Batch and repeated batch production of l(+)-lactic acid by Enterococcus faecalis RKY1 using wood hydrolyzate and corn steep liquor

Abstract

Lactic acid production was investigated for batch and repeated batch cultures of Enterococcus faecalis RKY1, using wood hydrolyzate and corn steep liquor. When wood hydrolyzate (equivalent to 50 g l À1 glucose) supplemented with 15-60 g l À1 corn steep liquor was used as a raw material for fermentation, up to 48.6 g l À1 of lactic acid was produced with, volumetric productivities ranging between 0.8 and 1.4 g l À1 h À1 . When a medium containing wood hydrolyzate and 15 g l À1 corn steep liquor was supplemented with 1.5 g l À1 yeast extract, we observed 1.9-fold and 1.6-fold increases in lactic acid productivity and cell growth, respectively. In this case, the nitrogen source cost for producing 1 kg lactic acid can be reduced to 23% of that for fermentation from wood hydrolyzate using 15 g l À1 yeast extract as a single nitrogen source. In addition, lactic acid productivity could be maximized by conducting a cell-recycle repeated batch culture of E. faecalis RKY1. The maximum productivity for this process was determined to be 4.0 g l À1 h À1 .

Lactic Acid Production by Lactobacillus paracasei 168 in Discontinuous Fermentation Using Lucerne Green Juice as Nutrient Substitute

“…In order to produce lactic acid from lucerne green juice (LGJ) in a technical facility, Lactobacillus paracasei 168 was used for developing a suitable fermentation technology. This strain is characterized by a high lactic acid production capacity, a high lactate yield, stability and optical purity of the L-(+)-lactic acid formed [5,12].…”

A novel lactic acid bacterium for the production of high purity l-lactic acid, Lactobacillus paracasei subsp. paracasei CHB2121

“…Although the worldwide production capacity of lactic acid is currently estimated to be 150,000 metric tons annually, this is expected to increase significantly in the near future as a result of rapid expansion in the market for lactic acid derivatives (5). The chemical synthesis of lactic acid from petrochemical resources results in a racemic mixture of DL-lactic acid, which is an amorphous polylactic acid with a relatively low melting point (4,6). On the other hand, the fermentative production of lactic acid produces a high purity L-or Dlactic acid that can be distinguished between by choosing the appropriate microbial strain (1,3).…”

Fermentative production of L(+)‐lactic acid from starch hydrolyzate and corn steep liquor as inexpensive nutrients by batch culture of Enterococcus faecalis RKY1

“…This was improved by supplementation with yeast extract at 1 g L −1 to the fermentation media. 15 This work has demonstrated the ability of E. faecalis RKY1 to produce lactic acid with a low-cost nitrogen source such as CSL in all types of starches, provided that supplementation with a minimal amount of yeast extract is also employed.…”