3.1 | Aerobic and anaerobic environment
To evaluate the ability of the bioreactors to maintain aerobic and
anaerobic conditions, two bioreactor modules were inoculated with a
monoculture of the anaerobe Bifidobacterium longum subspeciesinfantis (B. infantis) and operated in the batch culture mode.
This bacterium was able to grow and thrive as indicated by the increase
in the OD600 of the culture after 24 h (Figure 2A).
Analysis of the composition of the culture by qPCR confirmed that the
increase in bacterial density over the 24 h of culture was due to the
growth of B. infantis (Figure 2B). In a separate experiment, a
set of bioreactor modules were inoculated with a mixed bacterial culture
containing different species of bifidobacteria along with other
bacterial species from two of the major phyla (Firmicutes and
Actinobacteria) of the human gut microbiota (Kostic et al., 2013) to
enable us to assess the growth dynamics of bifidobacteria within a mixed
bacterial community. In this experiment, the MRS culture medium (Lee &
Lee, 2008; Süle et al., 2014) was used and the bioreactor modules were
operated in the continuous culture mode. As shown in Figure 2C, the
mixed culture maintained under anaerobic condition showed higher growth
rates compared to that maintained under aerobic condition. Moreover, the
bacterial growth under anaerobic culture condition was attributable to
the growth of Bifidobacterium spp . and Streptococcus
spp. at the expense of the Lactobacillus spp. (Figure 2D). These
results demonstrated the ability of the bioreactor modules to maintain
anaerobic culture conditions and support the growth of anaerobic
bacteria such as bifidobacteria.