Elucidating the Role and Regulation of a Lactate Permease as Lactate Transporter in Bacillus coagulans DSM1

Abstract

A key feature of Bacillus coagulans is its ability to produce L-lactate via homofermentative metabolism. A putative lactate permease-encoding gene (lutP) and the gene encoding its regulator (lutR) were identified in one operon in B. coagulans strains. LutP orthologs are highly conserved and located adjacent to the gene cluster related to lactate utilization in most lactate-utilizing microorganisms. However, no lactate utilization genes were found adjacent to lutP in all sequenced B. coagulans strains. The stand-alone presence of lutP in L-lactate producers indicates that it may have functions in lactate production. In this study, B. coagulans DSM1 was used as a representative strain, and the critical roles of LutP and its regulation were described. Transport property assays showed that LutP was essential for lactate uptake. Its regulator LutR directly interacted with the lutP-lutR intergenic region, and lutP transcription was activated by L-lactate via regulation by LutR. A biolayer interferometry assay further confirmed that LutR bound to an 11-bp inverted repeat in the intergenic region, and lutP transcription began when the binding of LutR to the lutP upstream sequence was inhibited. We conclusively showed that lutP encodes a functional lactate permease in B. coagulans. IMPORTANCE Lactate-utilizing strains require lactate permease (LutP) to transport lactate into cells. Bacillus coagulans LutP is a previously uncharacterized lactate permease with no lactate utilization genes situated either adjacent to or remotely from it. In this study, an active lactate permease in an L-lactate producer, B. coagulans DSM1, was identified. Lactate supplementation regulated the expression of lactate permease. This study presents physiological evidence of the presence of a lactate transporter in B. coagulans. Our findings indicate a potential target for the engineering of strains in order to improve their fermentation characteristics.

Genomics and cellulolytic, hemicellulolytic, and amylolytic potential of Iocasia fonsfrigidae strain SP3-1 for polysaccharide degradation

“…For example, it is known that operons associated with lactate metabolism are controlled by the GntR family ( Augustiniene & Malys, 2022 ). Specifically, HTH-type transcriptional regulators ( lutR genes) have been shown to regulate genes involved in lactate utilization ( Wang et al., 2019 ). Thus, strain NS-1 T with fewer GntR genes may exhibit reduced efficiency in metabolizing lactate, which SP3-1 readily metabolizes this by-product of glucose utilization.…”

l-Lactic Acid Production via Sustainable Neutralizer-Free Route by Engineering Acid-Tolerant Yeast Pichia kudriavzevii

“…Therefore, ATP will not be sufficient for maintaining cell growth and LA export under anaerobic conditions. 17 It has been demonstrated that LA production does not contribute to the ATP economy of the engineered yeast on oxygen-limited chemostat cultures. 33 Glycolysis is the major pathway for ATP generation in homolactic fermentation (Figure 3a).…”

Revealing the Characteristics of Glucose- and Lactate-Based Chain Elongation for Caproate Production by Caproicibacterium lactatifermentans through Transcriptomic, Bioenergetic, and Regulatory Analyses

“…Different from that, the lldR gene is usually located adjacent to lactate utilization genes ( 22 , 62 , 63 , 66 ), but the lldR gene (GJQ69_00910) in C. lactatifermentans is located downstream of a PTS operon which consists of genes encoding PTS enzyme II (GJQ69_00895, GJQ69_00900) and a phosphoryl carrier protein (HPr, GJQ69_00905) ( Fig. 9A ).…”