An anaerobic, saccharolytic bacterial strain designated GLS2^T was isolated from aggregates of the psychrotolerant archaeon Methanosarcina mazei strain JL01 isolated from arctic permafrost. Bacterial cells were non-motile, spherical, ovoid and annular with diameter 0.2–4 μm. They were chemoorganoheterotrophs using a wide range of mono-, di- and trisaccharides as carbon and energy sources. The novel isolate required yeast extract and vitamins for growth. The bacteria exhibited resistance to a number of β-lactam antibiotics, rifampicin, streptomycin and vancomycin. Optimum growth was observed between 30 and 34 °C, at pH 6.8–7.5 and with 1–2 g NaCl l^− 1. Isolate GLS2^T was a strict anaerobe but it tolerated oxygen exposure. On the basis of 16S rRNA gene sequence similarity, strain GLS2^T was shown to belong to the genus Sphaerochaeta within the family Spirochaetaceae. Its closest relatives were Sphaerochaeta globosa Buddy^T (99.3 % 16S rRNA gene sequence similarity) and Sphaerochaeta pleomorpha Grapes^T (95.4 % similarity). The G+C content of DNA was 47.2 mol%. The level of DNA–DNA hybridization between strains GLS2^T and Buddy^T was 34.7 ± 8.8 %. Major polar lipids were phosphoglycolipids, phospholipids and glycolipids; major fatty acids were C_14 : 0, C_16 : 0, C_16 : 0 3-OH, C_16 : 0 dimethyl acetal (DMA), C_16 : 1n8 and C_16 : 1 DMA; respiratory quinones were not detected. The results of DNA–DNA hybridization, physiological and biochemical tests demonstrated genotypic and phenotypic differentiation of strain GLS2^T from the four species of the genus Sphaerochaeta with validly published names that allowed its separation into a new lineage at the species level. Strain GLS2^T therefore represents a novel species, for which the name Sphaerochaeta associata sp. nov. is proposed, with the type strain GLS2^T ( = DSM 26261^T = VKM B-2742^T).

The possibility of the developing a biochemical oxygen demand (BOD) biosensor based on electroactive biofilms of activated sludge grown on the surface of a graphite-paste electrode modified with carbon nanotubes was studied. A complex of microscopic methods controlled biofilm formation: optical microscopy with phase contrast, scanning electron microscopy, and laser confocal microscopy. The features of charge transfer in the obtained electroactive biofilms were studied using the methods of cyclic voltammetry and electrochemical impedance spectroscopy. The rate constant of the interaction of microorganisms with the extracellular electron carrier (0.79 ± 0.03 dm³(g s)⁻¹) and the heterogeneous rate constant of electron transfer (0.34 ± 0.02 cm s⁻¹) were determined using the cyclic voltammetry method. These results revealed that the modification of the carbon nanotubes’ (CNT) electrode surface makes it possible to create electroactive biofilms. An analysis of the metrological and analytical characteristics of the created biosensors showed that the lower limit of the biosensor based on an electroactive biofilm of activated sludge is 0.41 mgO₂/dm³, which makes it possible to analyze almost any water sample. Analysis of 12 surface water samples showed a high correlation (R² = 0.99) with the results of the standard method for determining biochemical oxygen demand.

Antibiotic-resistant bacteria are recognized as one of the leading causes of death in the world. We proposed and successfully tested peptides with a new mechanism of antimicrobial action “protein silencing” based on directed co-aggregation. The amyloidogenic antimicrobial peptide (AAMP) interacts with the target protein of model or pathogenic bacteria and forms aggregates, thereby knocking out the protein from its working condition. In this review, we consider antimicrobial effects of the designed peptides on two model organisms, E. coli and T. thermophilus, and two pathogenic organisms, P. aeruginosa and S. aureus. We compare the amino acid composition of proteomes and especially S1 ribosomal proteins. Since this protein is inherent only in bacterial cells, it is a good target for studying the process of co-aggregation. This review presents a bioinformatics analysis of these proteins. We sum up all the peptides predicted as amyloidogenic by several programs and synthesized by us. For the four organisms we studied, we show how amyloidogenicity correlates with antibacterial properties. Let us especially dwell on peptides that have demonstrated themselves as AMPs for two pathogenic organisms that cause dangerous hospital infections, and in which the minimal inhibitory concentration (MIC) turned out to be comparable to the MIC of gentamicin sulfate. All this makes our study encouraging for the further development of AAMP. The hybrid peptides may thus provide a starting point for the antibacterial application of amyloidogenic peptides.