RelA/(p)ppGpp regulates the glucose-starvation induced stringent response in the zoonostic Streptococcus suis

Growth curves and (p)ppGpp accumulation assays showed that RelA inactivation could influence S. suis growth and led to incapacity of (p)ppGpp synthesis during glucose starvation. To identify the roles of RelA/(p)ppGpp in global gene regulation in S. suis, we compared the transcriptional profiles of SC-19 [a (p)ppGpp+ strain] and ΔrelA [a (p)ppGpp0 strain during glucose starvation] in both glucose-abundant and -deficient CDM in exponential phase by microarray analysis. A less stringent cut-off limit, 2-fold change, was used. qRT-PCR validation displayed the same trends observed in the microarrays relA mutant strain and its parents strain SC-19 were cultured in both glucose-abundant CDM (CDM containing 1% glucose) and glucose-deficient CDM (CDM containing 2% glucose) respectively. The bacteriain in exponential phase were collected for microarray analysis. Three independent experiments were performed.