Development of Robust Yeast Strains for Lignocellulosic Biorefineries Based on Genome-Wide Studies.

Lignocellulosic biomass has been widely studied as the renewable feedstock for the production of biofuels and biochemicals. Budding yeast Saccharomyces cerevisiae is commonly used as a cell factory for bioconversion of lignocellulosic biomass. However, economic bioproduction using fermentable sugars released from lignocellulosic feedstocks is still challenging. Due to impaired cell viability and fermentation performance by various inhibitors that are present in the cellulosic hydrolysates, robust yeast strains resistant to various stress environments are highly desired. Here, we summarize recent progress on yeast strain development for the production of biofuels and biochemical using lignocellulosic biomass. Genome-wide studies which have contributed to the elucidation of mechanisms of yeast stress tolerance are reviewed. Key gene targets recently identified based on multiomics analysis such as transcriptomic, proteomic, and metabolomics studies are summarized. Physiological genomic studies based on zinc sulfate supplementation are highlighted, and novel zinc-responsive genes involved in yeast stress tolerance are focused. The dependence of host genetic background of yeast stress tolerance and roles of histones and their modifications are emphasized. The development of robust yeast strains based on multiomics analysis benefits economic bioconversion of lignocellulosic biomass.

Effects of oral Lactobacillus plantarum on hepatocyte tight junction structure and function in rats with obstructive jaundice.

Surgery and infection are prominent risk factors for the development of obstructive cholestasis which in turn is associated with failure of the liver barrier. We studied the effects of oral Lactobacillus plantarum (LP) supplementation on endotoxemia, oxidative stress, apoptosis, and tight junctions of hepatocytes in an experimental model of obstructive jaundice. Fifty male Wistar rats were randomly divided into five groups of 10 each: group I, sham-operated; group II, ligation and division of the common bile duct (BDL); group III, BLD followed by oral LP treatment; group IV, BDL followed by internal biliary drainage (IBD); group V, BDL followed by IBD and oral LP treatment. Hepatocyte apoptosis, plasma reduced glutathione (GSH) and oxidized glutathione (GSSG) levels, and portal blood endotoxin levels were measured and changes in tight junction-associated proteins occludin, claudin-1, claudin-4, and ZO-1 were observed. Compared to the sham-operated group I, significant increases in endotoxemia, apoptosis, and GSSG were observed in group II and significant decreases were observed in group V. Tight junctions were destroyed in group II animals but were not in animals treated with oral LP (groups III and V). An increase in occludin, claudin-1, claudin-4, and ZO-1 mRNA and protein levels were detected in livers in LP-treated animals (group V) compared with group II levels. Oral LP treatment of rats with obstructive jaundice assisted in the return of active hepatic barrier function. These results may lead to treatments to prevent the deleterious effects of obstructive jaundice.