Selection of Lactobacillus paracasei strains from grated carrots by-products for L-lactic acid production
Abstract
Beside its utilisation as food preservative, lactic acid can also be used to make biopolymers, or to enter in the composition of cleaning products. Nowadays, different ways are explored to optimize its production. The use of vegetable wastes could appear as a profitable option to reduce costs. In this work, 40 different native lactic acid bacteria isolated from fermented carrot pulps were analysed and compared for their ability to produce lactic acid. The selection relied on the use of two model media, the synthetic Man Rogosa and Sharpe (MRS) medium and a sterilized carrot-like medium. This allowed for the isolation of two interesting species: Lactobacillus paracasei and Lactobacillus harbinensis, which produced high concentrations of L-lactic acid in MRS broth. However, the yield obtained with the carrot-like medium was less important and will have to be optimized in the future. L. paracasei proved to be more interesting than L. harbinensis. In particular, the strain A1L was able to metabolize starch. This ability could be a selective advantage in a complex vegetable matrix to overwhelm the other adventitious microorganisms.
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