Carbon substrate utilisation profile of a high concentration effluent degrading microbial consortium

This paper presents the carbon substrate utilisation profile of a group of microorganisms responsible for the biodegradation of a highly concentrated industrial effluent. A 1 litre bioreactor was used to study this consortium's biodegradation potential, with the chemical oxygen demand (COD) of the waste being reduced by 90% from 24000 mg l(-1) within 456 hours. This study also demonstrates that the consortium is capable of degrading organic solvents, such as isopropanol, at concentrations of 260 mg l(-1). The population distribution and biochemical behaviour were also characterised using denaturing gradient gel electrophoresis (DGGE) and Biolog Eco Plates at various stages of bioreactor operation. The DGGE results indicated that the dominant bands of the microbial population profile were stable at various operational stages, and that only a few bands varied with time. Moreover, four Biolog Eco plates were inoculated with samples drawn from the bioreactor at 0, 24, 72 and 120 hours after inoculation. Based on this Biolog Eco Plate profiling, a carbon source utilisation analysis was conducted to group the substrates according to their colour development patterns. Patterns were quantified via measurement of well optical density. Subsequently, cross-correlation statistical techniques were used to establish the existence of recurrent behavioural responses from each carbon source to the various wastewater samples. From the cross correlation, an attempt was made to classify the metabolic potential for future biodegradation processes. Carbohydrates, amino acids and carboxylic acids were the most predominant groups of sole carbon substrates showing similar growth behaviour in the consortium.