L (+)-lactic acid production by pellet-form Rhizopus oryzae NRRL 395on biodiesel crude glycerol

Abstract

BackgroundGiven its availability and low price, glycerol derived from biodiesel industry has become an ideal feedstock for the production of fuels and chemicals. A solution to reduce the negative environmental problems and the cost of biodiesel is to use crude glycerol as carbon source for microbial growth media in order to produce valuable organic chemicals. In the present paper, crude glycerol was used as carbon substrate for production of L (+)-lactic acid using pelletized fungus R. oryzae NRRL 395 on batch fermentation. More, the experiments were conducted on media supplemented with inorganic nutrients and lucerne green juice.ResultsCrude and pure glycerols were first used to produce the highest biomass yield of R. oryzae NRRL 395. An enhanced lactic acid production then followed up using fed-batch fermentation with crude glycerol, inorganic nutrients and lucerne green juice. The optimal crude glycerol concentration for cultivating R. oryzae NRRL 395 was 75 g l-1, which resulted in a fungal biomass yield of 0.72 g g-1 in trial without lucerne green juice addition and 0.83 g g-1 in trial with lucerne green juice. The glycerol consumption rate was 1.04 g l-1 h-1 after 48 h in trial with crude glycerol 75 g l-1 while in trial with crude glycerol 10 g l-1 the lowest rate of 0.12 g l-1 h-1 was registered. The highest L (+)-lactic acid yield (3.72 g g-1) was obtained at the crude glycerol concentration of 75 g l-1 and LGJ 25 g l-1, and the concentration of lactic acid was approximately 48 g l-1.ConclusionsThis work introduced sustainable opportunities for L (+)-lactic acid production via R. oryzae NRRL 395 fermentation on biodiesel crude glycerol media. The results showed good fungal growth on crude glycerol at 75 g l-1 concentration with lucerne green juice supplementation of 25 g l-1. Lucerne green juice provided a good source of nutrients for crude glycerol fermentation, without needs for supplementation with inorganic nutrients. Crude glycerol and lucerne green juice ratio influence the L (+)-lactic acid production, increasing the lactate productivity with the concentration of crude glycerol.

l-Lactic acid production from glycerol coupled with acetic acid metabolism by Enterococcus faecalis without carbon loss

“…Moreover, different compositions of crude glycerol affect several fermentative productions (9). Several papers also reported the conversions of crude glycerol derived from a biodiesel production to lactic acid (13,30). Therefore, the effect of crude glycerol on fermentation by strain QU 11 must be examined, in order to determine its applicability to industrial lactic acid production.…”

Microbial production of lactic acid: the latest development

“…Metabolic engineering of the strain by deleting the alcohol dehydrogenase and malate dehydrogenase genes moved the metabolic flux to LA formation. R. oryzae NRRL 395 produced 140 g/l LA on potato hydrolysate (Liu et al, 2008) and 48 g/l LA from 75 g/l glycerol enriched with 25 g/l Lucerne green juice and inorganic nutrients (Vodnar et al, 2013). However, a drawback of filamentous fungi is their fast growth in media containing nitrogen sources producing predominantly chitin instead of LA.…”

l -Lactate Production from Biodiesel-Derived Crude Glycerol by Metabolically Engineered Enterococcus faecalis: Cytotoxic Evaluation of Biodiesel Waste and Development of a Glycerol-Inducible Gene Expression System

“…Recently, it was reported that metabolically engineered E. coli produced up to 50 g liter Ϫ1 L-lactate from crude glycerol, with a yield of 93% (36), and the Rhizopus oryzae wild-type strain could produce 48 g liter Ϫ1 L-lactate from 75 g liter Ϫ1 crude glycerol in the presence of supplemental nutrients (37). In contrast, E. faecalis ⌬pfl (ldhL1 ϩ ) could convert 300 mM (27 g liter Ϫ1 ) crude glycerol to L-lactate with a yield of Ͼ99%.…”