Oral administration of Brevibacterium linens from washed cheese increases the proportions of short-chain fatty acid-producing bacteria and lactobacilli in the gut microbiota of mice.

Brevibacterium linens (B. linens) is a dairy microorganism used in the production of washed cheese. However, there has been little research on B. linens, especially regarding its effects in vivo. Herein, we report the morphological characteristics of B. linens, such as its two-phase growth and V- and Y-shaped bodies. We also report that oral administration of B. linens increased the diversity of the gut microbiota and promoted the growth of lactobacilli and short-chain fatty acid-producing bacteria, such as Lachnospiraceae and Muribaculaceae. These findings suggest that the ingestion of B. linens may have beneficial effects in humans and animals.

Construction of Genetically Modified Lactococcus lactis Producing Anti-human-CTLA-4 Single-Chain Fragment Variable.

Lactic acid bacteria are human commensal organisms that have immunomodulatory and metabolism-promoting effects. In addition, due to the increasing demand for biopharmaceuticals, genetically modified lactic acid bacteria (gmLAB) that produce recombinant proteins are expected to be used as microbial therapeutics and next-generation probiotics. In this study, we constructed a gmLAB strain that produces anti-human cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) single-chain fragment variable (CTLA4scFv) for possible use in a cancer treatment strategy using gmLAB. CTLA-4, an immune checkpoint molecule, suppresses the anti-cancer immune response; thus, inhibition of CTLA-4 signaling is important in cancer therapy. In this study, we designed a CTLA4scFv composed of a heavy and light chain of the variable region from anti-human CTLA-4 antibody connected by a flexible peptide linker. CTLA4scFv was expressed using nisin controlled gene expression (NICE) system, a lactococcal inducible gene expression system, and the DNA sequence encoding CTLA4scFv was inserted downstream of the PnisA promoter of the gene expression vector pNZ8148#2. Furthermore, expression of recombinant CTLA4scFv was confirmed by Western blotting, and the immunoreactivity of recombinant CTLA4scFv against human CTLA-4 protein was examined using ELISA. We speculate that gmLAB producing bioactive CTLA4scFv will become an attractive approach for cancer treatment.