Bacteria as bio-indicators of pollution: Application of phospholipid profiling to monitor ecological detriment caused by acid rock drainage
Creators: name: Ben-David, Eric
Publisher: name: figshare
Year: 2021
Subjects: subject: 100204 Environmental Biotechnology Diagnostics (incl. Biosensors)
subject: FOS: Environmental biotechnology
subject: FOS: Environmental biotechnology
subject: 60504 Microbial Ecology
subject: FOS: Biological sciences
subject: FOS: Biological sciences

description: The impact of acid rock drainage (ARD) in stream sediments on microbial communities above and below two abandoned mine sites in South Australia (Brukunga Mine) and in Australia's Northern Territory (Rum Jungle Mine) was quantified by phospholipid profiling (PLFA). This technique has not previously been applied to environmental sites impacted by ARD. The study investigated the relationships between the community structure, biomass and a heavy metal - low pH contamination gradient. The ecosystems studied also suffered from additional environmental insults including sewage and salinity. Physiochemical studies of the water and sediments were conducted in parallel to the PLFA analysis. The PLFA technique was also compared to additional growth and activity methods currently in use such as Biolog™, exoenzyme activities, plate counts and macroinvertebrate counts. Data was accumulated during the period 1998 to 2002. Both univariate and multivariate statistical techniques were applied to the data sets. Redundancy analysis (RDA) was used to identify the environmental parameters with the greatest bearing on the PLFA profiles. Analysis was conducted to compare spatial, seasonal and temporal variations in the PLFA profiles. Multivariate analyses suggested that chemical and biological impacts of ARD downstream Brukunga Mine was limited to 14.5 km in the dry summer period but extended as far as 22 km downstream in other seasons. In contrast ARD impact downstream of the post-rehabilitated Rum Jungle Mine was limited to the first 3 km. The community structure of sediments downstream of both mines was dominated by prokaryotes. Aerobic prokaryotes and heterotrophic eukaryotes composed the largest group, followed by Gram-positive bacteria, with microeukaryotes and SRB present only in minute proportions. Levels of Gram-positive bacteria were consistently suppressed downstream of both mines. Eukaryote levels, particularly fungal markers, were notably elevated just below Brukunga Mine. In contrast, the proportions of eukaryotes were markedly lower downstream Rum Jungle Min. Principal component analysis (PCA) revealed a number of PLFA which were most influential in discriminating between ARD polluted sites and the rest of the sites. These PLFA included the Gram-negative markers: 20Hl2:0, 30Hl2:0, 30Hl4:0; the fungal marker: 18:2w6 and the Acidithiobacillus markers 10mel6:1 and 10mel8:1. The PLFA species 18:2w6, 20Hl2:0, 30Hl2:0 also characterised sites below Rum Jungle Mine. Elevated biomass at heavily ARD impacted sites below both mines was attributed to more favourable conditions for growth of acidophilic microorganisms. The study demonstrated the successful application of PLF A profiling technique to rapidly assess the toxicity of ARD affected waters and sediments and to differentiate this response from the effect of other pollutants, viz increased nutrients and salinity. This technique was sensitive enough to monitor even moderate levels of pollution, such as in Rum Jungle Mine. The technique was particularly useful when the PLFA absolute abundance data were converted to mol% ofthe total fatty acids and analysed by multivariate techniques.