Isolation of Serratia Marcescens from the Soil and In vitro Prodigiosin Production as Source of Antibiotic, Active against Oxacillin-Resistant Staphylococcus aureus

Background: Wide range of microorganisms produced secondary metabolites as microbial activities in extended habitats.

Aims: The aim of this research is the extraction of the red colored pigment, prodigiosin from Serratia marcesens isolated from the soil and evaluate its antibacterial activity against different strains of oxacillin/methicillin-resistant Staphylococcus S. aureus.

Study Design: Two isolates, namely, RMN1 and RMN2, belonging to the Genus, Serratia from two soil samples collected from two strategic locations in University of Abuja, Nigeria were isolated. The isolates were morphologically distinct on the basis of spore colour, aerial and substrate mycelium formation and production of diffusible pigment. Isolates were Gram stained, observed under a microscope and were seen to be Gram negative. Biochemical tests revealed that the two isolates were catalase and citrate positive, and were oxidase negative. One of the two isolates was observed to have significant antibiotic producing potential, and the antibacterial activity of the produced antibiotics (red pigment extracted from cultural supernatants of the isolates grown on Peptone glycerol agar) was assessed using the agar-well diffusion method and streaking agar method.

Results: The results indicated that the pigment extracted in vitro had varying antibacterial activity at different concentrations of 500 mg/ml, 250 mg/ml, 125 mg/ml and 62.5 mg/ml against four strains of the test organism (Staphylococcus aureus) titled S1 to S4, the extracted pigment was more effective at concentration 500 mg/ml against the antibiotic resistant S. aureus with the MIC at 125 mg/ml.

Conclusion: The results indicated that the soil of this region could be a good source of prodigiosin having antibacterial activity and thus enable the use of micro-organisms as biological control agents.