Identification of salt accumulating organisms from winery wastewater
Abstract
n an attempt to find microorganisms that would remove salts from biological winery
wastewater (WWW) treatment plants, 8 halophiles were purchased from culture collections, with a further 40 isolated from WWW plants located in the Barossa Valley and McLaren Vale regions. These organisms were assessed for their ability to accumulate intracellular salt (in particular potassium), remove colour, reduce chemical oxygen demand, change pH and lower the electrical conductivity of a synthetic wastewater.
Summary
- Halophilic synthetic winery wastewater (WWW) was designed to isolate halophiles from WWW. A total of 40 isolates were grown under aerobic and anaerobic conditions.
- These isolates were identified using 16S rRNA gene sequence analysis, and a large phylogenetic diversity was observed
- The ability of these isolates to accumulate intracellular salts (particularly potassium, but also sodium, magnesium and calcium) was determined and some isolates accumulated 5 – 20 times more than others.
- Isolates were also evaluated for their effects on pH and Ec, and reduction in colour and chemical oxygen demand (COD). Generally, isolates did not affect pH or Ec, however there were slight changes in colour (hue) and COD (decrease).
- To eliminate the bias imposed by culture dependant techniques, environmental samples were directly evaluated for intracellular potassium concentration using the fluorescence indicator PBFI with fluorescence activated cell sorting (FACS). Those that gave very strong PBFI signals were separated from the remainder of the population. The DNA was then extracted, the 16S rRNA gene PCR amplified, amplicons separated by insertion into a plasmid and then identified by gene sequencing.
- Five WWW samples were examined by FACS/clone library. Four of the five clone libraries were dominated by a single species, Burkholderia phytofirmans strain PsJN.
This study suggests that halophiles naturally occur in WWWs, with some (Halomonas,Psychrobacter and Arthrobacter sp.) exhibiting the potential to accumulate large concentrations of intracellular potassium.