Malaysian Applied Biology Journal

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47_05_21

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Malays. Appl. Biol. (2018) 47(5): 173–179

 

LACTIC ACID PRODUCTION FROM DRIED DISTILLER’S

GRAINS WITH SOLUBLES HYDROLYSATE VIA

CO-FERMENTATION OF Lactobacillus pentosus

AND Lactobacillus coryniformis


ZAINI, N.A.M.1,2*, CHARALAMPOPOULOS, D.2 and CHATZIFRAGKOU, A.2


1School of Chemical Sciences and Food Technology, Faculty of Science and Technology,

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

2Department of Food and Nutritional Science, School of Chemistry, Food and Pharmacy,

University of Reading, RG6 6AP Whiteknight, Reading, United Kingdom

*E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it


Accepted 29 October 2018, Published online 30 November 2018


ABSTRACT

Dried Distillers Grains with Soluble (DDGS) is a by-product of bioethanol and distillery industries that is currently marketed as animal feed. DDGS are characterised by high protein and fibre (lignocellulose) content, which shows potential to be utilised as alternative feedstock for microbial fermentations. Lignocellulose hydrolysate is commonly composed of a mixture of hexose and pentose sugars, where the former is always preferable by most of microorganisms but not favourable in economical perspectives. Therefore, the main objective of this study was to optimise the utilisation of DDGS hydrolysate by incorporating pentose-fermenting microorganism together with hexose-fermenting microorganism (Lactobacillus coryniformis) during lactic acid fermentation. Two pentose-fermenting strains, Lactobacillus pentosus and Lactobacillus brevis were analysed for their lactic acid production in MRS broth (to determine the optimal bacterial growth conditions) and DDGS hydrolysate. Result shows that both strains grew well in MRS media, but only L. pentosus can utilise DDGS hydrolysate with 24.9 g/L lactic acid was produced after 18 hr fermentation. In co-fermentation experiment, simultaneous and sequential cultivation technique of L. pentosus with L. coryniformis were tested. Simultaneous co-fermentation of both strains in DDGS hydrolysate exhibited higher lactic acid production with 28.5 g/L lactic acid (18 hr) that corresponded to 83.3% yield. In conclusion, efficient utilisation of both cellulose and hemicellulose components from DDGS hydrolysate employing mixed culture fermentation improved overall lactic acid production.

Key words: DDGS, co-fermentation, lactic acid, L. coryniformis, L. pentosus

 

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