Arabinose fermentation by Lactobacillus plantarum in sourdough with added pentosans and alpha-L-arabinofuranosidase: a tool to increase the production of acetic acid

Sixty-five strains of obligately and facultatively heterofermentative sourd ough lactic acid bacteria were screened for their capacity to grow optimall y in the presence of arabinose, ribose and xylose as carbon sources. Lactob acillus alimentarius 15F, Lact. brevis 10A, Lact. fermentum 1F and Lact. pl antarum 20B showed higher growth rate, cell yield, acidification rate and p roduction of acetic acid when some pentoses instead of maltose were added t o the SDB medium. Lactobacillus plantarum 20B used arabinose also in a synt hetic medium where complex growth factors such as yeast extract were omitte d. Other Lact. plantarum strains did not show the same property. Pentosan e xtract was treated with alpha-L-arabinofuranosidase from Aspergillus niger or endo-xylanase from Bacillus subtilis to produce hydrolysates containing mainly arabinose and xylose, respectively. In particular, the hydrolysate c ontaining arabinose substantiated the growth and the production of lactic a cid and, especially, of acetic acid by Lact. plantarum 20B. Sourdough ferme ntation by Lact. plantarum 20B with addition of pentosan extract and alpha- L-arabinofuranosidase increased the acidification rate, titratable acidity and acetic acid content compared with traditional sourdough. A facultativel y heterofermentative strain, Lact. plantarum 20B, also produced a sourdough with an optimal fermentation quotient.