Abstract
The aim of the present study was the decolourisation of mixture of two dyes belonging to different groups by two Pseudomonas fluorescens strains (Sz6 and SDz3). Influence of different incubation conditions on decolourisation effectiveness was evaluated. Dyes used in the experiment were diazo Evans blue (EB) and triphenylmethane brilliant green (BG). Another goal of the experiment was the estimation of toxicity of process by-products. Incubation conditions had a significant influence on the rate of decolourisation. The best results were reached in shaken and semistatic samples (exception Evans blue). After 24 h of experiment in semistatic conditions, BG removal reached up to 95.4 %, EB 72.8 % and dyes mixture 88.9 %. After 120 h, all tested dyes were completely removed. In most cases, dyes were removed faster and better by strain Sz6 than SDz3. At the end of the experiment, in majority of the samples, decrease of phyto- and zootoxicity was observed.
Highlights
We focused our attention on the removal efficiency of dyes mixture by two Pseudomonas strains
Brilliant green was better removed than Evans blue (Fig. 1a)
Examined dyes belong to different groups, and different microbial decolourisation mechanism is involved in the process
Summary
Synthetic dyes especially azo and triphenylmethane ones are used in many industrial branches for dyeing of wool, cotton, nylon, leather, paper, cosmetics, pharmaceuticals, food, plastic, petroleum products, etc. (Hamid and Rehman 2009; Koyani et al 2013; Padamavathy et al 2003; Somasiri et al 2006; Swamy and Ramsay 1999; Tony et al 2009; Younes et al 2012). Because of the imperfection of dyeing process, approximately 10– 15 % of the synthetic dyes is released into the industrial waste, causing serious environmental problems worldwide (Hamid and Rehman 2009; Koyani et al 2013; Tony et al 2009; Silveira et al 2009). Synthetic origin of dyes and complex aromatic molecular structure cause that many ofthem are toxic and mutagenic, resistant to biological degradation and may be accumulated in the food chain (Azmi et al 1998; Banat et al 1996; Forgacs et al 2004; Hamid and Rehman 2009; Koyani et al 2013; Pointing and Vrijmoed 2000; Sani and Banerjee 1999). Increasing use of dyes causes an increase of their concentration in the environment and requires the development of new, environmentally and economically
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