Use of waste materials for Lactococcus lactis development

Abstract

BACKGROUND: Lactococcus lactis is an interesting microorganism with several industrial applications, particularly in the food industry. As well as being a probiotic species, L. lactis produces several metabolites with interesting properties, such as lactic acid (LA) and biosurfactants. Nevertheless, L. lactis is an especially demanding species since it has strong nutritional requirements, implying the use of complex and expensive culture media. RESULTS: The results showed the potential of L. lactis CECT-4434 as a LA and biosurfactant producer. The economical cost of L. lactis cultures can be reduced by replacing the MRS medium by the use of two waste materials: trimming vine shoots as C source, and 20 g L-1 distilled wine lees (vinasses) as N, P and micronutrient sources. From the hemicellulosic fraction, 14.3 g L-1 LA and 1.7 mg L-1 surfactin equivalent were achieved after 74 h (surface tension reduction of 14.4 mN m-1); meanwhile, a simultaneous saccharification and fermentation process allowed the generation of 10.8 g L-1 LA and 1.5 mg L-1 surfactin equivalent after 72 h, reducing the surface tension by 12.1 units at the end of fermentation. CONCLUSIONS: Trimming vine shoots and vinasses can be used as alternative economical media for LA and cell-bound biosurfactant production. © 2010 Society of Chemical Industry.