Microbial utilization of uncommon C4 dicarboxylate L-tartrate is largely anaerobic, with aerobic L-tartrate utilization known for few bacterial species including Rhodopseudomonas sphaeroides and Pseudomonas putida. Aerobic L-tartrate-utilizing microbes could be industrially relevant owing to the efficient nature of the bioprocess and catalytic versatility of tartrate dehydrogenase (TDH) responsible for aerobic catabolism of L-tartrate. Present work involves isolation and characterization of Bacillus strains capable of aerobic L-tartrate utilization and its correlation with occurrence of TDH activity. Two out of 37 isolates, IC1-G and IC1-Y were identified as Bacillus megaterium spp. showing efficient aerobic growth, utilizing ~3.7 and 2.8 mM L-tartrate respectively at the end of 48 h. Several organic acids possibly including oxalic, succinic and citric acids were secreted as by-products of L-tartrate metabolism. Utilization of L-tartrate directly correlated with induction of TDH activity by ~3.2 and 5.2 folds in IC1-G and IC1-Y respectively, when grown in presence of L-tartrate as compared to when grown on citrate. Overall, this study contributes Bacillus as only the third genus capable of aerobic, TDH mediated L-tartrate utilization. These Bacillus isolates thus offer potential targets to develop an industrially relevant bioprocess and biocatalyst.
L-Tartrate; Bacillus species; Tartrate dehydrogenase.
© The Author(s) 2019. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.