Research Article: Screening, isolation and molecular identification of biodegrading mycobacteria from Iranian ecosystems and analysis of their biodegradation activity

Date Published: September 20, 2017

Publisher: Springer Berlin Heidelberg

Author(s): Davood Azadi, Hasan Shojaei, Sina Mobasherizadeh, Abass Daei Naser.


Anthropogenic origin pollutants including pesticides, heavy metals, pharmaceuticals and industry chemicals impose many risks to human health and environment and bioremediation has been considered the strategy of choice to reduce the risk of hazardous chemicals. In the current study, we
aimed to screen and characterize mycobacteria from the diverse range of Iranian aquatic and terrestrial ecosystems with harsh and unfavorable environmental conditions that can be utilized for biodegradation of target pollutants. Mycobacteria were isolated from a collection of 90 environmental samples and identified to the species level using conventional microbiological and molecular methods including the PCR amplification of hsp65 and sequence analysis of, 16S rRNA genetic markers. The growth rate of the isolates in presence of pollutants, chromatography, Gibbs and turbidometric methods were used to assess their biodegradation activity. A total of 39 mycobacterial isolates (43.3%) were recovered from 90 samples that belonged to 21 various species consisting of M. fortuitum; 6 isolates, M. flavescens and M. paragordonae; 4 isolates each, M. monacense, M. fredriksbergense and M. aurum; 2 isolates each, 7 single isolates of M. conceptionense, M. porcinum, M. simiae, M. celeriflavum, M. novocastrense, M. neoaurum, M. obuense and 12 isolates that belonged to 8 unknown potentially novel mycobacterial species. The isolates were categorized in three groups based on their bioremediation activity, i.e., 5 (12.8%) organisms without biodegradation activity, 20 (51.2%) organisms with previously reported biodegradation activity, and 14 (35.9%) organisms that showed biodegradation activity but not previously reported. Our results showed that the Iranian ecosystems harbor a good reservoir of diverse mycobacterial species with biodegrading potentiality for neutralizing environmental chemical pollutants.

Partial Text

During past decades and with the advances in science and technology various chemicals and synthetic products such as petroleum derivatives like petrochemicals and plastic, insecticides and herbicides, radioactive substances and many other similar materials were increasingly introduced into the environment (Eisenbud and Gesell 1997; El-Shahawi et al. 2010; Petry et al. 1996; Samanta et al. 2002; White et al. 2010). Most of these contaminants are of anthropogenic origin and derived from industrial effluent discharges, point contaminant spills, and diffuse agricultural sources (Ritter et al. 2002; Schwarzenbach et al. 2010). Once in the environment, contaminants can be considered as a source for toxicity and pose adverse effect on the health of living organisms (Mastrangelo et al. 1996; Oliva et al. 2001; Reigart 2009; Thompson et al. 2009). In recent years, numerous chemical and physical methods such as dredging and incineration, evaporation, light oxidation, chemical oxidation, adsorption and leaching of soil particles have been applied to decompose and recycle these materials (Arias-Estévez et al. 2008; Perelo 2010; Schaer et al. 2001). However, these approaches are not cost effective and ecofriendly and may cause further damage to the environment by producing and emitting secondary pollutants and in some other cases dispersing pollutant agents make them much more bioavailable and increases their toxicity risk (Khan et al. 2004; Mulligan et al. 2001; Virkutyte et al. 2002). Finding an ecofriendly and rapid degradation approach for these hazardous materials could make a change in promoting public and environmental health. Bioremediation is one of these methods that has attracted much interest amongst scientists and environmentalists for degradation and neutralization of pollutants. Bioremediation is a process that uses organisms, mostly microorganisms and plants, to degrade, reduce toxicity or detoxify waste products and pollutants (Kumar et al. 2011). Therefore, the most important step in bioremediation process is the isolation and characterization of microorganisms capable of decontamination of a particular or a group of pollutants (Adams et al. 2015).

Since the exploration of oil in 1908, Iran has experienced an economic transition, i.e. transformed from traditional agriculture led to industry led. Development, and industrialization in particular, have made immense positive contributions to health, including greater personal and social wealth, as well as vastly improved health, transportation and communication. Iranian people are living longer and are healthier than they were centuries and even decades ago. However, industrialization has also had adverse health consequences not only for workforces, but for the general population as well. These effects have been caused either directly by exposure to safety hazards and harmful agents, or indirectly through environmental degradation locally and regionally. Iranian people are being exposed to these environmental health hazards through a range of ways that include traditional hazards of industrial contamination of air, water, food and land, as well as new pollution phenomena such as dust and sand storms.




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