L-asparaginase (EC 3.5.1.1) hydrolyzes L-asparagine in L-aspartic acid and ammonia. Its efficiency is subject to its kinetics and specificity on the substrate, characteristics that vary from one source to another. Thus, microorganisms from saline environments constitute a phylogenetic and metabolically heterogeneous group for the search of new enzymes. Therefore, the objective of this study was the phenotypic and genotypic characterization of bacteria with L-asparaginase activity isolated from Maras, Pilluana and Chilca salterns. The 24 evaluated bacteria were classified as 38% Gram-negative bacilli and 54% positive; and 8% Gram-positive cocci. The majority grew in 5% salt water, pH 7.0 and 37 °C, all assimilated glucose. Of the 24 bacteria that produced L-asparaginase in solid medium, enzymatic activity was determined in submerged cultures by the Nessler method in 14 of them. The CH11, M62, M64, M68, and P19 strains identified as Bacillus sp., by partial sequencing of the 16S ribosomal gene, presented higher L-asparaginase activity and instability due to the presence of proteases. Saline environments bacteria are potential sources for the prospective production of Lasparaginase to use them as a therapeutic agent and in the food industry.
The aim of this study was to optimize lactic acid production by a native strain (Hui1) of Lactobacillus plantarum isolated from a Peruvian Amazon fruit (Genipa americana) in a medium supplemented with an agroindustrial by-product such as sugar cane molasses. Optimization was performed though one-factor-at-a-time studies followed by the Placket-Burman and central composite designs. The data were analyzed by using the Statistica® 10 software. Several carbon, nitrogen and ion sources were tested, and the optimum concentration of lactic acid achieved was 84.2 g L-1 in a medium containing as follows (in g L-1): meat extract, 18.69; tryptone, 7.88; sugar cane molasses, 140; calcium carbonate, 15; dipotassium phosphate, 1; manganese phosphate, 0.03; sodium acetate, 5, and magnesium sulphate, 0.2. In addition, a high degree of conversion from sugar cane molasses to lactic acid was obtained (Yp/s 0.898 g g-1). These results indicate the potential of Lactobacillus plantarum strain Hui1 to produce lactic acid in a medium supplemented with sugar cane molasses, an underutilized industrial by-product.
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