Date Published: May 24, 2013
Author(s): David Dietz, Wael Sabra, An-Ping Zeng.
In this work a defined co-culture of the lactic acid bacterium Lactobacillus zeae and the propionate producer Veillonella criceti has been studied in continuous stirred tank reactor (CSTR) and in a dialysis membrane reactor. It is the first time that this reactor type is used for a defined co-culture fermentation. This reactor allows high mixing rates and working with high cell densities, making it ideal for co-culture investigations. In CSTR experiments the co-culture showed over a broad concentration range an almost linear correlation in consumption and production rates to the supply with complex nutrients. In CSTR and dialysis cultures a strong growth stimulation of L. zeae by V. criceti was shown. In dialysis cultures very high propionate production rates (0.61 g L-1h-1) with final titers up to 28 g L-1 have been realized. This reactor allows an individual, intracellular investigation of the co-culture partners by omic-technologies to provide a better understanding of microbial communities.
Today most industrial processes are mono-culture processes due to a high degree of control, reproducibility and predictability. But mixed cultures arouse more and more interest. The high potential of mixed culture fermentations for industrial applications has been recently reviewed ( Bader et al. (2010), Sabra et al. (2010)). The authors stress the advantages of mixed cultures beside others in respect of wide substrate and product spectrum. These advantages may be applied e.g. in the fields of food and bioenergy.
In this study a defined co-culture of a lactic acid bacterium, L. zeae, and a propionate producer, V. criceti, has been realized and investigated for the first time in a dialysis chamber reactor.
The authors declare that they have no competing interests.