Resistance of Lactobacillus casei in plastic‐composite‐support biofilm reactors during liquid membrane extraction and optimization of the lactic acid extraction system

Abstract

Lactic acid fermentations were performed with plastic-composite-support (PCS) disks in solvent-saturated media with Lactobacillus casei subsp. rhamnosus (ATCC 11443). The PCS disks contained 50% (w/w) polypropylene, 35% (w/w) ground soybean hulls, 5% (w/w) yeast extract, 5% (w/w) soybean flour, and 5% (w/w) bovine albumin. Bioassays were performed by growing L. casei in solvent-saturated media after soaking the PCS disks. Eighteen different solvent and carrier combinations were evaluated. Overall, L. casei biofilm fermentation demonstrated the same lactic acid production in solvent-saturated medium as suspended cells in medium without solvents (control). To evaluate PCS solvent-detoxifying properties, two bioassays were developed. When solvent-saturated medium in consecutive equal volumes (10 mL then 10 mL) was exposed to PCS, both media demonstrated lactic acid fermentation equal to the control. However, when solvent-saturated medium with two consecutive unequal volumes (10 mL then 90 mL) was exposed to PCS, some degree of toxicity was observed. Furthermore, iso-octane, tributylphosphate (TBP), and Span 80 were optimized for recovery as 91%, 5%, and 4% (v/v), respectively, with a 1:1 ratio of 1.2 M Na(2)CO(3) stripping solution. Also, recovery by emulsion liquid extraction in the hollow-fiber contactor was minimal due to low recovery at pH 5.0 and incompatibility of the solvent and hollow-fiber material. These results suggest that PCS biofilm reactors can benefit lactic acid fermentation by eliminating the toxic effect from solvent leakage into the fermentation medium from liquid-liquid extractive integrated fermentations.

Microbial biofilms: New catalysts for maximizing productivity of long-term biotransformations

“…Biotechnological processes based on biofilms have received much attention over the last years. Biofilm reactors become more and more interesting not only in the bioremediation area (Celmer et al, 2006;Satoh et al, 2004;Zhao et al, 2006) but also in the field of bulk chemical production like lactic acid, butanol or ethanol (Demirci et al, 2003;Qureshi et al, 2004Qureshi et al, , 2005. In this work, the applicability of biofilms for the production of fine chemicals was evaluated.…”

Investigation of a dual‐particle liquid–solid circulating fluidized bed bioreactor for extractive fermentation of lactic acid

“…To overcome the aforementioned issues, efforts have been made to assimilate different techniques with lactic acid production and recovery, such as membrane processes,2–8 solvent extraction,9–14 electrodialysis,15–17 ion exchange, and adsorption 18–21. However, membrane fouling, low selectivity of polymeric solvents in solvent extraction, fouling of electrodialysis membranes, and energy consumption costs are unresolved issues associated with these technologies.…”

Introduction to Biofilm Engineering

“…There have been numerous studies investigating the applications of biofilms in chemical synthesis, such as Caldicellulosiruptor saccharolyticus biofilms for the generation of hydrogen (Groenestijn et al, 2009), Clostridium beijerinckii biofilms for the production of butanol (Lienhardt et al, 2002), Lactobacillus casei biofilms for the production of lactic acid (Demirci et al, 2003) and recombinant E. coli PHL644 biofilms for the biotransformation of haloindole into L-halotryptophan (Tsoligkas, et al, 2011). In addition, the use of electroactive biofilms for microbial electronsynthesis and clean energy generation has attracted considerable attention.…”