Isolation, Identification and Growth Characteristics of Pseudomonas putida Strain M6 with Malachite Green Decolorization

Abstract:

Six bacterial strains with malachite green decolorization ability were isolated from a sediment of aquaculture pond, and strain M6 was selected by further enrichment culture in nutrition broth with malachite green and decolorization rate comparison. The decolorization rate of strain M6 to malachite green was 97.14% in the conditon of 30°C and 150 r/min, and its morphology was observed by gram stain and electron microscopy, its physiological and biochemical characteristic was studied by ATB bacteria identification instrument for identification of bacteria, and its 16S rDNA sequence was determined following PCR amplification, the sequence was aligned and the phylogenic tree was instructed with those bacterial strains of high identity with strain M6. In addition, its growth characteristics was also studied. The experimental results showed that strain M6 was gram negative and bacilliform with a flagellum at one end. Its size was 0.45 mm ×0.84 mm. Its colony produced on common agar plate appeared as round, light blue, dense, hard to choose; 16S rDNA sequence of strain M6 had high identity of 98%~99% with Pseudomonas sp. located in GenBank and strain M6 had the most close relative relation to Pseudomonas putida OW-16 (Locus number: DQ112328.1). Combined the results of the traditional morphological, physiological, biochemical characteristics and 16S rDNA sequence analysis, strain M6 was identified as Pseudomonas putida (Locus number: EU348741.1). Additionally, its growth curve in the condition of 30°C and 150 r/min was as follows: lag phase was 0~4 h, log phase was 4 h~64 h, stationary phase was 64 h~80 h, decline phase was after 80 h. Its best growth conditions were pH 7 and 30°C,and in the rotational speed of 50 r/min to 250 r/min. Its concentration increased with the increase in rotational speed.