Advanced Water Management Centre

Webinar: Aerobic conditions negatively impact purple phototrophic bacteria – Can we still make use of oxygen?

Presented by Dr Tim Huelsen

Anoxygenic purple phototrophic bacteria (PPB) are an emerging biological mediator for resource recovery from various wastewaters, particularly agri-industrial streams. PPB are preeminent photoheterotrophs and can be applied for primary treatment. Under anaerobic, irradiated conditions, PPB simultaneously remove organics, nitrogen and phosphorous and transform these components into protein-rich biomass at yields close to unity. High yields are enabled by phototrophic energy generation via anoxygenic photosynthesis driven by light-harvesting complexes (LHC). These are comprised of bacteriochlorophylls, that absorb infra-red light (>800nm) and a range of carotenoids. The utilisation of IR wavelength is exclusive to PPB and enables selective enrichment and culture dominance in non-sterile environments, such as photobioreactors treating wastewater. However, the light requirements also limit the treatment capacity, particular at night. 

Recently a number of articles claimed that the above can be executed under aerobic conditions. This is in dispute with the literature and also what we observed in the lab. Oxygen has been reported to inhibit the synthesis of the light-harvesting complexes, which inhibits photoheterotrophy. This usually results in a color loss in a matter of hours. While PPB are known to perform aerobic chemoheterotrophic in the dark, it is questionable whether this growth mode still provides a selective advantage. The exploitation of photoheterotrophy during the day and aerobic chemoheterotrophy at night would be extremely interesting. This would result in higher volumetric conversion and removal capacities. Can this be done?

9am - 10am
Friday 1 May
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Event Details
Date & Time: 
Friday, 01 May 2020
9am - 10am
Venue: Zoom Webinar
  • Dr Tim Huelsen

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