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Production of Lactic Acid from Carob, Banana and Sugarcane Lignocellulose Biomass
Lignocellulosic biomass from agricultural residues is a promising feedstock for lactic acid (LA) production. The aim of the current study was to investigate the production of LA from different lignocellulosic biomass. The LA production from banana peduncles using strain Bacillus coagulans with yeast extract resulted in 26.6 g LA·L-1, and yield of 0.90 g LA·g-1 sugars. The sugarcane fermentation with yeast extract resulted in 46.5 g LA·L-1, and yield of 0.88 g LA·g-1 sugars. Carob showed that addition of yeast extract resulted in higher productivity of 3.2 g LA·L-1·h-1 compared to without yeast extract where1.95 g LA·L-1·h-1 was obtained. Interestingly, similar LA production was obtained by the end where 54.8 and 51.4 g·L-1 were obtained with and without yeast extract, respectively. A pilot scale of 35 L using carob biomass fermentation without yeast extract resulted in yield of 0.84 g LA·g-1 sugars, and productivity of 2.30 g LA·L-1·h-1 which indicate a very promising process for future industrial production of LA.
Multi-Product Lactic Acid Bacteria Fermentations: A Review
Industrial biotechnology is a continuously expanding field focused on the application of microorganisms to produce chemicals using renewable sources as substrates. Currently, an increasing interest in new versatile processes, able to utilize a variety of substrates to obtain diverse products, can be observed. A robust microbial strain is critical in the creation of such processes. Lactic acid bacteria (LAB) are used to produce a wide variety of chemicals with high commercial interest. Lactic acid (LA) is the most predominant industrial product obtained from LAB fermentations, and its production is forecasted to rise as the result of the increasing demand of polylactic acid. Hence, the creation of new ways to revalorize LA production processes is of high interest and could further enhance its economic value. Therefore, this review explores some co-products of LA fermentations, derived from LAB, with special focus on bacteriocins, lipoteichoic acid, and probiotics. Finally, a multi-product process involving LA and the other compounds of interest is proposed.
L-(+)-Lactic Acid from Reed: Comparing Various Resources for the Nutrient Provision of B. coagulans
Biotechnological production of lactic acid (LA) is based on the so-called first generation feedstocks, meaning sugars derived from food and feed crops such as corn, sugarcane and cassava. The aim of this study was to exploit the potential of a second generation resource: Common reed (Phragmites australis) is a powerfully reproducing sweet grass which grows in wetlands and creates vast monocultural populations. This lignocellulose biomass bears the possibility to be refined to value-added products, without competing with agro industrial land. Besides utilizing reed as a renewable and inexpensive substrate, low-cost nutritional supplementation was analyzed for the fermentation of thermophilic Bacillus coagulans. Various nutritional sources such as baker’s and brewer’s yeast, lucerne green juice and tryptone were investigated for the replacement of yeast extract. The structure of the lignocellulosic material was tackled by chemical treatment (1% NaOH) and enzymatic hydrolysis (Cellic® CTec2). B. coagulans DSM ID 14-300 was employed for the homofermentative conversion of the released hexose and pentose sugars to polymerizable L-(+)-LA of over 99.5% optical purity. The addition of autolyzed baker’s yeast led to the best results of fermentation, enabling an LA titer of 28.3 g L−1 and a yield of 91.6%.