title: Influence of the metabolism pathway on lactic acid production from hemicellulosic trimming vine shoots hydrolyzates using Lactobacillus pentosus.
abstract: Hemicellulosic hydrolyzates from trimming wastes of vine shoots were proposed as a carbon source for lactic acid production by Lactobacillus pentosus CECT-4023T (ATCC-8041). These hydrolyzates are composed mainly of glucose (12.0 g/L), xylose (17.5 g/L) and arabinose (4.3 g/L). Acetic acid, the main subproduct, started to be produced after all of the glucose was completely depleted, showing that the acetic acid coproduction came only from the xylose and arabinose consumption. In the absence of glucose, the L. pentosus pathway shifts from homo to heterofermentative. Thus, L. pentosus can be considered a facultative heterofermentative organism, degrading hexoses (glucose) via the Embden-Meyerhoff-Parnas pathway and pentoses (xylose and arabinose) via the phosphoketolase pathway. Hydrolyzates were vacuum evaporated to increase the initial sugars concentration up to 35.4 g/L of glucose, 52.3 g/L of xylose, and 13.0 g/L of arabinose. Under these conditions the lactic acid concentration reached 46.0 g/L (Q(P) = 0.933 g/L.h, Y(P/S) = 0.78 g/g; Y(P/S) theoretical = 91.7%) and a clear product inhibition was observed. Additional experiments with synthetic sugars, in the absence of inhibitory compounds, indicate that this inhibition must be attributed to the metabolic pathway but not to the inhibitory compounds present in the fermentation broth.
authors.affiliation: Departmento de Ingeniería Química, Universidad de Vigo (Campus Ourense), As Lagoas s/n, 32004 Ourense, Spain.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Bustos
authors.forename: Ana Belén
authors.initials: AB
authors.lastname: Moldes
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Cruz
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Domínguez
mesh_terms: D050260:Carbohydrate Metabolism; D018929:Cell Culture Techniques / Q000379:methods*; D003470:Culture Media / Q000378:metabolism; D006868:Hydrolysis; D007220:Industrial Waste / Q000517:prevention & control; D019344:Lactic Acid / Q000096:biosynthesis*; D007778:Lactobacillus / Q000145:classification / Q000378:metabolism*; D018520:Plant Shoots / Q000737:chemistry*; D011134:Polysaccharides / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D003470:Culture Media; D007220:Industrial Waste; D011134:Polysaccharides; D019344:Lactic Acid; C007916:hemicellulose