Environmental Risk Assessment and Remediation

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A Study on Mineralisation of Poly cis 1,4 isoprene (NR) and Synthetic Rubber Gloves (SRG) by the bacterial consortium.

Objective: The aim of the study was to isolate bacterial consortium from the effluent contaminated site that is used in the mineralizing both natural rubber and synthetic rubber, to optimise the growth conditions for efficient mineralisation and to biochemically characterise and to use 16s RNA sequencing for identifying the bacterial strains.

Materials and Methods: Natural rubber mineralizing bacterial consortium was isolated from effluent contaminated soil. The mineralisation study was performed for five days at every 24 h interval. Optimization studies were performed with different parameters such as varying concentrations of latex, pH, carbon sources, nitrogen sources, mixed carbon and nitrogen source and different temperature. The bacterial consortium mineralizing nr latex was used to mineralize synthetic rubber gloves (SRG) using the same medium for 40 days at every 5 days interval. Effect of pre-treatment was studied by pre-treating the SRG with acetone and exposing it to sunlight. Mineralisation of the Rubber was confirmed by spectrophotometric and Fourier Transform Infra-Red (FTIR) studies.

Results: Isolated organism was identified as Enterobater cloacae, Microbacterium laevaniformans and Methylobacterium rhodesianum. Maximum mineralisation of (1.66 × 10-4) was shown on the 4th day of incubation. Conformation of NR degradation was done by FTIR analysis that shows the presence of aldehye and ketone produced due to bacterial degradation. The parameters giving optimum results were concentration of latex -1%, pH- 8.5, carbon source- Xylose, nitrogen source- Ammonium Nitrate, temperature- 37°C. Maximum mineralisation of synthetic rubber was shown on the 20th day (1.3 × 10-4). Among the pre-treated and the untreated samples most prominent distortions were visible on the surface of the sunlight sample when visualized under scanning electron microscopy.

Conclusion: From the present investigation, it can be concluded that the isolated bacterial consortium containing the strains Enterobater cloacae, Microbacterium laevaniformans and Methylobacterium rhodesianum were able to mineralize natural rubber as well as synthetic rubber. Which could be applied in the removal of waste rubber products present in the environment.

Author(s): Veenagayathri K*, Ahongsangbam N