Treatment of saline, acidic, metal-contaminated groundwater from the Western Australian Wheatbelt.

Managing acidic, metal-containing saline ground and drainage waters in the Wheatbelt of Western Australia is an environmental and economic challenge. Sulfate-reducing fluidised bed bioreactors are shown to be technically capable of treating high salt, low pH, metal containing waters from the town of Narembeen in the Wheatbelt so as to reduce acidity and to remove most of the undesirable metal contaminants. The hydraulic residence time (HRT) limit for a stable process with groundwater from the region of Narembeen was >16 hours. The maximal rate of sulfate reduction in the laboratory system treating Narembeen groundwater was similar to rates observed in comparable applications of the process at other sites, ca. 3 g sulfate (L-reactor)(-1) day(-1). Salts that are relatively free of metal contaminants can be produced from water that has been treated by the sulfate-reducing fluidised bed bioreactor. It is unlikely that metal precipitates, captured from Wheatbelt waters by the process, would be of economic value. If sulfate-reducing fluidised bed reactors were considered technologically appropriate at larger scale, the decision to use them would be based on the necessity to take action, the comparative effectiveness of competing technologies, and the relative costs of competing technologies.

The isolation and use of iron-oxidizing, moderately thermophilic acidophiles from the Collie coal mine for the generation of ferric iron leaching solution.

Moderately thermophilic, iron-oxidizing acidophiles were enriched from coal collected from an open-cut mine in Collie, Western Australia. Iron-oxidizers were enriched in fluidized-bed reactors (FBR) at 60 degrees C and 70 degrees C; and iron-oxidation rates were determined. Ferrous iron oxidation by the microbiota in the original coal material was inhibited above 63;C. In addition to four iron-oxidizers, closely related to Sulfobacillus spp that had been earlier isolated from the 60 degrees C FBR, one heterotroph closely related to Alicyclobacillus spp was isolated. The Alicyclobacillus sp. isolated from the Collie coal mine tolerated a lower pH than known Alicyclobacillus spp and therefore may represent a new species. The optimum temperature for growth of the iron-oxidizing strains was approximately 50 degrees C and their maximum temperatures were approximately 60 degrees C. The FBR was adjusted to operate at 50 degrees C and was inoculated with all of the isolated iron-oxidizing strains. At 60 degrees C, an iron-oxidation rate of 0.5 g Fe(2+) l(-1) x h(-1) was obtained. At 50 degrees C, the iron-oxidation rate was only 0.3 g Fe(2+) l(-1) x h(-1). These rates compare favourably with the iron-oxidation rate of Acidianus brierleyi in shake-flasks, but are considerably lower than mesophilic iron-oxidation rates.

Microbial populations associated with treatment of an industrial dye effluent in an anaerobic baffled reactor.

Fluorescent in situ hybridization (FISH) using 16S and 23S rRNA-targeted probes together with construction of an archaeal 16S ribosomal DNA (rDNA) clone library was used to characterize the microbial populations of an anaerobic baffled reactor successfully treating industrial dye waste. Wastewater produced during the manufacture of food dyes containing several different azo and other dye compounds was decolorized and degraded under sulfidogenic and methanogenic conditions. Use of molecular methods to describe microbial populations showed that a diverse group of Bacteria and Archaea was involved in this treatment process. FISH enumeration showed that members of the gamma subclass of the class Proteobacteria and bacteria in the Cytophaga-Flexibacter-Bacteroides phylum, together with sulfate-reducing bacteria, were prominent members of a mixed bacterial population. A combination of FISH probing and analysis of 98 archaeal 16S rDNA clone inserts revealed that together with the bacterial population, a methanogenic population dominated by Methanosaeta species and containing species of Methanobacterium and Methanospirillum and a relatively unstudied methanogen, Methanomethylovorans hollandica, contributed to successful anaerobic treatment of the industrial waste. We suggest that sulfate reducers, or more accurately sulfidogenic bacteria, together with M. hollandica contribute considerably to the treatment process through metabolism of dye-associated sulfonate groups and subsequent conversion of sulfur compounds to carbon dioxide and methane.

PCR detection of Clostridium perfringens producing different toxins in faeces of goats.

A polymerase chain reaction (PCR) was used to identify the genes encoding the major toxins of Clostridium perfringens in faeces of goats. When pure cultures of Cl. perfringens types A, B, C, D and E were used as templates in the PCR, amplicons were observed on the agarose gel as bands at approximately the 247 (alpha primers), 1025 (beta primers), 403 (epsilon primers) and 298 (iota primers) bp level of the DNA marker. When used to identify different types of Cl. perfringens in samples artificially spiked with these micro-organisms, the PCR detected as few as 1-1.5 x 10(2) cfu g-1 of the five types of Cl. perfringens tested. The PCR technique allowed the identification and typing of Cl. perfringens strains in faeces of goats, without recourse to other techniques such as the mouse neutralization test.

Detection by polymerase chain reaction of Clostridium perfringens producing epsilon toxin in faeces and in gastrointestinal contents of goats.

A polymerase chain reaction (PCR) was used to identify the gene-encoding epsilon toxin production in Clostridium perfringens types B and D in faeces and in gastrointestinal contents of goats. The samples were cultured in thioglycollate broth and centrifuged. The upper layer of the pellet was used as a template for PCR, obviating the need for DNA extraction. This technique specifically differentiated Cl. perfringens types B and D from Cl. perfringens types A and C and from Escherichia coli. When used to identify Cl. perfringens type D in samples artificially spiked with the micro-organism, the PCR detected as few as 1.4 x 10(2) cfu g-1 of sample. Gastrointestinal contents and faeces were collected from 20 goats at slaughter and processed by PCR. Several positive results were obtained from the first five goats that were slaughtered and sampled a few days after their arrival at the abattoir, but only a few samples gave positive results during the following weeks, after the goats had been fed a concentrated ration containing monensin. A possible role of this drug in control of enterotoxaemia is suggested.