RNA-Seq Virus Fraction in Lake Baikal and Treated Wastewaters

Abstract

In this study, we analyzed the transcriptomes of RNA and DNA viruses from the oligotrophic water of Lake Baikal and the effluent from wastewater treatment plants (WWTPs) discharged into the lake from the towns of Severobaikalsk and Slyudyanka located on the lake shores. Given the uniqueness and importance of Lake Baikal, the issues of biodiversity conservation and the monitoring of potential virological hazards to hydrobionts and humans are important. Wastewater treatment plants discharge treated effluent directly into the lake. In this context, the identification and monitoring of allochthonous microorganisms entering the lake play an important role. Using high-throughput sequencing methods, we found that dsDNA-containing viruses of the class Caudoviricetes were the most abundant in all samples, while Leviviricetes (ssRNA(+) viruses) dominated the treated water samples. RNA viruses of the families Nodaviridae, Tombusviridae, Dicitroviridae, Picobirnaviridae, Botourmiaviridae, Marnaviridae, Solemoviridae, and Endornavirida were found in the pelagic zone of three lake basins. Complete or nearly complete genomes of RNA viruses belonging to such families as Dicistroviridae, Marnaviridae, Blumeviridae, Virgaviridae, Solspiviridae, Nodaviridae, and Fiersviridae and the unassigned genus Chimpavirus, as well as unclassified picorna-like viruses, were identified. In general, the data of sanitary/microbiological and genetic analyses showed that WWTPs inadequately purify the discharged water, but, at the same time, we did not observe viruses pathogenic to humans in the pelagic zone of the lake.

Sanitary-bacteriological monitoring of water quality in Lake Baikal – from single/one-off studies to systematic annual expeditions

“…Sixty-two strains isolated from biofilms and surface water samples were analyzed by modern identification methods (molecular-genetic and mass-spectrometry analyses) (Shtykova et al, 2018a;Shtykova et al, 2020). A total of 18 genera and 21 species of opportunistic bacteria were identified by this In 2021-2023, wastewater samples were taken after the treatment facilities in the Slyudyanka and Severobaikalsk towns, low efficiency of disinfection and inflow of opportunistic and pathogenic bac- teria into Lake Baikal were revealed (Potapov et al, 2023). Seventy bacterial strains isolated from water and 17 strains from wastewater treated at Slyudyanka treatment plant were subjected to antibiotic sensitivity tests, and the results revealed antibiotic resistance to all tested broad-spectrum antibiotics used to treat infectious diseases (penicillins, cephalosporins, carbapenems, macrolides, aminoglycosides, tetracyclines, nitrofurans, etc.…”

“…были взяты пробы сточных вод после прохождения очистных сооружений в гг. Слюдянке и Северобайкальске, установлена низ-кая эффективность обеззараживания и поступление условно-патогенных и патогенных бактерий в Байкал (Potapov et al, 2023). Проведенные исследования чувствительности к антибиотическим веществам у 70 штаммов бактерий, выделенных из воды и у 17 штаммов -из очищенных сточных вод КОС г. Слюдянки, показали антибиотикорезистентность ко всем испытуемым антибиотическим веществам широкого спектра действия, используемых для лечения инфекционных заболеваний (пенициллины, цефалоспорины, карбапенемы, макролиды, аминогликозиды, тетрациклины нитрофураны и др.…”