Hydroxyapatite (HAp), chemically and compositionally similar to the material presents in bone and has a unique biocompatibility which makes it an attractive material for bone implant. We aimed at studying the physical and chemical properties of HAp synthesized by Serratia sp. The total of 58 strains was isolated from 354 samples obtained from clinical and environmental sources like urine, sputum, soil, water and plant materials. All the isolates were identified as Serratia marcescens by 16S rDNA PCR method and were tested for their phosphatase activity both qualitatively and quantitatively. Distribution of the phosphatase gene (phoA) was analyzed by using specific primers. The organisms which showed the significant level of phosphatase activity (MSS5, 2.42 µmoles min-1µg-1) were used for HAp synthesis using a defined culture medium and the resulting precipitate was sintered and characterized. The presence of apatite in the form of aggregates, rough, granular and dense with regular size was observed under scanning electron microscope and presence of Ca and P in ratio 1:8 was confirmed in EDAX analysis. In XRD, the highest peak (31.92) obtained in the sample showed a similar result when compared to ICSD (No. 026204) standard (31.76) and presence of PO4 and OH group in FTIR confirmed the sintered precipitate as HAp. As a result of the above said analysis, we have proved that the microbial HAp was more similar to that of the HAp which was produced by chemical method. Thus, the microbial HAp could be used as a material in bone implantation.

Keywords: Serratia marcescens, hydroxyapatite, phosphatase, phoA, EDAX.