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Among all the pharmaceutical drugs that contaminate the environment, antibiotics occupy an important place due to their high consumption rates in both veterinary and human medicine. The present study examined the ability of Pseudomonas putida to grow on the antibiotic wastewater, currently expanding in Tunisia, containing amoxicillin and cefadroxil. P. putida was very efficient to grow quickly in pharmaceutical wastewater (PW) and in reducing the total dissolved solids to 80.1 %. Cytotoxicity of PW, before and after biodegradation with P. putida mt-2, was evaluated in vitro, using the MTT assay, against four human tumor cell lines such as A549 (lung cell carcinoma), HCT15 (colon cell carcinoma), MCF7 (breast adenocarcinoma), and U373 (glioma cell carcinoma). The PW reduced all human cell lines viability in a dose-dependent manner. This activity was very remarkable against U373 cell line. For this reason, we have tested the genotoxicity of PW using comet assay for quantification of DNA fragmentation. In fact, PW has statistically significant ( p < 0.001) influence on DNA. Indeed, the percentage of genotoxicity was 66.87 and 87.5 %, after 24 and 48 h of treatment, respectively. However, cytotoxicity and genotoxicity decreased strongly when tested the PW obtained after incubation with P. putida mt-2. Our results indicate that P. putida is a promising and improved alternative to treating industrial-scale effluent compared to current chemical treatment procedures used by the industrials. [ABSTRACT FROM AUTHOR]

The endocrine-disrupting chemical bisphenol A (BPA) has attracted much attention because of its estrogenic activity and widespread environmental contamination. In this study, we investigated the BPA biodegradation abilities of various bacterial strains isolated from deserts and arid soils from southern Tunisia. Ten bacterial strains that belong to Pseudomonas putida, Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella sp. and Pantoea sp. showed high BPA removal potential in mineral salt medium (MSM) containing 1 mM BPA. BPA removal rates varied between strains and ranged from 36 to 97%. The strain G320 (P. putida) presented the highest BPA removal rate with 97% within 4 days at 30 °C. The half-life when increasing the BPA concentration to 3 mM was 2 days for strain G320, while total degradation was achieved within 8 days. BPA biodegradation products were identified by GC–MS, and their toxicity was assessed by an algal toxicity test. BPA detoxification was confirmed by evaluating the effect of its biodegradation metabolites on algal growth (dry weight), cells morphology and chlorophylls levels of Tetraselmis sp. strain V2. Results showed the interesting potential of desert soil's bacteria in BPA detoxification as well as the eventual use of the algal specie in toxicity assessment. [ABSTRACT FROM AUTHOR]

Textile industry is considered as one of the important factors of the economic growth in Tunisia. However, this prominent role has certainly some drawbacks mainly represented by the huge amounts of textile wastewaters generated that become a real menace to nature. Many previous studies showed the purifying potential of some activated sludge and bacteria (Pseudomonas putida) to decolourize textile effluents. However, in many cases, decolourization of wastewaters is not necessary associated with detoxification, generating a real risk for the ecosystem in general. We evaluated in this work the induced toxicity of a textile effluent before and after its treatment with activated sludge followed by P. putida, using a battery of biotests. This study proved the detoxifying power of the activated sludge according to most of ecotoxicity tests. The treatment with P. putida did not improve the quality of the effluent; on the contrary, it could increase its toxicity. Daphnia magna and Raphidocelis subcapitata appear to be the most sensitive organisms in assessing eventual toxicity caused by this kind of wastewaters.