Domesticated Cultivation Of Alkali-tolerant And Halophilic Sulphate-reducing Bacteria

The possibility to transform sodium sulphate to sodium carbonate by means ofsulphate-reducing bacteria was previously investigated in this pape in order to cope with theproblems of the chemical productions of soda ash, and to seek the value-added utilizationpathways for Glauber’s salts and/or sodium sulphate, a by-product from industrial processes.First, sludge samples from a local sewage treatment plant were inoculated into enrichmentmedia to obtain bacterial solution. Several strains of sulphate-reducing bacteria were isolatedand purified from the bacterial solution by dilution spread and repeated dish sandwichcultivated methods. Second, the selected strains were inoculated to solid culture media withdifferent NaHCO3content and methanol as carbon source. The highest alkali-tolerant colonywas isolated to be used as a starting strain for alkali-tolerant domestication. During theacclimation, the concentration of NaHCO3was increased stepwise and H2and CO2were usedas energy and carbon sources. A three-neck flask was taken as an incubator whosetemperature was maintained by a water bath and was operated semi-continuously. Theconcentration of sulphate in the media was measured to moniter the growth ofsulphate-reducing bacteria and biological sulphate reduction. The sub-culture was carried outin time intervals of24h or48h according to the sulphate reduction rate. A strain ofsulphate-reducing bacterium grown in media saturated with NaHCO3was obtained afterhalf-a-year cultured, which was gram-positive, straight or curved rod belonged to the genusClostridium based on the16s rRNA analysis. Three different methods of immobilizing SRBwere tested, and calcium-alginate beads, calcium-alginate-xanthan gum beads as well aspolyvinyl alcohol mixed beads were prepared respectively. The mechanical strength ofpolyvinyl alcohol mixed beads was highest.