Lesser pollution reduction efficiency of strategy could be attributed to the presence of surfactants and preservatives in commercial enzyme samples. Media components present in crude enzymes produced in the lab do not interfere with the catalytic properties of the enzymes and hence do not alter. The use of natural mediators in sequential enzymatic approach resulted in better performance in terms of reduction in pollution load. Therefore, the costs associated with the use of natural mediators can be compensated. The main reason for the reduced acute toxicity observed with the biological processes was the reduced consumption of oxidizing materials during bleaching. However, a variation was observed in the efficiency of the enzymes produced in lab and commercial enzyme Niltubacin HDAC inhibitor systems. This difference in the efficiency could be explained by the presence or absence of chelators and preservatives. Although the sequential application of xylanase and laccase efficiently removes the ligneous material during pretreatment, augmentation of the reaction by mediators caused an increase in the biological load of the effluent generated from these biological processes. Although the mediator was from a natural source, its addition still caused the formation of free radical compounds. Once they formed, they immediately interact with other organic compounds to form highly stable toxicants, which increased the acute toxicity. Because of their natural origin, the concentration of the generated free radical compounds was much less than the intermediates and toxicants generated by the application of synthetic organic mediators. Therefore, application of natural mediator is preferred over synthetic mediator. In addition to being biogeochemically important, scavenging of tropospheric H2 is physiologically unusual; all other characterised hydrogen-oxidising organisms are only capable of recycling the high concentrations of H2 evolved through other biological processes or geothermal activity. The purpose and importance of hydrogen scavenging in the physiology of Actinobacteria nevertheless remains to be understood. It is also to be determined whether this process influences the composition of microorganisms in soil ecosystems. Work in our laboratory has resolved the determinants of hydrogen scavenging. The soil bacterium Mycobacterium smegmatis catalyses atmospheric H2 oxidation using two high-affinity, membrane-associated, oxygen-dependent -hydrogenases. Both of these enzymes are expressed during exponential growth, though their expression and activity is significantly higher during the transition to stationary phase due to carbon-limitation. Despite its low activity, Hyd2 has been shown to be important for the growth of M. smegmatis. Furthermore, orthologs of this enzyme are more widely distributed among sequenced Actinobacteria and are apparently responsible for the tropopheric H2 uptake of streptomycetes and rhodococci. It should also be noted that M. smegmatis also encodes a further hydrogenase, Hyd3; this enzyme is only expressed during oxygenlimitation.