Abstract

Background and Aim:With respect to the increasing of antibiotic resistance in pathogenic bacteria, identification of new antimicrobial compounds is necessary. Bacterial pigments as bioactive products are one of the agents for identifying new antimicrobial agents. Microorganisms have been considered for the production of new microbial products such as pigments.

Methods: In the present research, a total of 37 pigmented bacterial strains were obtained from soil samples of different regions of Fars province, Iran. These strains contained a wide variety of pigmentation including: red, yellow and green. Strains with different pigmentation were selected for further studies. Pigments were extracted by methanol-water or methanol for secreted and non-secreted pigments, respectively. In order to evaluate the antibacterial activity of pigments, disc diffusion and macrodilution assay were used on MDR Klesiella isolated from clinical samples. Finally, microorganism with anti-bacterial pigment was identified by molecular method. 

Results: Based on the morphology of isolated pigment colonies in different environments and carrying out biochemical tests, the presence of bacteria such as, Pseudomonas aeroginosa, Serratia marcescens, Enterobacter sakazakii, Flavobacter mizutaii, Micrococcus luteus and Staphylococcus aureus were identified. The total frequency of Klebsiella isolates was 8.5%. Of the 17 isolated isolates, 12 isolates were completely resistant to all antibiotics, and six isolates were sensitive to the imipenem antibiotic.

All of Klebsiella isolates were multi drug resistance. A Red pigment from Serratia marcessence was the most potent and showed inhibitory effects on MDR Klebsiella.

Conclusion: Isolated microorganisms from environmental resources contained a very diverse collection of pigments, where different pigment structures with different antimicrobial properties can be searched. The present study indicated that bacterial pigments can be effective against MDR Klebsiella isolates.