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In the current era, the alarming rate at which coal is being burned as a fuel is causing concern with regard to the release of sulphur oxides. According to reports, global coal consumption has increased by 0.4% in 2014. While countries like UK, Ukraine etc. have witnessed a decline in coal consumption, some others like India, China, Africa and North America have increased their use of coal to meet the energy requirements of the growing human population. The increasing use of coal has led to extensive investigations for finding an ecofriendly clean coal technology. Dibenzothiophene (DBT) and some of its alkylated derivatives present in the form of organic sulphur in coal have received a great deal of attention in the past few years because of their recalcitrant nature. Considering the economic and environmental prospects, biodesulphurization is being regarded as an effective tool for the degradation of DBT, with concomitant application towards sulphur removal from coal. Owing to the importance of microbial applications towards production of clean coal, the present review discusses some of the recent findings in the area of DBT biodegradation. In addition, current advances in coal biodesulphurization are reviewed, concluding with a consideration of future prospects for the rapidly growing energy sector. [ABSTRACT FROM AUTHOR]

A bacterial strain isolated from a contaminated soil degraded phenol as the sole source of carbon and energy. It was identified as Serratia plymuthica with the help of its biochemical, physiological and morphological characteristics. The bacterium was able to tolerate and degrade phenol up to a concentration of 1050mgl−1. High concentration of phenol in minimal medium had inhibitory effect on bacteria. The bacterium was able to degrade other aromatic compounds like benzoic acid, ortho-, meta-, para-cresol, protocatechuate, catechol and tryptophan. Phenol was degraded through ortho-pathway. Crude cell extract showed presence of ring cleavage enzyme catechol 1,2-dioxygenase. Specific activity of catechol 1,2-dioxygenase was 0.134μmolemin−1 mg−1 protein. Effect of phenol as inhibitory substrate show that higher the concentration of phenol in the medium more is the negative effect on growth of bacteria and subsequent biodegradation. This bacterium grew well in pH range of 5 to 9 and temperature range of 30 to 40°C. Presence of other carbon source like glucose in the phenol minimal medium affects negatively the rate of degradation of phenol but increases the specific growth rate of the bacteria. [Copyright &y& Elsevier]

A native isolate, 9C, identified as Rhodococcus ruber (Genbank Accession number – KY029073) was studied for dibenzothiophene degradation and subsequent bio-desulphurization of three different sulphur bearing materials (NE coal containing organic sulphur; lignite containing pyritic sulphur and a calcined petroleum-coke) of Indian origin. The isolate could degrade 0.25 mM DBT through the 4S pathway within 7 days. Preliminary studies for sulphur removal using the 9C isolate indicated NE coal to be more amenable (29% sulphur removal) followed by Lignite (15.87%) and CPC (14.83%) respectively. Characterization through XRD and FTIR along with the proximate and ultimate analysis of all the samples provided more insights into the changes in calorific values as well as the chemical constitution of the samples following microbial treatment. Owing to the amenability of NE coal, the effect of time, size fraction and pulp density were optimized. The best bio-desulphurization conditions for NE coal indicated 36% total sulphur removal (organic–53%, pyritic–18% and sulphate sulphur–14% respectively). Analytical characterization studies confirmed that the energy value of the NE coal was not affected due to biodesulphurization, rather it contributed towards an increase in gross calorific value from 6698 cal/g to 6812 cal/g following microbial treatment. [ABSTRACT FROM AUTHOR]