Optimisation of a novel rubber degrading strain Brucella sp. BA23

Abstract

In the current study, samples were taken from the sewage treatment plant to isolate rubber-degrading microbial strains. The sludge samples were screened for rubber degradation microbes and later on, each strain was separately characterised for rubber degradation. Initially, strain BA23 showed half the rubber degradation ratio in mineral salt medium. The isolated microbial strains were identified based on 16SrRNA gene sequence analysis, morphological and biochemical characteristics and named Brucella sp. belonging to the genus Bacillus. Later on, the medium conditions for strain BA23 were optimised based on carbon, nitrogen sources, pH, temperature and incubation period. After optimising various environmental and nutritional conditions, the rubber degradation increased twice when inorganic nitrogen sources (aammonium nitrate) used 1 g/L in the medium at pH 7.5. Furthermore, the structural changes that occurred in the rubber polymer associated with the rubber polymer were analysed through Fourier transform infrared spectroscopy (FTIR) and the breakdown of important functional groups such as aldehyde, ketone ester and carboxylic acid was observed. Finally, the gravimetric weight loss of CO₂ during rubber degradation was 42.88 g/L, showing CO₂ evolution greatly when the rubber degradation occurred in the mineral salt medium. It was concluded that strain BA23 has a maximum potential for rubber degradation when it is used for future solid waste management of rubber and its products for a long period in the environment.