmol butyric acid/g soil under air or N₂. Carbon mineralization decreased during this period, whereas levels of inorganic N and microbial biomass-N remained constant. Short-chain fatty acids appear to be effective in killing Tylenchorhynchus spp. independent of atmospheric composition. Nematode mortality appears to be a function of the type and concentration of fatty acid and soil pH.