Dynamic membrane-assisted fermentation of food wastes for enhancing lactic acid production

Abstract

A dynamic membrane (DM) module was inserted into a fermentation reactor to separate soluble products from the fermented mixture to increase lactic acid (LA) production from food wastes under acidogenic conditions (uncontrolled pH, pH 4 and 5). With a high total suspended solid content (20-40g/L) in the fermenter, a stable DM could be maintained through regular backwashing. By effectively intercepting suspended solids and lactic acid bacteria (LAB), the fermenter was able to increase microbial activity and largely promote LA yield. Hydrolysis and acidogenesis rates increased with pH, and the highest LA yield (as high as 0.57g/g-TS) was obtained at pH 4. The microbial community analysis showed that the relative abundance of Lactobacillus increased to 96.4% at pH 4, but decreased to 43.3% at pH 5. In addition, the DM could be easily recovered by intercepting larger particles in less than 2h after each cycle of periodic backwashing.

Anaerobic Membrane Bioreactor for Continuous Lactic Acid Fermentation

“…In addition to the operation mode of fermentation, various previous investigations in the literature also used approaches from different aspects to intensify the LA production, reducing its production cost, e.g., utilizing economical feedstock sources [50,51,52], selecting highly-productive strains of microorganisms [53], and optimizing fermentation conditions [31,54]. Moreover, the lactate in the permeate can be treated further by other membrane processes, e.g., bipolar electrodialysis can convert it into LA, while regenerated alkaline can be reused for the neutralization of the fermentation broth [55,56,57].…”

Lactic acid production – producing microorganisms and substrates sources-state of art

“…Food waste contain a high amount of carbohydrate which causing it suitable as a substrate for lactic acid fermentation. Regarding to Table 1, numerous studies stated food waste are suitable for lactic acid production such as kitchen residues/refuse and municipal solid wastes [112], model kitchen refuse medium contain water, vegetables, meat/fish and cereals [113], mixes of cooked rice, vegetables, meat, and bean curd [113,114]; rice, noodles, meat, and vegetables [115,116]; vegetables such as carrot peel, cabbage, and potato peel, fruit such as banana peel, apple peel, and orange peel, baked fish, rice, and used tea leaves [117,118]; rice, noodles, meat and vegetables, and unsold bakery products including cakes, breads and pastries [119]; rice, vegetables, and meat [120]; coffee mucilage [119]; and coffee pulp [121].…”

Integrated Continuous Bioprocess Development for ACE-Inhibitory Peptide Production by Lactobacillus helveticus Strains in Membrane Bioreactor

“…Moreover, it was calculated that 5.3 batch fermentations (whose preparation is time consuming) would be required to obtain the same peptide quantity than the one produced with only one continuous process in MBR. An important lactic acid production was observed during this process; actually, Lactobacillus cultures were generally conducted in MBR to study lactic acid production from various nutrient sources (Choudhury and Swaminathan, 2006;Xu et al, 2006;Probst et al, 2013;Taleghani et al, 2017;Tang et al, 2017). Further optimizations, particularly on the dilution rate applied during the continuous phase, could lead to a further improvement of peptide productivities by this process.…”

“…Indeed, due to membrane retention, bacterial cells and non-hydrolyzed proteins can be concentrated in the bioreactor to undergo an advanced proteolysis during the process. Several studies used Lactobacillus strains in MBR for lactic acid production (Choudhury and Swaminathan, 2006;Xu et al, 2006;Probst et al, 2013;Taleghani et al, 2017;Tang et al, 2017) but to date, no report presented the use of MBR for BAPs production by Lactobacilli.…”