Naslov
Metabolically engineered Lactobacillus gasseri JCM 1131 as a novel producer of optically pure L‑ and D‑lactate

Autori
Žunar, Bojan ; Trontel, Antonija ; Svetec Miklenić, Marina ; Prah, Juliana Lana ; Štafa, Anamarija ; Marđetko, Nenad ; Novak, Mario ; Šantek, Božidar ; Svetec, Ivan Krešimir

Izvornik
World journal of microbiology & biotechnology (0959-3993) 36 (2020), 8; 111, 16

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Bioplastics ; Gene disruption ; Lactate dehydrogenase ; Lactobacillus gasseri ; Optically pure lactate ; Wheat straw hydrolysate

Sažetak
High-quality environmentally-friendly bioplastics can be produced by mixing poly-L- lactate with poly-D-lactate. On an industrial scale, this process simultaneously consumes large amounts of both optically pure lactate stereoisomers. However, because optimal growth conditions of L-lactate producers often differ from those of D-lactate producers, each stereoisomer is produced in a specialised facility, which raises cost and lowers sustainability. To address this challenge, we metabolically engineered Lactobacillus gasseri JCM 1131T, a bioprocess-friendly and genetically malleable strain of homofermenta- tive lactic acid bacterium, to efficiently produce either pure L- or pure D-lactate under the same bioprocess conditions. Transformation of L. gasseri with plasmids carrying additional genes for L- or D-lactate dehydrogenases failed to affect the ratio of produced stereoisomers, but inactivation of the endogenous genes created strains which yielded 0.96 g of either L- or D-lactate per gram of glucose. In this study, the plasmid pHBintE, routinely used for gene disruption in Bacillus megaterium, was used for the first time to inactivate genes in lactobacilli. Strains with inactivated genes for endogenous lactate dehydrogenases efficiently fermented sugars released by enzymatic hydrolysis of alkali pre-treated wheat straw, an abundant lignocellulose- containing raw material, producing 0.37–0.42 g of lactate per gram of solid part of alkali- treated wheat straw. Thus, the constructed strains are primed to serve as producers of both optically pure L-lactate and D-lactate in the next-generation biorefineries.

Izvorni jezik
Engleski

Znanstvena područja
Biotehnologija

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