Erwinia amylovora bacteriophages are of interest as fire blight control agents. This paper presents data on the biology and molecular genetic properties of 12 E. amylovora tailed bacteriophages. Genome sequences of seven of them were determined and the phages were identified as the representatives of Caudoviricetes; Vequintavirinae, Ounavirinae and Autographiviridae families. The bacteriophages studied were active against E. amylovora, Pantoea agglomerans and Pantoea ananatis strains. The myovirus Hena1 had the narrowest host range lysing 12

The composition of microbial communities and the rates of microbial processes in the water column of a meromictic trough in the Biofilter Bay, Kandalaksha Bay, White Sea were investigated in September 2020 and March 2021. The chemocline zone was located at the depths from 8 to 9 m. Sulfide was present in the monimolimnion, its concentration at the bottom reaching 25‒38 mg L–1 (0.7‒1.1 mmol). Conditions of the redox zone favored development of both anaerobic anoxygenic phototrophs and aerobic sulfur-oxidizing chemoautotrophs. A pinkish-brown bacterial plate was formed in this zone. Sequencing of the 16S rRNA gene fragments revealed predominance of green sulfur bacteria (GSB) Chlorobium phaeovibrioides. Aerobic sulfur-oxidizing bacteria Sulfurimonas sp. were the second most abundant group. Plating of chemocline samples on selective media resulted in massive formation of brown-colored Chlorobi colonies, while green GSB colonies were few. Both morphotypes were identified as Chlorobium phaeovibrioides. At the time of our study, purple sulfur bacteria (PSB) did not form a bacterial plate in the redox zone, although few PSB colonies were revealed. The PSB isolate was identified as Thiocapsa rosea. Members of this species are able to switch from photosynthesis to aerobic chemosynthesis and may compete for sulfide with sulfur-oxidizing chemo-autotrophs. We suggest that due to its openness the Biofilter Bay meromictic trough may act as a source for the propagation of anoxygenic phototrophic bacteria in the Kandalaksha Bay.

The causative agent of melioidosis, Burkholderia pseudomallei, as well as closely related nonpathogenic bacteria of the B. pseudomallei/thailandensis complex of species, are found in soils and water bodies in melioidosis-endemic areas which results in significant biological risks to agricultural workers in these regions. Bacteriophages related to the phiBp-AMP1 phage are the most common known group of B. pseudomallei/thailandensis viruses. The interaction of these bacteriophages with their hosts may be a key factor in the natural control of the B. pseudomallei population, which determines the dynamics of melioidosis infection in humans. In this study, we showed that frequently used herbicides (paraquat, atrazine, 2,4-D, ametrine, and copper dichloride) did not significantly affect the stability and infectivity of the AMP1 phage, while iron(II) salts, which are used as fertilizers, inactivated the phage even at concentrations of about 0.1 mM or lower. Moreover, the concentration of sodium chloride was critical for the infectivity of the AMP1 phage, both against B. thailandensis and against the pathogen B. pseudomallei. When the concentration of this salt in solution was less than 3 g/L, the phages ceased infecting the host cells. Therefore, soil salinity may thus be responsible for the mosaic pattern of B. pseudomallei population dynamics within a number of endemic regions, such as northeastern Thailand.

An Erratum to this paper has been published: https://doi.org/10.1134/S0026261722602238

Erwinia amylovora bacteriophages can be considered as potential agents for the control of fire blight. In present work bacteriophages Hena2, Roscha1, Dichka, Pixel, and VyarbaS, isolated in Belarus, are characterized. The ability of bacteriophages to multiply and inhibit the bacterial growth was studied. According to the OD600nm measurement data, infection with bacteriophages reduced the E. amylovora growth by 59 ± 9.7–90 ± 7.4 %, as well as the CFU/ml, on average, 40 ± 6.7– 163 ± 86.7 times. When the bacterial cultures of E. amylovora 1/79Sm was infected with bacteriophages, the frequency of the phage-resistant mutants incidence ranged from 3.2 × 10–3 ± 2.2 × 10–3 to 5.1 × 10–3 ± 4.3 × 10–3 %. Relatively high values of the lysis index of the E. amylovora bacterial culture were demonstrated for the studied bacteriophages. However, the presence of viable cells in phage lysates and the high frequency of the phage-resistant mutants incidence indicate the need to apply cocktails of bacteriophages for elimination of bacteria.

The viromes of the mammalian lower gut were shown to be heavily dominated by bacteriophages; however, only for humans were the composition and intervariability of the bacteriophage communities studied in depth. Here we present an ecogenomics survey of dsDNA bacteriophage diversity in the feces of horses (Equus caballus), comparing two groups of stabled horses, and a further group of feral horses that were isolated on an island. Our results indicate that the dsDNA viromes of the horse feces feature higher richness than in human viromes, with more even distribution of genotypes. No over-represented phage genotypes, such as CrAssphage-related viruses found in humans, were identified. Additionally, many bacteriophage genus-level clusters were found to be present in all three geographically isolated populations. The diversity of the horse intestinal bacteriophages is severely undersampled, and so consequently only a minor fraction of the phage contigs could be linked with the bacteriophage genomes. Our study indicates that bacteriophage ecological parameters in the intestinal ecosystems in horses and humans differ significantly, leading them to shape their corresponding viromes in different ways. Therefore, the diversity and structure of the intestinal virome in different animal species needs to be experimentally studied.

— 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 10 8 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.

Significant impact of Bp-AMP1-related bacteriophages on the population dynamics of Burkholderia pseudomallei in agroecosystems of the regions endemic for melioidosis has been repeatedly hypothesised in recent years. Temperature-dependent life cycle of these viruses may be responsible for modulation of the natural phage-mediated biocontrol, and thus it may contribute to the complexity of the seasonal dynamics of melioidosis observed. Refined data on Bp-AMP1 phage genome organization are a prerequisite for the ongoing research on infection physiology of this virus. In the present work, location of the physical ends of the virion-encapsidated phage DNA was determined, 389-bp long terminal repeats were revealed, and the annotation of the phage Bp-AMP1 genome sequence was revised.

A method is proposed for integral assessment of the propagation of microbial cells and phage particles during seasonal thawing of relic ice wedge layers. The results of field and laboratory investigation carried out in the upper part of permafrost exposure at Mamontova Gora (Yakutiya, Russia) are presented. Suspensions of yeast, bacteria, and two coliphages were introduced as biomarkers directly on the surface of thawing ice and in the meltwater flow. Microorganisms and phages were shown (a) to possess particular parameters of dissemination in the meltwater flow and (b) were able to move 132 m in 25–35 min with the stream water flow.