Lactococcus lactis is a microbial species widely used in the dairy industry as a component of starter cultures; it is also employed as a producer of recombinant proteins and biologically active metabolites, as well as in other biotechnological processes. However, genomic editing of these bacteria aimed at conferring them the desired technological properties faces significant challenges due to the lack of convenient tools for rapid and efficient gene knockout and for insertion of large genetic cassettes (several kb long) into the chromosome. Previously, we proposed an adaptation of a system based on a CRISPR-Cas-directed transposon for use in L. lactis. In this work, we improved the previously developed tool by designing a single-plasmid variant instead of the two-plasmid one and by adapting the tetracycline resistance gene as an additional selective marker in L. lactis. The resulting system significantly simplifies and accelerates the delivery of the required genetic material into the chromosome and allows for sequential modification of three different sites using readily available resistance markers (tetracycline, chloramphenicol, and erythromycin resistance genes), which can be later deleted in a single step.
This work presents the first analysis of metagenome-assembled genomes (MAGs) of lake bottom sediments of the Barguzin Depression (Baikal Rift Zone). For soda–saline Lake Gudzhirganskoe, altogether 16 prokaryotic MAGs were distributed across six phyla: Bacillota, Bacteroidota, Deinococcota, Desulfobacterota, Gemmatimonadota, and Pseudomonadota. In soda Lake Nukhe-Nur, 21 prokaryotic MAGs represented six bacterial phyla: Bacteroidota, Bipolaricaulota, Chloroflexota, Deinococcota, Desulfobacterota, and Pseudomonadota, as well as three archaeal phyla: Aenigmatarchaeota, Halobacteriota, and Thermoplasmatota. A significant share of these MAGs (over 76
In silico analysis of the complete genome sequence of potential single-cell protein (SCP) producer, the thermotolerant methanotroph Methylococcus strain COMITA G2, was performed to clarify its taxonomic position and metabolic features. Based on phylogenetic analysis of 16S rRNA gene sequences, the closest taxonomically described phylogenetic relatives of strain COMITA G2 were Methylococcus capsulatus TexasT (98.72
The novel bacterial species Rossellomorea contaminans sp. nov. (strain FM0494T) was isolated as a contaminant from semi-finished catheters. This product originated from a medical supplies production workshop in Guangdong, China. Strain FM0494T consisted of gram-positive, aerobic, and non-motile rods with terminal oval endospores, non-flagellated rods and non-swollen sporangia whose cells formed yellow, raised, opaque and butyrous colonies. Growth was observed at a temperature range of 10–45°C, a pH range of 6.0–8.0, and 0–15
Ferromanganese nodules (FeMnNs), polymetallic ore deposits widespread in the Global Ocean, are important raw materials for metallurgy. Their largest aggregations are associated with deep-water depressions in the Pacific and Indian oceans, where the rate of nodule growth is several mm per 106 years. Contrastingly, FeMnN formation and growth at the sea shelf occurs three orders of magnitude quicker, and the estimated rate for the fastest-growing Baltic Sea nodules is several mm per 100–200 years; they may therefore be considered a renewable ore resource. The biochemogenic concept of nodule formation developed by the world scientific community implies active involvement of marine microorganisms in FeMnN formation via redox transformations of the iron and manganese minerals, which is especially important in the case of fast-growing shallow-water nodules associated with organic-rich benthic ecosystems. Isolation and characterization of the microorganisms involved in the FeMnN ore genesis is a complex task. We present a description of obtaining psychrophilic primary enrichment cultures from the Baltic FeMnN samples which have been developing for several years with oxidized and reduced manganese minerals as electron acceptors and donors, respectively. The work describes phylogenetic profiles, obtained by 16S rRNA gene amplicon sequencing, for the original FeMnNs, their changes during long-term nodule storage, and the profiles of enrichment cultures, in which we revealed taxonomic groups enriched under the conditions selective for manganese minerals transformation. Bioinformatic screening of genomes of these groups representatives for the ability to carry out extracellular electron transfer revealed the key phylotypes which may determine the processes of FeMnNs formation. Our results provide highlights for the isolation and characterization of pure cultures of the microorganisms affecting FeMnN growth. This, in turn, may open the way to directed, controlled synthesis of these ore formations.
