Decolourization of azo dye by indigenous bacteria and its impact on seed germination

Textile dyes which are released in environment directly without proper tretament are a potential threat to living organisms. Hence, the present study was designed to isolate azo dye degrading bacteria from a dyes contaminated environment and assessing their ability to degrade reactive dyes into non-toxic product. Three bacteria isolated from textile effluents were identified by 16S rDNA sequencing as Enterobacter sp. S20112. Bacterium MJ20 and Enterobacter aerogenes strain HK20-1. It was found that pH 7.0 and temperature 28°C was suitable for decolourization of Red 3B dye by isolated bacteria. Among these three isolates, Enterobacter sp. decolourized 31.85% and 21.52%, Bacterium MJ20 decolourized 36.58% and 23.72% and Enterobacter aerogenes strain HK 20-1 decolourized 56.58% and 36.58% of 100 ppm and 200 ppm dye respectively. However, the decolourization rate was increased up to 93.44% by yeast extract supplementation. Similarly, the decolourization rate was augmented when Bacterium MJ20 and Enterobacter aerogenes strain HK 20-1 was used together. The effect of dyes from textile industry on seed germination of three leguminous crops pea(Pisum sativum L.), lentil (Lens esculentum L.) and gram (Cicer arietinum L.) were studied. Results revealed that textile dye Red 3B had inhibitory effects on seed germination and seedling growth on test crops. But, deleterious effects of Red 3B dye on seed germination and seedling growth were reduced when dye was used after treatment with isolated bacteria. Thus, these bacterial isolates showed some potentiality to be utilized for the bioremediation of textile effluents into non-toxic form to plants.