RESUMEN
Lactic acid bacteria can improve their resistance to adverse environments through the formation of biofilm. This study found that adding different buffer salts in culture medium had a great impact on the freeze-drying survival rate of the Lactobacillus plantarum LIP-1, which could be linked to biofilm formation. Transcriptome data showed that potassium ions in buffer salt increased the expression of the luxS gene in the LuxS/autoinducer-2 (AI-2) quorum sensing system and increase synthesis of the quorum sensing signal AI-2. The AI-2 signal molecules up-regulated the cysE gene, which helps to promote biofilm formation. By adding a biofilm inhibitor, d-galactose, and performing a real-time quantitative polymerase chain reaction experiment, we found that d-galactose could down-regulated the luxS and cysE genes, reduced biofilm formation, and decreased the freeze-drying survival rate. The results of this study showed that promoting biofilm formation using appropriate buffer salts may lead to better freeze-drying survival rates.
Asunto(s)
Biopelículas/crecimiento & desarrollo , Medios de Cultivo/química , Liofilización/métodos , Lactobacillus plantarum/efectos de los fármacos , Lactobacillus plantarum/fisiología , Viabilidad Microbiana/efectos de los fármacos , Sales (Química)/farmacología , Proteínas Bacterianas/metabolismo , Biopelículas/efectos de los fármacos , Tampones (Química) , Liasas de Carbono-Azufre/genética , Relación Dosis-Respuesta a Droga , Homoserina/análogos & derivados , Homoserina/metabolismo , Lactobacillus plantarum/citología , Lactobacillus plantarum/metabolismo , Lactonas/metabolismo , Percepción de Quorum/efectos de los fármacos , Tasa de SupervivenciaRESUMEN
Buffer salts are often added to culture medium to promote bacterial growth. However, we found that buffer salts can improve the freeze-drying survival rate. In this experiment, the mechanisms for the effects of different buffer salts on the survival rate of freeze-dried strains were examined. The results showed that buffer salts had important effects on the freeze-drying survival rate of L. plantarum LIP-1 that were related to changes in fatty acid composition. Different buffer salts affected the expression of fatty acid metabolic genes. A new gene cluster that regulates fatty acid metabolism and synthesis was discovered. Potassium ions in buffer salts upregulated the trkA gene and lysR-type transcription factor, and then upregulated the expression of fatty acid synthesis-related acc and fab family genes. These genes help to extend the fatty acid carbon chain and promote the unsaturated fatty acids content, which improves cell membrane fluidity and improves resistance to freeze-drying.
