Application of FT-IR for characterization of biomass isolated from surface and drinking water with high concentration of natural organic matter

Abstract

Fourier Transform Infrared (FTIR) spectroscopy for identification of bacteria in raw and drinking water samples in which the biomass before the analyses was concentrated from about 0.4 m3 of water with crossflow ultrafiltration (CFUF) method was used. The species of the bacteria were identified based on the analyses of the main biochemical cell components: lipids – 2928 – 2856 cm1; proteins – Amide I and II – 1549 and 1655 cm1; nucleic acids – 1242 cm1, and carbohydrates – 1080 cm1. The applicability of the FTIR methods was tested before and after the enrichment using low nutrient broth (R2A) of CFUF samples. The optimal final concentration for the bacteria identification was found to be in the range from 2×108 and 4×109 cells/ml. Results showed that if water samples after the concentration with CFUF were not enriched on R2A the identification of bacteria was not possible because the peaks (in region 1800 – 716 cm1) from humic substances (HS) overlapped the biochemical cell components peaks. However, after cultivation on R2A for 27 hours selected groups of E. coli, P. fluorescens and B. subtilis in the water samples could be identified applying the Cluster analysis. The study showed that FTIR can be used for the characterization of biomass in oligotrophic water samples after concentration by ultrafiltration, however, prior the analyses enrichment was required. To decrease the time for analyses to less than one day due to enrichment of the samples methods for removing the HS from the concentrated biomass should be developed in the future.