Lactobacillus, a genus of lactic acid bacteria, plays a crucial function in food production preservation, and probiotics. It is particularly important to develop new Lactobacillus strains with superior performance by gene editing. Currently, the identification of its functional genes and the mining of excellent functional genes mainly rely on the traditional gene homologous recombination technology. CRISPR/Cas9-based genome editing is a rapidly developing technology in recent years. It has been widely applied in mammalian cells, plants, yeast, and other eukaryotes, but less in prokaryotes, especially Lactobacillus. Compared with the traditional strain improvement methods, CRISPR/Cas9-based genome editing can greatly improve the accuracy of Lactobacillus target sites and achieve traceless genome modification. The strains obtained by this technology may even be more efficient than the traditional random mutation methods. This review examines the application and current issues of CRISPR/Cas9-based genome editing in Lactobacillus, as well as the development trend of CRISPR/Cas9-based genome editing in Lactobacillus. In addition, the fundamental mechanisms of CRISPR/Cas9-based genome editing are also presented and summarized.

A microcystin-degrading bacterial strain, Blastomonas fulva T2, was isolated from the culture of a microalgae Microcystis. The strain B. fulva T2 is Gram-stain-negative, non-motile, aerobic, non-spore-forming and phototrophic. The cells of B. fulva T2 are able to grow in ranges of temperature from 15 to 37 °C, with a pH of 6 to 8 and a salinity of 0 to 1% NaCl. Here, we sequenced the complete genome of B. fulva T2, aiming to better understand the evolutionary biology and the function of the genus Blastomonas at the molecular level. The complete genome of B. fulva T2 contained a circular chromosome (3,977,381 bp) with 64.3% GC content and a sizable plasmid (145.829 bp) with 60.7% GC content which comprises about 3.5% of the total genetic content. A total of 3842 coding genes, including 46 tRNAs and 6 rRNAs, were predicted in the genome. The genome contains genes for glycolysis, citric acid cycle, Entner–Doudoroff pathways, photoreaction center and bacteriochlorophylla synthesis. A 7.9 K gene cluster containing mlrA, mlrB, mlrC and mlrD_1,2,3,4 of microcystin-degrading enzymes was identified. Notably, eight different efflux pumps categorized into RND, ABC and MFS types have been identified in the genome of strain T2. Our findings should provide new insights of the alternative reaction pathway as well as the enzymes which mediated the degradation of microcystin by bacteria, as well as the evolution, architectures, chemical mechanisms and physiological roles of the new bacterial multidrug efflux system.