As an important industrial feedstock with various applications, most lactic acid is currently fermented from refined food carbohydrates. To research the feasibility of using non-food feedstock for L-lactic acid production, sweet sorghum bagasse (SSB) as an important lignocellulosic biomass was used by Bacillus coagulans LA1507 in open simultaneous saccharification and fermentation (SSF). In the fed-batch SSF process with a stepwise controlled pH, a cellulase dose of 25 FPU g−1 pretreated SSB and 15 g L−1 corn steep liquor powder (CSLP) were used to produce L-lactic acid from 17.5% (w/v) stover, and B. coagulans LA1507 provided a balanced result which contained a product titer of 111 g L−1, a yield of 0.437 g g−1 crude SSB and an average productivity of 1.59 g L−1 h−1. The process introduces an effective way to produce L-lactic acid from abundant SSB.

In this paper, attempts were made to use defatted rice bran as the only raw material in L-lactic acid fermentation. According to results in shaking flask experiments, the medium with yeast extract, glucose and salts could be completely replaced by defatted rice bran hydrolysates in Lactobacillus rhamnosus cultures. The defatted rice bran medium was then tested in a 5 L fermenter. A productivity of 3.63 g L−1 h−1 in batch fermentation was obtained, which was 1.64 times of that with corn steep powder, and it accounted for 97.06% of that with yeast extract. In the fed-batch fermentation combined with a temperature rise, the concentration, productivity, and yield were 210 g L−1, 2.56 g L−1 h−1, and 93.74% respectively. Furthermore, the work proved the sufficient amount of B vitamins and salts in defatted rice bran hydrolysates, which can introduce an effective way to reduce the raw material cost and be beneficial for L-lactic acid production.

•Organic part in LDHs improves immobilization efficiency and activity of lipase.•Positive charge in LDHs is found to be beneficial to enzyme immobilization.•The immobilized enzyme has a wider pH range and a better thermostability in reaction.In this study, MgAl-LDHs (layered double hydroxides) intercalated with sodium dodecyl sulfate and outside surface modified with (3-aminopropyl)triethoxysilane (KH550) were prepared. The existence of organic part in LDHs improved immobilization efficiency and activity recovery of candida lipolytic lipase loaded. Also the positive charge in framework of LDHs was found to be beneficial to the enzyme immobilization. An immobilization efficiency of 56.4% and an activity recovery over 69.2% of the enzyme were obtained after it was loaded on the intercalated and modified LDHs, and catalytic activity of the immobilization can be kept at least five times. Moreover, the immobilized enzyme was found to have higher temperature resistance, wider pH value and better thermostability in reactive activity.

Dilute glutathione solutions containing NaCl need to be purified and concentrated. Nanofiltration (NF) would be a good solution, provided that it could completely reject glutathione while permeating NaCl entirely. Commercially available NF membranes are incapable of meeting both of these targets. Therefore, in this study, we modified a commercially available NF membrane by the layer-by-layer (LBL) assembly of alternating polyelectrolyte on thin films, to increase both the glutathione rejection and the membrane selectivity for NaCl over glutathione. Poly(styrene sulfonate) (PSS) was selected as the anionic polyelectrolyte, and poly(diallyldimethylammonium chloride) (PDADMAC) was chosen as the cationic polyelectrolyte. The separation performances of the modified membranes were studied with 1 g/L synthetic glutathione solutions containing 2 g/L NaCl at a pressure of 800 kPa. The results demonstrated that the glutathione rejection increased from 74% (unmodified) to 97.27% ([PSS/PDADMAC]10/PSS) and the selectivity for NaCl over glutathione increased from 2.8 (unmodified) to 23 ([PSS/PDADMAC]10/PSS).