Microbiology

Effect of Trisporoids on Lipogenesis of the T (–) Strain of a Mycelial Fungus Blakeslea trispora

A New Ensifer adhaerens Strain M1 is Capable of Transformation of Perfluorocarboxylic Acids

Sulfur-Oxidizing Bacteria Dominate in the Water from a Flooded Coal Mine Shaft in Kuzbass

Application of Morphological and Molecular Systematics for Identification of Green Microalgae of the Genus Chlorococcum and Some Closely Related Taxa Abstract— Polyphyletic nature of three genera of green microalgae, Chlorococcum, Deasonia, and Neospongiococcum, was confirmed. Some Chlorococcum species, together with the type species C. infusionum, formed a true clade Chlorococcum within the macroclade Moewusinia. Its members were characterized by extremely long ITS2 regions with unusual secondary structure. Other species were found to belong to the Stephanosphaeriniamacroclade, and should be reclassified accordingly. The research of authentic strains resulted in revised and enhanced morphological descriptions of N. gelatinosum, C. diplobionticum, C. isabeliense, and C. sphacosum. Proposals on taxonomic revision are based on morphological similarity, 18S rRNA distances, presence of compensatory base changes in ITS2 conserved regions, differences in the secondary structure of the spacer, and differences of the helix III conserved motif.

Quenchers Protect BChl850 from Action of Singlet Oxygen in the Membranes of a Sulfur Photosynthetic Bacterium Allochromatium vinosum Strain MSU Abstract— The effect of singlet oxygen was studied in the system of Allochromatium (Alc.) vinosum MSU membranes, rose bengal, and light (547−600nm) with and without a quencher. In the system without a quencher, bleaching of the BChl850 band of the LH2 light-harvesting complex was observed and an absorption peak emerged at 698 nm, which belonged to the oxidized product, 3-acetyl-chlorophyll. The efficiency of five quenchers of singlet oxygen for neutralization of the effect of singlet oxygen on bacteriochlorophyll in the light-harvesting complexes of the membranes Alc. vinosum MSU was studied: sodium ascorbate, histidine, imidazole, trolox, and sodium azide. All of them, with the exception of sodium azide, neutralized successively the effect of singlet oxygen.

The Efficacy of Nano Silver Sulfadiazine and Nano Benzalkonium Chloride on Heterotrophic Biofilms Abstract Silver sulfadiazine and benzalkonium chloride are biocidal agents known to be effective against microorganisms. Although planktonic cells are easily affected by these agents, bacteria in the biofilm layer are more resistant to the same chemicals. Agents fixed on nanoparticles are reported to have higher antimicrobial activity against biofilm bacteria. The effects of nanotechnological disinfectants on biofilm bacteria vary with dose and time. Also, the type of surface on which these disinfectants are sprayed also changes their activity. The aim of the study was to investigate the efficacy of nano silver sulfadiazine and nano benzalkonium on mature heterotrophic biofilm bacteria. Stainless steel coupons were sprayed with nano benzalkonium chloride and nano silver sulfadiazine and were air-dried to cure for 24 hours, then the coupons were placed into the biofilm reactor. Bacterial counts in the biofilm layer were compared at monthly intervals against control coupons. Heterotrophic biofilms allowed to form naturally for 4 months, were analyzed by microbiological culture methods. The number of live and dead microorganisms were determined by DAPI–CTC staining using epifluorescence microscope. After the test periods, microbial culture and DAPI–CTC (live/dead) results were found significantly lower on disinfectant covered coupons. Furthermore, nano benzalkonium chloride was found to be significantly more effective against biofilm bacteria than nano silver sulfadiazine. The results were examined in order to observe biofilm formation on the surfaces covered with nano benzalkonium chloride and nano silver sulfadiazine compounds, to evaluate their use in industrial and clinical fields as effective disinfectants. Because these disinfectants are frequently used in industrial or clinical environments, results have made an important contribution to the manufacturers to focus on final version of the product.

Seasonal Variations in the Structure of an Anoxygenic Phototrophic Bacterial Community from the Meromictic Lake Trekhtsvetnoe (Kandalaksha Bay, White Sea) Abstract— The community of anoxygenic phototrophic bacteria (APB) from the water column of the meromictic Lake Trekhtsvetnoe (Kandalaksha Bay, White Sea, Russia) was studied in March 2012 and 2013 and in September 2013 and 2014. The community structure below the chemocline was shown to restore during three years after partial mixing resulting from seawater admixture into the lake in autumn 2011; a dense layer (at least 108 cells mL–1) of green-colored (g/c) sulfur bacteria (GSB) was formed. During winter, development of low numbers of brown colored (b/c) GSB was observed in the upper layer of green water. During summer seasons, b/c GSB were found to be located in the oxic zone above the green water layer, which was unusual for these organisms. The APB community was found to contain purple bacteria. Four APB strains were isolated from the upper part of the sulfide zone. The b/c and g/c GSB strains were phylogenetically close to each other and to the type species Chlorobium phaeovibrioides DSM 265 (99% similarity gene sequences). One strain of purple bacteria was phylogenetically related to the brackish sulfur bacteria Thiocapsa marina, while the other was related to freshwater bacteria Rhodopseudomonas palustris. The strains of sulfur bacteria were phylogenetically close to the chemocline bacteria from the stratified Lake Kislo-Sladkoe, also located in the coastal zone of the Kandalaksha Bay, White Sea.

Quantitative Methods for Single-Cell Analysis of Microorganisms Abstract—Modern ideas about the world of microorganisms have been developed mainly due to the studies at the population level. Such an approach was justified by the need to overcome the limitations in the sensitivity of the physicochemical, molecular biological, and genetic methods used. The potential differences between individual cells were therefore leveled, the properties of all cells were averaged, and the obtained data characterized the studied microbial populations as a whole. Over time, some analytical methods have been improved to such an extent that the prospect of quantitatively exploring many physicochemical and morphological properties of individual microbial cells has been opened up. This allowed taking a new approach to solving a number of problems, including the heterogeneity of microbial populations, the nature of the microorganisms unculturable in laboratory conditions and of persistent states, the development of biofilms, the interaction of microorganisms with plant and animal cells, the relationship of structure and function in metabolism, and a number of others. This review briefly describes the main methods of quantitative analysis of single bacterial and yeast cells at the cellular and subcellular levels and presents examples of their use according to the literature for the last fifteen years.

Effect of Constitutive Expression of the rapA1 Gene on Formation of Bacterial Biofilms and Growth-Stimulating Activity of Rhizobia Abstract— In order to investigate the effect of the RapA1 protein on growth-stimulating activity, biofilm formation, and root colonization by rhizobia, strains Rhizobium leguminosarum Pvu5, VSy12, Thy2, TPr4 and R. galegae 0702 were transformed with the pJN105TurboRapA1GFP vector, providing for constitutive expression of the rapA1 and gfp genes. Constitutive expression of the rapA1 gene was shown to result in more efficient biofilm formation on inert surfaces and to promote microcolony formation on plant root surfaces. Analysis of auxin production by wild and transformed strains revealed decreased auxin synthesis in all transformed strains, except for R. leguminosarum Thy2. Growth-stimulating activity of the wild and transformed strains did not correlate with the amount of auxins produced in vitro.

Effect of Low-Frequency Pulsed Magnetic Field and Low-Level Laser Radiation on Oxidoreductase Activity and Growth of Fungi—Active Destructors of Polymer Materials Abstract— Effect of low-frequency pulsed magnetic field and of low-intensity laser radiation on mycelial fungi actively degrading various polymer materials was studied. These factors had a different effect on spores of fungi and mycelia. Irradiation could stimulate and suppress fungal growth. The studied physical factors had dose-dependent effects on activity of the extracellular fungal oxidoreductases (catalase and peroxidase); both increased and decreased enzymatic activities were observed.