Characterization and Genomic Analysis of the Naphthalene-Degrading Delftia tsuruhatensis ULwDis3 Isolated from Seawater.

Strains of the genus Delftia are poorly studied microorganisms. In this work, the complete genome of the naphthalene-degrading Delftia tsuruhatensis strain ULwDis3 isolated from seawater of the Gulf of Finland of the Baltic Sea was assembled. For the first time, genes encoding naphthalene cleavage pathways via salicylate and gentisate were identified in a strain of the genus Delftia. The genes are part of one operon (nag genes). Three open reading frames (ORFs) were found in the genome of D. tsuruhatensis strain ULwDis3 that encode gentisate 1.2-dioxygenase. One of the ORFs is part of the nag operon. The physiological and biochemical characteristics of the strain ULwDis3 when cultured in mineral medium with naphthalene as the sole source of carbon and energy were also studied. It was found that after 22 h of growth, the strain stopped consuming naphthalene, and at the same time, naphthalene 1.2-dioxygenase and salicylate 5-hydroxylase activities were not detected. Later, a decrease in the number of living cells and the death of the culture were observed. Gentisate 1.2-dioxygenase activity was detected from the time of gentisate formation until culture death.

Playgrounds in City of Pushchino with Different Types of Coating as Reservoir of Antibiotic-Resistant Strains of Pseudomonas spp.

In this study, we investigated antibiotic-resistant microorganisms isolated by the direct plating method from 6 playgrounds in the city of Pushchino, Moscow Region, with different types of coating: sand, soil with sand, grass and a modern playground coating made of pressed rubber crumb. According to the results of the study, sand is the cleanest type of coating, both in terms of the total count of cultivated microorganisms (8 × 105/g of substrate) and in terms of the content of resistant strains. The most contaminated both in terms of the total count of cultivated microorganisms (1.2-1.9 × 109/g of substrate) and in terms of the content of antibiotic-resistant strains was the coating of pressed rubber crumb. We isolated 65 antibiotic-resistant strains of fluorescent pseudomonads. Nine Pseudomonas strains were found to contain antibiotic resistance plasmids (one belongs to P-1 incompatibility group, seven to IncP-7 and one to unidentified incompatibility group). For the first time, we discovered a conjugative plasmid pD4A-46 conferring tetracycline resistance and belonging to the P-7 incompatibility group. Taking into account the results obtained under this study, it can be recommended to periodically treat the crumb rubber coating with non-toxic antiseptics, i.e. hydrogen peroxide or chlorhexidine.

Distribution of Archaeal Communities along the Coast of the Gulf of Finland and Their Response to Oil Contamination.

The Baltic Sea is vulnerable to environmental changes. With the increasing shipping activities, the risk of oil spills remains high. Archaea are widely distributed in many environments. However, the distribution and the response of archaeal communities to oil contamination have rarely been investigated in brackish habitats. Hence, we conducted a survey to investigate the distribution, diversity, composition, and species interactions of indigenous archaeal communities at oil-contaminated sites along the coast of the Gulf of Finland (GoF) using high-throughput sequencing. Surface water and littoral sediment samples were collected at presumably oil-contaminated (oil distribution facilities) and clean sites along the coastline of the GoF in the winter 2015 and the summer 2016. Another three samples of open sea surface water were taken as offshore references. Of Archaea, Euryarchaeota dominated in the surface water and the littoral sediment of the coast of the GoF, followed by Crenarchaeota (including Thaumarchaeota, Thermoprotei, and Korarchaeota based on the Greengenes database used). The unclassified sequences accounted for 5.62% of the total archaeal sequences. Our study revealed a strong dependence of the archaeal community composition on environmental variables (e.g., salinity, pH, oil concentration, TOM, electrical conductivity, and total DNA concentration) in both littoral sediment and coastal water in the GoF. The composition of archaeal communities was season and ecosystem dependent. Archaea was highly diverse in the three ecosystems (littoral sediment, coastal water, and open sea water). Littoral sediment harbored the highest diversity of archaea. Oil was often detected in the littoral sediment but rarely detected in water at those presumably contaminated sites. Although the composition of archaeal community in the littoral sediment was sensitive to low-input oil contamination, the unchanged putative functional profiles and increased interconnectivity of the archaeal core species network plausibly revealed resilience and the potential for oil degradation. Halobacteriaceae and putative cytochrome P450 pathways were significantly enriched in the oil-contaminated littoral sediment. The archaeal taxa formed highly interconnected and interactive networks, in which Halobacteriaceae, Thermococcus, and methanogens were the main components, implying a potential relevant trophic connection between hydrocarbon degradation, methanogenesis, sulfate reduction, and/or fermentative growth.

The organization of naphthalene degradation genes in Pseudomonas putida strain AK5.

The Pseudomonas putida АК5 that was isolated from the slime pit of a Nizhnekamsk oil chemical factory can metabolize naphthalene via salicylate and gentisate. Catabolic genes are localized on non-conjugative IncP-7 plasmid pAK5 of about 115 kb in size. The "classical"nah-1 operon and the novel sgp-operon (salicylate-gentisate pathway) are both involved in naphthalene degradation by P. putida АК5, that was first described for Pseudomonas. The sgp-operon includes six open reading frames (ORFs) (sgpAIKGHB). The four ORFs code for the entire salicylate 5-hydroxylase - oxidoreductase component (sgpA), large and small subunits of the oxigenase component (sgpG and sgpH) and 2Fe-2S ferredoxin (sgpB). Genes for gentisate 1, 2-dioxygenase (sgpI) and fumarylpyruvate hydrolase (sgpK) are located in salicylate 5-hydroxylase genes clustering between sgpA and sgpG. The putative positive regulator for the sgp-operon (sgpR) was found upstream of the sgpA gene and oriented in the opposite direction from sgpA. The putative maleylacetoacetate isomerase gene is located apart, directly downstream from the sgp-operon. The sgp-operon organization and phylogenetic analysis of deduced amino acid sequences indicate that this operon has a mosaic structure according to the modular theory of the evolution of modern catabolic pathways.