Laser printing of microbial systems: effect of absorbing metal film.

Recently, it was shown that laser-induced forward transfer (LIFT) technology and the laser engineering of microbial systems (LEMS) technique (based on LIFT method) are effective for isolation of micro-organisms from different complex substrates. These techniques frequently utilize Au as an absorbing layer material. The purpose of this study was to investigate the influence of absorbing film materials (Au, Ti and Cr) on the effectiveness of laser printing of micro-organisms to improve LEMS and LIFT techniques. It was shown that application of Ti and Cr absorbing layers activates bacterial growth after laser printing and is significantly more effective in comparison to Au films, which actually show a suppressing effect on bacterial cells. Results of this study can be applied for LEMS and LIFT protocols for improving bacterial isolation and microbial growth. SIGNIFICANCE AND IMPACT OF THE STUDY: Laser-induced forward transfer technique (LIFT) is currently used for printing of micro-organisms and in biosensor techniques, for single-cell isolation, and for culturing of micro-organisms from complex substrates. We have studied the influence of absorbing film materials (Au, Ti and Cr) on the effectiveness laser printing of micro-organisms. It was shown that application of Ti and Cr absorbing layers activates bacterial growth and is more effective in LIFT compared to Au films, which actually have a suppressive effect on bacteria cells. The results can improve LIFT protocols for bacteria isolation and culturing of microbial systems.

[Diversity and viability of prokaryotes in primitive soils of the larsemann oasis (East Antarctica)].

The diversity and viability of prokaryotic communities in the primitive organomineral soils of East Antarctica have been studied; it has been shown that the total number of bacteria is smaller than and the viability of bacteria is similar to that in soils of the temperate zone. The prokaryotic communities are characterized by the occurrence of a major part of cells in filterable forms, which is higher than the analogous parameter for the temperate soils. The method of fluorescence in situ hybridization (FISH) revealed that the distribution of the main taxons is similar to that in the temperate soils: the portion of the domain Archaea is smaller than that of the domain Bacteria; the total content of Gram-negative bacteria (the phyla Proteobacteria, Acidobacteria, and Planctomycetes) is higher than that of Gram-positive bacteria (Actinobacteria). Within the phylum Proteobacteria, a significant variation of three proteobacterial classes has been noted along the profiles of the soils studied.

[Number, viability, and diversity of the filterable forms of prokaryotes in sphagnous high-moor peat].

The number, potential viability, and taxonomic diversity (at the level of phylum) of the filterable forms of prokaryotes (FFP) are estimated in the main genetic horizons of high-moor peat. It was shown that the number of FFP reached 500 million cells in 1 g, i.e., up to 5% of the general size bacteria. The portion of viable cells among FFP (93-98%) was higher than that for the general size bacteria (60-68%). FISH-analysis (fluorescence in situ hybridization) showed that FFP contained the same phylogenetic groups as the population of general size bacteria (domain Archea and phylum Actinobacteria, Cytophaga, and Proteobacteria of the domain Bacteria).

[Bacterial complexes of the fruiting bodies and hyphosphere of certain basidiomycetes].

The surface and internal tissues of the fruiting bodies of basidiomycetes were shown to be specific bacterial habitats characterized by varying diversity and structure of bacterial complexes. On the surface of fruiting bodies, gram-negative bacteria of the genera Pseudomonas, Xanthomonas, and Myxococcus prevailed, while in the internal tissues gram-positive bacteria of the genera Streptomyces, Bacillus, Arthrobacter, and Micrococcus were identified in addition. Bacterial complexes from the surface and inner tissues of the fruiting bodies of the studied basidiomycetes showed significant similarity to each other and differed from those from the hyphosphere and the reference soil. On the surface and in the internal tissues of the fruiting bodies, representatives of the genus Myxococcus were identified for the first time, which could indicate initial decay of the fruiting body.

[The quantity and structure of the saprotrophic bacterial complex of the mycorhizosphere and hyphosphere of symbiotrophic basidiomycetes].

The impact of symbiotrophic basidiomycetes on the abundance and structure of the soil saprotrophic bacterial complex of the mycorhizosphere and hyphosphere of 10 species of symbiotrophic basidiomycetes in natural conditions is studied. Compared to the reference soil, one can observe a significant increase in bacterial abundance in the mycirhizosphere and hyphosphere of basidiomycetes. The analysis of the taxonomical structure of bacterial complexes showed that Pseudomonas prevail in the mycorhyzosphere and Bacillus, in the rhizosphere and reference soil. Bacterial complexes of the hyphosphere and those in reference soil showed greater similarity to each other than either of them does to the mycorhizosphere. This fact implies the selective impact of the mycorhizosphere on soil bacteria.

[Definition of the physiological condition of bacteria in soil by means of luminescent dye L7012].

By means of dye L7012, the number and physiological condition (damage rate of membranes) of bacterial cells is defined. The results testify to considerable physiological heterogeneity of bacteria cells in soils. In fresh samples of soil, the percentage of intact cells reached 60-70%. Damaged membranes occurred in 30-40% of cells. The number of damaged cells dramatically increased downwards through the soil profile. Drying and freezing of soil samples considerably reduced the quantity of intact cells and increased the percentage of cells with damaged membranes; the number of intact cells was 10-20%. Treatment with biocide agents resulted in lysis of the majority of cells and cells injuries. However, some of the cells kept an intact cellular membrane, which testifies to the high stability of bacteria in soil. These data allow us to offer a method of staining a soil suspension with the use of luminescent dye L7012 with the quality of an express method that gives the chance to monitor the number and physiological condition of the bacterial complex of soils.

[Lignite microorganisms].

The first demonstration that samples of lignite at a depth of 10 m are considerably enriched in bacteria is reported. According to direct microscopy, the abundance of bacteria was about 10(7) cells/g. About 70% of cells had intact cell membranes and small size, which points to their anabiotic state. The fungal mycelium length was no more than 1 m. Lignite inoculation onto solid glucose-yeast-peptone medium allowed as to isolate bacteria of the genera Bacillus, Rhodococcus, Arthrobacter, Micrococcus, Spirillum, and Cytophaga. Representatives of the genera Penicillium and Trichoderma were identified on Czapek medium. Moistening of lignite powder increased the microbial respiration rate and microbial and fungal abundance but did not increase their generic diversity. This finding suggests that the studied microorganisms are autochthonous to lignite.

[Number and structure of actinomycetes complexes in the rhizosphere winter rye, oat and red clover].

The actinomycetes complexes in the rhizosphere of three agricultural plants by using the methods of luminescense microscopy and cup sowing were investigated. It was established, that concentration of prokaryotic biomass and biomass of actinomycetes mycelium in rhizosphere of plants is higher than in free from the radicals to soil. Rhizosphera of the oat (Avena sativa L.) and red clover (Trifolium pratense L.) is colonized by Streptomyces, Micromonospora and olygospore species. Dominante actinomycetes of winter rye (Secale cereale L.) are classified into the genera Micromonospora. It was shown that numbers and biomass of actinomycetes mycelium were fond to decreased, diversity of actinomycetes in contrast is increased in the series: "winter rye--oat--red clover". In connection with ecological safety the capability of increase with prokaryotes naturally disease suppressive soil and stability of plants to pathogen is discussed.

[Monitoring of microbial degraders in manned space stations].

Samples of microorganisms from the surface of constructions of Mir Space Station (Mir SS) were taken and examined after 13 years of operation. The following microorganisms were isolated and identified: 12 fungal species belonging to the genera Penicillium, Aspergillus, Cladosporium, and Aureobasidium; 3 yeast species belonging to the genera Debaryomyces, Candida, and Rhodotorula; and 4 bacterial species belonging to the genera Bacillus, Myxococcus, and Rhodococcus. The predominant species in all samples was Penicillium chrisogenum. It was shown that the fungi isolated could damage polymers and induce corrosion of aluminum-magnesium alloys. We commenced a study of microbial degraders on constructions of the Russian section of the International Space Station (RS ISS). Twenty-six species of fungi, bacteria, yeasts, and actinomycetes, known as active biodegraders, were identified in three sample sets taken at intervals. We founded a collection of microorganisms surviving throughout space flights. This collection can be used to test spacecraft production materials, in order to determine their resistance to biodegradation.

[Tolerance of soil bacterial complexes to salt shock]. / Ustoichivost' kompleksa pochvennykh bakterii k solevomu shoku.

Investigations showed that bacteria present in soil are resistant to one-day exposure to a saturated solution of ammonium nitrate and can well develop when transferred to laboratory nutrient media. The evaluated number of bacteria in NH4NO3-treated soil samples was nearly the same as in native soil samples, while was 1.5-2.5 times smaller in the former than in the latter case when microbial succession in the soil samples was initiated by wetting them. Bacteria (particularly gram-negative ones) occurring at the early stages of succession were the most sensitive to salt stress. Bacteria in soil were found to be much more resistant to salt stress than the same bacteria isolated in pure cultures.

[The growth-promoting effect of Beijerinckia and Clostridium sp. cultures on some agricultural crops]. / Stimuliatsiia rosta rastenii kul'turami Beijerinckia i Clostridium.

New strains of Beijerinckia mobilis and Clostridium sp. isolated from the pea rhizosphere were studied with respect to their promoting effect on the growth and development of some agricultural crops. Seed soaking in bacterial suspensions followed by the soil application of the suspensions or their application by means of foliar spraying was found to be the most efficient method of bacterization. The application of B. mobilis and Clostridium sp. cultures in combination with mineral fertilizers increased the crop production by 1.5-2.5 times. The study of the population dynamics of B. mobilis by the method of genetic marking showed that this bacterium quickly colonized the rhizoplane of plants and, therefore, had characteristics of an r-strategist. At the same time, Clostridium sp. was closer to K-strategists, since this bacterium slowly colonized the econiches studied. The introduction of the bacteria into soil did not affect the indigenous soil bacterial complex. The presence of Clostridium sp. slowed down the colonization of roots by the fungal mycelium. The possible mechanisms of the plant growth-promoting activity of B. mobilis and Clostridium sp. are discussed.

[Effect of butyric acid on physiologic activity of carbohydrate-oxidizing rhodococci]. / Vlianie maslianoi kisloty na fiziologicheskuiu aktivnost' uglevodorodokisliaiushchikh rodokokkov

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.

[Bacterial soil variety: evaluation of methods, possibilities, and prospects ]. / Bakterial'noe raznoobrazie pochv: otsenka metodov, vozmozhnostei, perspektiv.

The paper presents a comparative description of the modern molecular genetic and routine culture techniques for assessing microbial diversity in soils and gives analysis for the different results obtained by these two groups of methods. The necessity of the collaboration of soil scientists, microbiologists, and molecular biologists in integrating different research methods for a proper assessment of soil microbial diversity is discussed. The paramount importance of soil as the source and reserve of biodiversity on the Earth is emphasized.

[Effect of serotonin (5-hydroxytryptamine) on the growth and differentiation of microorganisms]. / Deistvie serotonina (5-oksitriptamina) na rost i differentsiatsiiu mikroorganizmov.

Serotonin (5-hydroxytryptamine), a neurotransmitter and social behavior factor in higher animals, accelerates culture growth and induces cell aggregation in Escherichia coli and Rhodospirillum rubrum at concentrations of 2 x 10(-7)-2 x 10(-5)M. In the myxobacterium Polyangium sp., 10(-6)-10(-5)M serotonin stimulates cell aggregation and myxospore formation. At concentrations over 20 microM, serotonin induces the opposite effect: it inhibits cell aggregation and microbial culture growth. Serotonin at these concentrations also inhibits the light-dependent membrane potential generation in Rsp. rubrum (the data were obtained by the method of penetrating ions). Therefore, the above effects can be due to the elimination of the transmembrane electrical gradient by serotonin. As for micromolar serotonin concentrations, their effects presumably result from the specific action of serotonin as an intercellular communication agent accelerating and possibly synchronizing the development of the cell population.