Lactic acid bacteria isolated from apples are able to catabolise arginine |
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Authors: | María J Savino Leandro A Sánchez Fabiana M Saguir María C Manca de Nadra |
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Institution: | 1.Facultad de Bioquímica, Química y Farmacia,Universidad Nacional de Tucumán,Tucumán,Argentina;2.Planta Piloto de Procesos Industriales (PROIMI),Tucumán,Argentina;3.Centro de Referencia para Lactobacilos (CERELA),Tucumán,Argentina |
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Abstract: | We investigated the potentiality of lactic acid bacteria (LAB) isolated from two apples variety to utilize arginine at different
initial pH values. Apples surface contained average levels of bacteria ranging from log 2.49 ± 0.53 to log 3.73 ± 0.48 cfu/ml
for Red Delicious and Golden Delicious varieties, respectively. Thirty-one strains able to develop in presence of arginine
at low pH were phenotypically and genotipically identified as belonging to Lactobacillus, Pediococcus and Leuconostoc genera. In general, they did not produce ammonia from arginine when cultivated in basal medium with arginine (BMA) at pH
4.5 or 5.2. When this metabolite was quantified only six strains belonging to Leuconostoc dextranicum, Lactobacillus brevis and Lactobacillus plantarum species formed higher ammonia amounts in BMA as compared to control. This was correlated with arginine utilization and it
was more pronounced at pH 4.5 than 5.2. Analysis of citrulline production confirmed the arginine utilization in these bacteria
by the arginine deiminase (ADI) pathway. Maxima citrulline production was observed for Lactobacillus brevis M15 at the two pH values. In this strain ammonia was formed at higher rate than citrulline, which was detected in concentration
lower than 1 mM. Thus, main LAB species found on apple surfaces with abilities to degrade arginine by the ADI pathway under
different conditions were reported here at the first time. The results suggested that the ADI pathway in apples LAB might
not be mainly relevant for their survival in the acid natural environmental, despite leading to the ammonia formation, which
may contribute to the increase in pH, coping the acid stress. |
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