Analysis of the structural diversity of the microbial community in a paper-mill water system

Abstract

Microbial populations in paper-mill water systems are usually enumerated using microbiological techniques such as plate counts and the most probable number technique. These conventional methods can only quantify a limited percentage of the microbial populations and the microbial numbers are, therefore, generally underestimated. One possible alternative to these methods involves the analysis of signature lipid biomarkers to study the structural diversity of microbial populations. The aim of this study was, therefore, to evaluate the applicability of signature lipid biomarker analysis in a paper-mill water system. Samples from the sessile and planktonic phases were collected over a period of one year at the Sappi Cape Kraft paper-mill. The samples were subjected to analysis of signature lipid biomarkers as well as conventional culturing. Analysis of the phospholipid fatty acids revealed the presence of a large diversity of micro-organisms. The same trends in the number of cultured cells and the counts obtained with signature lipid biomarker analysis were observed, although the numbers obtained with signature lipid biomarker analysis were at least 1 000 times higher. Profiles of signature lipid biomarkers reflected changes in production and water management practices, which could not be detected with culturing techniques. The analysis of signature lipid biomarkers provided more information for the characterisation of microbial communities in paper-mill water systems and has potential for application in other industrial water systems.


WaterSA Vol.28(4) 2002: 407-412