Current status and emerging role of glutathione in food grade lactic acid bacteria

Abstract

Lactic acid bacteria (LAB) have taken centre stage in perspectives of modern fermented food industry and probiotic based therapeutics. These bacteria encounter various stress conditions during industrial processing or in the gastrointestinal environment. Such conditions are overcome by complex molecular assemblies capable of synthesizing and/or metabolizing molecules that play a specific role in stress adaptation. Thiols are important class of molecules which contribute towards stress management in cell. Glutathione, a low molecular weight thiol antioxidant distributed widely in eukaryotes and Gram negative organisms, is present sporadically in Gram positive bacteria. However, new insights on its occurrence and role in the latter group are coming to light. Some LAB and closely related Gram positive organisms are proposed to possess glutathione synthesis and/or utilization machinery. Also, supplementation of glutathione in food grade LAB is gaining attention for its role in stress protection and as a nutrient and sulfur source. Owing to the immense benefits of glutathione, its release by probiotic bacteria could also find important applications in health improvement. This review presents our current understanding about the status of glutathione and its role as an exogenously added molecule in food grade LAB and closely related organisms.

Genomics of Weissella cibaria with an examination of its metabolic traits

“…While some Lactobacillus and Streptococcus strains contain a gene that encodes a bifunctional protein involved in glutathione synthesis (glutathione biosynthesis bifunctional protein, GshAB), with dual activity of the above enzymes, this is not the case here. Thus, glutathione may be imported from the medium, possibly by CydDC, a heterodimeric ABC-type transporter which was shown to be present (Pophaly et al, 2012).…”

Selenite-stress selected mutant strains of probiotic bacteria for Se source production

“…GSH is a low molecular weight thiol antioxidant 54 which has role in the maintenance of intracellular redox homeo-55 stasis to protect the cells against oxidative damage [11]. It is widely 56 distributed in Gram negative organisms, but presents only spo-57 radically in Gram positive bacteria [12]. Most of the biological 58 functions of glutathione are mediated by the conversion of reduced 59 glutathione (GSH) to its oxidized form (GSSG) by glutathione per-60 oxidase and transformation of GSSG back to GSH by glutathione 61 reductase (GR) with simultaneous oxidization of NADPH to NADP + , 62 http://dx.doi.org/10.1016/j.jtemb.2014.11.003 0946-672X/© 2014 Published by Elsevier GmbH.…”

“…Only a few lactic acid bacteria and other Gram positive prokary-302 otes were proven to possess glutathione biosynthetic pathway 303 and most of the lactic acid bacteria were shown to import GSH 304 from their environment [12]. For lactococci, the available data on 305 GSH synthesis were controversy because numerous lactococci were 306 described not to have any capability to perform de novo GSH syn-307 thesis on minimal medium; while, for some of the lactococci, GSH 308 synthesis was proposed when their genomes were annotated and 309 functionally analyzed [12].…”

“…For lactococci, the available data on 305 GSH synthesis were controversy because numerous lactococci were 306 described not to have any capability to perform de novo GSH syn-307 thesis on minimal medium; while, for some of the lactococci, GSH 308 synthesis was proposed when their genomes were annotated and 309 functionally analyzed [12]. A GSH biosynthetic fusion protein is 310 coded in the genome of L. casei (GI:301066250); however, the 311 activity of the gene product has not been demonstrated yet [12]. 312 Moreover, GSH is synthesized by a fusion protein (GshF or GshAB; 313 [22]) in E. faecium when grown in MRS or in other complex media, 314 and this could explain the high GSH content of the parental and 315 mutant E. faecium strains.…”

RNA-Seq reveals transcriptomic interactions of Bacillus subtilis natto and Bifidobacterium animalis subsp. lactis in whole soybean solid-state co-fermentation

“…lactis v9 in the mixed cultures. Glutathione has diverse roles in biological systems, which include antioxidative, immune boosting and cellular detoxifying activities (Pophaly et al, 2012). Enrichment of glutathione could play a vital role in enhancing probiotic effects of the co-fermented product.…”