Bioprospecting of microorganisms with the potential of exploiting agro-industrial wastes is an active field of biotechnological research. In this study, we aimed to isolate a microorganism adapted to the dairy matrix with specific characteristics to produce lactic acid from dairy industry wastes, such as whey. Whey was collected from the agricultural region of Antioquia, Colombia, and samples were cultured on Man-Rogosa-Sharpe modified medium using lactose as a source of carbon. The most promising strain isolated was characterised, and its adaptation to whey was determined. A gram-positive Lactobacillus was isolated and named as G1. This strain grows in deproteinised whey with low protein requirements, has a homofermentative metabolism and exhibits high tolerance to low pH (≤5.0). The G1 strain is a promising bacterium for use in lactic acid production from whey, which is an underutilised by-product of the dairy industry.
El objetivo de este estudio fue evaluar la actividad antimicrobiana del aceite esencial de Salvia officinalis L. sobre microorganismos transmitidos por alimentos con alto potencial patogénico en humanos. Para determinar su efectividad como alternativa en la conservación de alimentos se comparó con la actividad antimicrobiana de compuestos químicos utilizados ampliamente en la industria de alimentos. El aceite esencial de S. officinalis demostró un amplio espectro de inhibición microbiana sobre microorganismos Gram positivos y Gram negativos. La concentración inhibitoria mínima (CIM) estuvo entre 1 y 4 mg/ml para todas las bacterias evaluadas. Estos resultados muestran que el aceite esencial de S. officinalis puede ser utilizado para mejorar la inocuidad y tiempo de vida útil de productos alimenticios.
The production of lactic acid from agroindustry waste products, such as whey, heavily relies on microorganisms within the genus Lactobacillus. In this work, a genomescale metabolic model was implemented from Vinay-Lara (iLca334_548), improved adding some enzymatic reactions and used to analyse metabolic fl uxes of Lacticaseibacillus paracasei, which is a Lactobacillus strain isolated from whey used in the large-scale production of lactic acid. Overall, the highest rate of lactic acid productivity was 2.9 g l −1 h −1 , which equates to a dilution rate of 0.125 h −1 , when continuous culture conditions were established. Restrictions on lactic acid production caused by exchange reactions, complex culture medium and intracellular metabolite concentrations were considered and included in the model. In total, the iLca334_548 model consisted of 1046 reactions and 959 metabolites, and fl ow balance analysis better predicted lactate fl ux than biomass. The distribution of fl uxes exhibited an increase in lactate formation as biomass decreased. This fi nding is supported by the reactions carried out by glyceraldehyde 3-phosphate dehydrogenase, pyruvate formate lyase and ribose-5-phosphate isomerase, corroborating the modelled phenotype with experimental data. In conclusion, there is potential for the improvement of lactate production in a complex media by amino acid catabolism, especially when lactate is derived from pyruvate.
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