Weizmannia coagulans strain:MA-13 Genome sequencing and assembly

Background: The transition from a petroleum-based economy towards more sustainable bioprocesses for theproduction of fuels and chemicals (circular economy) is necessary to alleviate the impact of anthropic activities on the global ecosystem. Lignocellulosic biomass-derived sugars are suitable alternative feedstocks that can be fermented or biochemically converted to value-added products. An example is lactic acid, which is an essential chemical for theproduction of polylactic acid, a biodegradable bioplastic. However, lactic acid is still mainly produced by Lactobacillusspecies via fermentation of starch-containing materials, the use of which competes with the supply of food and feed.Results: A thermophilic and cellulolytic lactic acid producer was isolated from bean processing waste and wasidentified as a new strain of Bacillus coagulans, named MA-13. This bacterium fermented lignocellulose-derived sugarsto lactic acid at 55 °C and pH 5.5. Moreover, it was found to be a robust strain able to tolerate high concentrations ofhydrolysate obtained from wheat straw pre-treated by acid-catalysed (pre-)hydrolysis and steam explosion, especiallywhen cultivated in controlled bioreactor conditions. Indeed, unlike what was observed in microscale cultivations(complete growth inhibition at hydrolysate concentrations above 50%), B. coagulans MA-13 was able to grow andferment in 95% hydrolysate-containing bioreactor fermentations. This bacterium was also found to secrete solublethermophilic cellulases, which could be produced at low temperature (37 °C), still retaining an optimal operationalactivity at 50 °C.Conclusions: The above-mentioned features make B. coagulans MA-13 an appealing starting point for future developmentof a consolidated bioprocess for production of lactic acid from lignocellulosic biomass, after further straindevelopment by genetic and evolutionary engineering. Its optimal temperature and pH of growth match with theoperational conditions of fungal enzymes hitherto employed for the depolymerisation of lignocellulosic biomasses tofermentable sugars. Moreover, the robustness of B. coagulans MA-13 is a desirable trait, given the presence of microbialgrowth inhibitors in the pre-treated biomass hydrolysate.