Genes involved in protein metabolism of the probiotic lactic acid bacterium Lactobacillus delbrueckii UFV H2b20

Abstract

A basic requirement for the prediction of the potential use of lactic acid bacteria (LAB) in the dairy industry is the identification of specific genes involved in flavour-forming pathways. The probiotic Lactobacillus delbrueckii UFV H2b20 was submitted to a genetic characterisation and phylogenetic analysis of genes involved in protein catabolism. Eight genes belonging to this system were identified, which possess a closely phylogenetic relationship to NCFM strains representative, as it was demonstrated for oppC and oppBII, encoding oligopeptide transport system components. PepC, PepN, and PepX might be essential for growth of LAB, probiotic or not, since the correspondent genes are always present, including in L. delbrueckii UFV H2b20 genome. For pepX gene, a probable link between carbohydrate catabolism and PepX expression may exists, where it is regulated by PepR1/CcpA-like, a common feature between Lactobacillus strains and also in L. delbrueckii UFV H2b20. The well conserved evolutionary history of the ilvE gene is evidence that the pathways leading to branched-chain amino acid degradation, such as isoleucine and valine, are similar among L. delbrueckii subsp. bulgaricus strains and L. delbrueckii UFV H2b20. Thus, the involvement of succinate in flavour formation can be attributed to IlvE activity. The presence of aminopeptidase G in L. delbrueckii UFV H2b20 genome, which is absent in several strains, might improve the proteolytic activity and effectiveness. The nucleotide sequence encoding PepG revealed that it is a cysteine endopeptidase, belonging to Peptidase C1 superfamily; sequence analysis showed 99% identity with L. delbrueckii subsp. bulgaricus ATCC 11842 pepG, whereas protein sequence analysis revealed 100% similarity with PepG from the same organism. The present study proposes a schematic model to explain how the proteolytic system of the probiotic L. delbrueckii UFV H2b20 works, based on the components identified so far.

Lactobacillus delbrueckii subsp. bulgaricus CRL 454 cleaves allergenic peptides of β-lactoglobulin

“…LAB have an efficient proteolytic system composed of a cell envelope proteinase (which initiates protein degradation), a transport system and several intracellular peptidases. In this respect, certain LAB are able to degrade milk proteins (Do Carmo et al, 2011;Hebert et al, 2008). Moreover, Je ˛drychowski and Wróblewska (2005) have shown that milk fermentation by LAB could reduce 99% of some whey protein allergenicity; however, immunoreactivity of BLG was only slightly reduced.…”

Untargeted metabolic footprinting reveals key differences between fermented brown milk and fermented milk metabolomes

“…The bacteria hydrolyze CN to produce all AA except glutamic acid and cysteine. In particular, L. bulgaricus can produce large amounts of proline, lysine, and valine (Do Carmo et al, 2011). In addition, L. bulgaricus has a complex lactose-degrading enzyme system that can efficiently convert lactose to lactic acid (Burgos-Rubio et al, 2000).…”

Diversity in growth and protein degradation by dairy relevant lactic acid bacteria species in reconstituted whey

“…Several proteolytic enzymes have been identified for Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus ; also, the whole proteolytic system of Lactococcus lactis and several lactobacilli species has been well characterized (Liu et al 2010; Do Carmo et al 2011).…”