Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Applied Biochemistry and Microbiology (v.48, #4)
Combined biological hydrogen-producing systems: A review by D. N. Tekucheva; A. A. Tsygankov (pp. 319-337).
Possible ways for combining various biological processes of biohydrogen production are described. Some of these processes are being intensively studied now, whereas others are theoretically feasible, but have not been studied. A special focus is on the factors that influence the efficiency of coupled systems.
Isolation and functional characterization of lipase from the thermophilic alkali-tolerant bacterium Thermosyntropha lipolytica by V. M. Gumerov; A. V. Mardanov; P. M. Kolosov; N. V. Ravin (pp. 338-343).
As a result of sequencing the genome of the termophilic alkali-tolerant lipolytic bacterium Thermosyntropha lipolytica, the gene encoding a lipase secreted into the medium was identified. The recombinant enzyme was expressed in Escherichia coli. It was isolated, purified, and functionally characterized. The lipase exhibited hydrolytic activity toward para-nitrophenyl esters of various chain lengths, as well as triglycerides, including vegetable oils. The optimal reaction conditions were achieved at temperatures from 70 to 80°C and pH 8.0. This new thermostable lipase may be a promising biocatalyst for organic synthesis; it may find application in the food and detergent industry and biodiesel production.
1-Butanol synthesis by Escherichia coli cells through butyryl-CoA formation by heterologous enzymes of clostridia and native enzymes of fatty acid β-oxidation by A. Yu. Gulevich; A. Yu. Skorokhodova; A. A. Morzhakova; S. V. Antonova; A. V. Sukhozhenko; R. S. Shakulov; V. G. Debabov (pp. 344-349).
Anaerobic biosynthesis of 1-butanol from glucose is investigated in recombinant Escherichia coli strains which form butyryl-CoA using the heterologous enzyme complex of clostridia or as a result of a reversal in the action of native enzymes of the fatty acid β-oxidation pathway. It was revealed that when the basic pathways of acetic and lactic acid formation are inactivated due to deletions of the ackA, pta, poxB, and ldhA genes, the efficiency of butyryl-CoA biosynthesis and its reduced product, i.e., 1-butanol, by two types of recombinant stains is comparable. The limiting factor for 1-butanol production by the obtained strains is the low substrate specificity of the basic CoA-dependent alcohol/aldehyde dehydrogenase AdhE from E. coli to butyryl-CoA. It was concluded that, in order to construct an efficient 1-butanol producer based on a model strain synthesizing butyryl-CoA as a result of reversed action of fatty acid β-oxidation enzymes, it is necessary to provide intensive formation of acetyl-CoA and enhanced activity of alternative alcohol and aldehyde dehydrogenases in the cells of a strain.
Putative down-stream signaling molecule of GTPase in Porphyromonas gingivalis by M. -J. Chun; K. -J. Park; S. -H. Ohk (pp. 350-354).
Porphyromonas gingivalis is a strict anaerobic bacterium mainly responsible for periodontal disease in oral cavity. Putative GTPase gene (pgp) of this bacterium was cloned and its recombinant protein (rPGP) was produced in Escherichia coli. Based on the amino acid sequence of SGP that is a GTP-binding protein of Streptococcus mutans, putative GTPase amino acid sequence was deduced in the data base of genome sequences of Porphyromonas gingivalis. A 900-bp PCR fragment was amplified with P. gingivalis genomic DNA as a template and cloned into E. coli JM109. Then pgp was transferred into pQE-30 expression vector to make pQE-PGP for production of rPGP. This protein was produced and purified by Ni-NTA affinity column chromatography. Anti-PGP antibody was also produced in Sprague Dawley rats. Using Westernblot analysis with this antibody, it was confirmed that the rPGP produced in E. coli was identical to that of donor strain. Furthermore, by Southernblot analysis it was revealed that the pgp was originated from P. gingivalis. By immunoprecipitation with anti-PGP antibody and N-terminal amino acid sequence analysis it was found that PGP was able to bind to acetate kinase, which was reported to be a secondary signaling molecule in anaerobic microorganisms. Therefore, these results imply that P. gingivalis produces putative GTPase and this protein might play a potential role in signaling pathway in oral biofilm formation.
Role of allelopathic compounds in the regulation and development of legume-rhizobial symbiosis by L. E. Makarova; V. I. Smirnov; L. V. Klyba; I. G. Petrova; L. V. Dudareva (pp. 355-362).
It was discovered that aromatic compounds isolated from root exudates of three legume species (Pisum sativum L., Vicia faba L. var. major Hartz, and Glycine max L. MERR) and identified as N-phenyl-2-naphthyl amine, dibutyl, and dioctyl esters of ortho-phthalic acid, which are known to work as negative allelopathic substances, are involved in the regulation of legume-rhizobial symbiosis formation after the inoculation of roots with rhizobia under unfavorable conditions for symbiosis.
Biofilm, ice recrystallization inhibition and freeze-thaw protection in an epiphyte community by Z. Wu; F. W. K. Kan; Y. -M. She; V. K. Walker (pp. 363-370).
Microbial communities found on the surface of overwintering plants may be exposed to low temperatures as well as multiple freeze-thaw events. To explore the adaptive mechanisms of these epiphytes, with the objective of identifying products for freeze-protection, enrichment libraries were made from frost-exposed leaves. Of 15 identified bacteria from 60 individual clones, approximately half had ice-association activities, with the great majority showing high freeze-thaw resistance. Isolates with ice nucleation activity and ice recrystallization inhibition activity were recovered. Of the latter, two (Erwinia billingiae J10, and Sphingobacterium kitahiroshimense Y2) showed culture and electron microscopic evidence of motility and/or biofilm production. Mass spectrometric characterization of the E. billingiae extracellular polymeric substance (EPS) identified the major proteins as 35 kDa outer membrane protein A and F, supporting its biofilm character. The addition of the EPS preparation increased the freeze-thaw survival of the more susceptible bacteria 1000-10000 times, and protection was at least partially dependent on the protein component.
Microbial activity in the landfill soil by M. Swiontek Brzezinska; A. Burkowska; M. Walczak (pp. 371-376).
The research objective was to determine the activity of microorganisms in the soil exposed to direct influence of a landfill, as well as in the soil beyond its influence. Fluorescein diacetate (FDA) hydrofytic activity and respiration in the soil were determined. The highest number of cultivated bacteria was recorded at the site located within the zone of direct influence exerted by the landfill, whereas the least amount was found at a distance of 1000 metres from the landfill. In contrast, the largest numbers of molds were observed in the soil at a distance of 1000 m from the headquarters of the landfill. The highest FDA hydrolytic activity and biological oxygen demand (BOD5) were recorded in the soil by the headquarters of the landfill, and the least parameters were revealed at a distance of 1000 m from the landfill. It was found a high correlation between the number of bacteria and FDA hydrolytic activity of soil and BOD5 in the north-eastern of the landfill. However, in the same place, there is a low correlation between the number of molds, and FDA hydrolytic activity of soil and BOD5.
Biogas production by microbial communities via decomposition of cellulose and food waste by E. A. Tsavkelova; M. A. Egorova; E. V. Petrova; A. I. Netrusov (pp. 377-384).
Several active microbial communities that form biogas via decomposition of cellulose and domestic food waste (DFW) were identified among 24 samples isolated from different natural and anthropogenic sources. The methane yield was 190–260 ml CH4/g from microbial communities grown on cellulose substrates, office paper, and cardboard at 37°C without preprocessing. Under mesophilic conditions, bioconversion of paper waste yields biogas with a methane content from 47 to 63%; however, the rate of biogas production was 1.5–2.0 times lower than under thermophilic conditions. When microbial communities were grown on DFW under thermophilic conditions, the most stable and effective of them produced 230–353 ml CH4/g, and the methane content in biogas was 54–58%. These results demonstrates the significance of our studies for the development of a technology for the biotransformation of paper waste into biogas and for the need of selection of microbial communities to improve the efficiency of the process.
Elimination of volatile compounds of leaf tobacco from air emissions using biofiltration by N. A. Zagustina; T. A. Misharina; A. A. Veprizky; V. G. Zhukov; A. O. Ruzhitsky; M. B. Terenina; N. I. Krikunova; A. K. Kulikova; V. O. Popov (pp. 385-395).
The composition of the volatile organic compounds (VOCs) of various leaf tobacco brands and their blends has been studied. The differences in the content of nicotine, solanone, tetramethyl hexadecenol, megastigmatrienones, and other compounds, determining the specific tobacco smell, have been revealed. A microbial consortium, which is able to deodorize simulated tobacco emissions and decompose nicotine, has been formed by long-term adaptation to the VOCs of tobacco leaves in a laboratory reactor, functioning as a trickle-bed biofilter. Such a biofilter eliminates 90% of the basic toxic compound (nicotine) and odor-active compounds; the filtration efficiency does not change for tobacco brands with different VOC concentrations or in the presence of foreign substances. The main strains, isolated from the formed consortium and participating in the nicotine decomposition process, belong to the genera Pseudomonas, Bacillus, and Rhodococcus. An examination of the biofilter trickling fluid has shown full decomposition of nicotine and odor-active VOCs. The compounds, revealed in the trickling fluid, did not have any odor and were nontoxic. The obtained results make it possible to conduct scaling of the biofiltration process to eliminate odor from air emissions in the tobacco industry.
EDTA degradation by cells of Chelativorans oligotrophicus immobilized on a biofilter by E. N. Kaparullina; N. V. Doronina; V. A. Ezhov; Yu. A. Trotsenko (pp. 396-400).
A biofilter based on light expanded clay aggregate (LECA) and cells of the obligate ethylenediamine tetraacetate (EDTA) destructor Chelativorans oligotrophicus LPM-4 has been developed. The culture steadily maintained a high level of EDTA monooxygenase activity of 180–200 nmol/min/mg of protein during three months. EDTA was converted completely or by 80% at initial concentrations of 0.5–0.7 or 2.0 g/l, respectively, in a 2-dm2 biofilter at a flow rate of 20 ml/h.
Extracellular β-D-glucosidase of the Penicillium canescens marine fungus by Yu. V. Dubrovskaya; V. V. Sova; N. N. Slinkina; S. D. Anastyuk; M. V. Pivkin; T. N. Zvyagintseva (pp. 401-408).
Extracellular β-D-glucosidase was isolated in a homogeneous state from the Penicillium canescens marine fungus. According to SDS-electrophoresis, the molecular weight of the enzyme was 64 kDa and the maximal activity was observed at pH 5.2 and 70°C. Glucosidase catalyzed the hydrolysis of β-glycosidic bonds both in glycosides and in glucose disaccharides and had transglycosylation activity. The enzyme can be used for the deglycosylation of natural glycosides and in enzymatic synthesis of new carbohydrate—containing compounds.
Fusant Trichoderma HF9 with enhanced extracellular chitinase and protein content by N. Balasubramanian; V. Thamil Priya; S. Gomathinayagam; D. Lalithakumari (pp. 409-415).
Strain improvement was carried out to obtain higher chitinase and protein by inter-specific protoplast fusion between Trichoderma harzianum and Trichoderma viride. Fusant HF9 and parental strains of Trichoderma were compared for chitinase and protein production. 1% of glucose, sucrose and fungal cell wall (Rhizoctonia solani), were used as carbon source for cultivation of Trichoderma and fungal cell wall was the best to induce chitinase and protein. Usage of 0.5% colloidal chitin for the fungal growth under aerated conditions at pH 6.5 and 28°C led to higher chitinase and protein production. In these conditions fusant Trichoderma HF9 in comparison with parent strains had 3-, 2.5- and 1.5-fold increase of total chitinase, specific chitinase and protein, respectively. SDS-PAGE analysis revealed that it had 9 major protein bands with up-regulation compared to parent strains. Amino acid analysis showed that protein of culture filtrate of T. harzianum, T. viride and fusant Trichoderma HF9 had 8, 6 and 10 amino acids, respectively. The results obtained suggested that fusant HF9 could be an integration of T. harzianum and T. viride through protoplast fusion.
Purification of the chimeric protein alburon16 from a culture medium of the yeast Pichia pastoris by A. V. Karabel’skii; M. V. Padkina (pp. 416-420).
Conditions have been created for the isolation of the chimeric protein Alburon16 (human albumin-interferon-α 16) from a culture medium of the yeast Pichia pastoris, under which there is no aggregation of the protein and its biological activity is maintained. The proposed scheme can be used for the isolation and purification of a chimeric protein in laboratory conditions. The obtained results may be useful for improving the purification methods of various recombinant proteins synthesized and secreted by the yeast P. pastoris.