Influence of Nitrogen Sources on D-Lactic Acid Biosynthesis by Sporolactobacillus laevolacticus DSM 442 Strain

Abstract

The purpose of this study was to explore the possibility of replacing an expensive yeast extract contained in the fermentation medium for D-lactic acid (D-LA, R-lactic acid) biosynthesis with an alternative nitrogen source. The screening studies were conducted under stationary conditions and showed that pea seed hydrolysate was the most beneficial substrate in the process of D-LA biosynthesis by the strain Sporolactobacillus laevolacticus DSM 442 among the used inorganic and organic nitrogen sources, waste materials, food and agricultural products. After 96 h, 75.5 g/L D-LA was obtained in batch cultures in a medium containing pea seed hydrolysate, with an average productivity of 0.79 g/L/h, yield of 75.5%, and optical purity of 99.4%. In batch cultures fed once, in a medium with an analogous composition, 122.6 g/L D-LA was obtained after 120 h, and the average yield, productivity and optical purity were 87.6%, 1.021 g/L/h, and 99.6%, respectively. Moreover, the amount of D-LA obtained in the fermentation medium enriched with the above-mentioned cheap agricultural product was similar to the amounts obtained in the medium containing yeast extract in both stationary and bioreactor cultures. Our research shows that hydrolyzed pea seeds, which belong to the legume family, may be a promising nitrogen source for the production of D-LA on an industrial scale.

Association between organic nitrogen substrates and the optical purity of d-lactic acid during the fermentation by Sporolactobacillus terrae SBT-1

“…Nevertheless, most renewable materials cannot be directly utilized for lactic acid fermentation without pretreatment due to insufficient availability of free amino acids and small peptides, which results in a low fermentation performance of lactic acid 24 . As the previous study by Michalczyk et al 25 , who examined various nitrogen sources, including inorganic and organic nitrogen sources, waste materials, food and agricultural products, for d -lactic acid production by S. laevolacticus DSM 442. Their results indicated that yeast extract was still the optimal choice for high levels of d -lactic acid production.…”

“…Their results indicated that yeast extract was still the optimal choice for high levels of d -lactic acid production. In case of using alternative nitrogen source, increasing the nitrogen substrate content was suggested by prior enzymatic hydrolysis for achieving the effectiveness of lactic acid biosynthesis by bacterial strain 25 . Similar to Han et al 6 , various agro-industrial wastes, such as peanut meal, soybean meal, corn steep liquor powder, and ammonium sulfate, were selected to substitute the usage of yeast extract as a sole nitrogen source for lactic acid production.…”

l‐Lactate oxidase‐mediated removal of l‐lactic acid derived from fermentation medium for the production of optically pure D‐lactic acid

“…[18,30,31] Nevertheless, lactic acid production with optical purity above 99% has not been achieved (Table S2, Supporting Information), probably due to the contamination of undesired isomers in CSL. In contrast, several authors successfully produced D-lactic acid with relatively high optical purity (< 99.7%) using other nitrogen sources such as barley extract, [14] pea hydrolysate, [32] cotton seed meal, [33] peanut meal hydrolysate, [34] and whey protein hydrolysate. [35] While lactic acid content in these nitrogen sources was not shown in these reports, they may contain smaller amount of lactic acid compared to CSL.…”