Antibacterial effects of bioactive metabolites extracted from Nocardia pseudobrasiliensis

Our study was designed to examine the antimicrobial activity of an Actinobacteria strain previously isolated from soil. In the soil surrounding lemon beebrush (Aloysia citriodora L.), a Nocardia isolate was identified. This strain was evaluated using phenotypic, biochemical, and molecular methods and was distinguished as Nocardia pseudobrasiliensis. The structure of the metabolite was determined using mass spectrometry (MS). The antibacterial activity of this strain was detected during primary screening and was observed to exhibit strong antibacterial effects against important nosocomial infections. These bacterial strains were tested to determine their minimum inhibitory concentration (MIC). The metabolite was first distinguished in N. pseudobrasiliensis. Phylogenetic and biochemical analyses showed that the isolated strain is similar to N. pseudobrasiliensis. The possible molecular structure of the metabolite was distinguished as C18H36O2. Based on these results, the metabolite appears to have strong antimicrobial activity both against Gram-positive and -negative bacteria. Despite the fact that N. pseudobrasiliensis was found in the soil surrounding the lemon beebrush roots, further investigations are necessary in order to determine whether it may be an endophyte or a soil microorganism. In the present study, the C18H36O2 compound in the N. pseudobrasiliensis is reported for the first time.