Nano-sized archaeota, with their small genomes and limited metabolic capabilities, are known to associate with other microbes, thereby compensating for their own auxotrophies. These diminutive and yet ubiquitous organisms thrive in hypersaline habitats that they share with haloarchaea. Here, we reveal the genetic and physiological nature of a nanohaloarchaeon–haloarchaeon association, with both microbes obtained from a solar saltern and reproducibly cultivated together in vitro. The nanohaloarchaeon Candidatus Nanohalobium constans LC1Nh is an aerotolerant, sugar-fermenting anaerobe, lacking key anabolic machinery and respiratory complexes. The nanohaloarchaeon cells are found physically connected to the chitinolytic haloarchaeon Halomicrobium sp. LC1Hm. Our experiments revealed that this haloarchaeon can hydrolyze chitin outside the cell (to produce the monosaccharide N-acetylglucosamine), using this beta-glucan to obtain carbon and energy for growth. However, LC1Hm could not metabolize either glycogen or starch (both alpha-glucans) or other polysaccharides tested. Remarkably, the nanohaloarchaeon’s ability to hydrolyze glycogen and starch to glucose enabled growth of Halomicrobium sp. LC1Hm in the absence of a chitin. These findings indicated that the nanohaloarchaeon–haloarchaeon association is both mutualistic and symbiotic; in this case, each microbe relies on its partner’s ability to degrade different polysaccharides. This suggests, in turn, that other nano-sized archaeota may also be beneficial for their hosts. Given that availability of carbon substrates can vary both spatially and temporarily, the susceptibility of Halomicrobium to colonization by Ca. Nanohalobium can be interpreted as a strategy to maximize the long-term fitness of the host.

Personalized nutrition is of increasing interest to individuals actively monitoring their health. The relations between the duration of diet intervention and the effects on gut microbiota have yet to be elucidated. Here we examined the associations of short-term dietary changes, long-term dietary habits and lifestyle with gut microbiota. Stool samples from 248 citizen-science volunteers were collected before and after a self-reported 2-week personalized diet intervention, then analyzed using 16S rRNA sequencing. Considerable correlations between long-term dietary habits and gut community structure were detected. A higher intake of vegetables and fruits was associated with increased levels of butyrate-producing Clostridiales and higher community richness. A paired comparison of the metagenomes before and after the 2-week intervention showed that even a brief, uncontrolled intervention produced profound changes in community structure: resulting in decreased levels of Bacteroidaceae, Porphyromonadaceae and Rikenellaceae families and decreased alpha-diversity coupled with an increase of Methanobrevibacter, Bifidobacterium, Clostridium and butyrate-producing Lachnospiraceae- as well as the prevalence of a permatype (a bootstrapping-based variation of enterotype) associated with a higher diversity of diet. The response of microbiota to the intervention was dependent on the initial microbiota state. These findings pave the way for the development of an individualized diet.

This paper summarizes information about the division of bacteriocins into classes (Gram-negative bacteria, Gram-positive bacteria, and archaea). Methods for producing bacteriocins have been studied. It is known that bacteriocins, most successfully used today are products of secondary metabolism of lactic acid bacteria. It is established that the main method of bacteriocin research is PCR analysis, which makes it possible to quickly and easily identify the presence of bacteriocin encoding genes. The mechanism of cytotoxic action of bacteriocins has been studied. It is proved that the study of cytotoxic (antitumor) activity in laboratory conditions will lead to the clinical use of bacteriocins for cancer treatment in the near future. It is established that the incorporation of bacteriocins into nanoparticles and targeted delivery to areas of infection may soon become an effective treatment method. The delivery of bacteriocins in a concentrated form, such as encapsulated in nanoparticles, will increase their effectiveness and minimize potential toxic side effects. The analysis of publications on this topic confirmed that diverse research on bacteriocins is relevant.

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Two strains, ‘Pusillimonas nitritireducens’ JR1/69-2-13T and ‘Pusillimonas subterraneus’ JR1/69-3-13T, of aerobic, motile, Gram-negative, non-spore-forming, organotrophic, psychrotolerant bacteria were isolated from a sample of nitrate- and radionuclide-contaminated groundwater in Russia. Here we describe the draft genomes of these strains. The sequenced and annotated genome of the strain JR1/69-2-13T contained 4.3 Mbp with 4108 protein-coding genes. The genome of the strain JR1/69-3-13T contained 4.5 Mbp with 4260 protein-coding genes. Genome analysis of both strains provides an insight into the genomic basis of their resistance to nitrate, heavy metals and metalloids. The draft genome sequences of strains ‘Pusillimonas nitritireducens’ JR1/69-2-13T and ‘Pusillimonas subterraneus’ JR1/69-3-13T are available at DDBJ/EMBL/GenBank under the accession nos. https://www.ncbi.nlm.nih.gov/nuccore/PDNV00000000 and https://www.ncbi.nlm.nih.gov/nuccore/PDNW00000000, respectively.