Response of microbial communities to synthetic winery wastewater in biological sand filters

Abstract

There has been a significant increase in the use of constructed wetlands globally for the bioremediation of wastewater (Welz et al., 2011). In South Africa, the wine industry generates more than one billion litres of wastewater annually and this is disposed of by irrigation (Burton et al., 2007). A more cost effective and simple system need to be employed for the treatment of winery effluent and a possible solution would be the use of biological sand filters (BSFs). The microbial communities present in these BSFs play an important role in the biodegradation of the organic wastewater pollutants. Physicochemical and microbiological studies have been used to determine the performance of BSFs for the remediation of winery effluent since 2009. In this study, changes in the bacterial and fungal communities in different spatial niches was analysed through the use of molecular fingerprinting techniques [terminal restriction fragment length polymorphism (T-RFLP)] of the 16S rRNA gene and fungal ITS gene as a response to the exposure to synthetic winery wastewater and to perform functional studies using q-PCR on selected genes. Changes in the bacterial and fungal community profiles were observed at the different niches after amendment with synthetic winery wastewater. This result was confirmed by performing the phylogenetic analysis on the bacterial population present within the BSF systems. Sand organisms including Clostridium, Sarcina, Streptomyces, Actinobacteria were among the expected species present in the sand samples at the deep inlet of the BSFs. Through the study by Burton et al, (2007), one could hypothesise which organisms mentioned above were able to metabolise the components of the synthetic winery wastewater to secondary metabolites. Amplification of the functional gene through the use of qPCR of catechol 2,3-dioxygenase was successful. Increase in the amount of copy numbers between the samples showed that the increase in expression of the catechol 2,3-dioxygenase meant that there was an increase in the amount of organisms degrading the catehol build-up in the BSF systems.