A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities

Abstract

A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Past studies have evaluated the performance of the reactor for the removal of COD(1) and nitrogen species(2-4) by heterotrophic and chemoautotrophic bacteria, respectively. The HDBR design eliminates the requirement for external flocculation/sedimentation processes while still yielding effluent containing low suspended solids. In this study, the HDBR is applied as a photobioreactor (PBR) in order to characterize the nitrogen removal characteristics of an algae-based photosynthetic microbial community. As previously reported for this HDBR design, a stable biomass zone was established with a clear delineation between the biologically active portion of the reactor and the recycling reactor fluid, which resulted in a low suspended solid effluent. The algal community in the HDBR was observed to remove 18.4% of total nitrogen species in the influent. Varying NH4(+) and NO3(-) concentrations in the feed did not have an effect on NH4(+) removal (n=44, p=0.993 and n=44, p=0.610 respectively) while NH4(+) feed concentration was found to be negatively related with NO3(-) removal (n=44, p=0.000) and NO3(-) feed concentration was found to be positively correlated with NO3(-) removal (n=44, p=0.000). Consistent removal of NH4(+), combined with the accumulation of oxidized nitrogen species at high NH4(+) fluxes indicates the presence of ammonia- and nitrite-oxidizing bacteria within the microbial community.

Emerging investigators series: untangling the microbial ecosystem and kinetics in a nitrogen removing photosynthetic high density bioreactor

“…A synthetic influent, containing no organic carbon, was prepared from mineral salts, as previously described. 57 Influent concentrations of NH 4 + and NO 3 − were varied over several influent conditions resulting in a range of specific loading rates into the reactor.…”

“…A description of the reactor, its operation, sample collection, and the analytical analysis thereof is provided in the ESI; † a comprehensive discussion of the HDBR system and its adaption to a PBR configuration appears in Price et al, 2015. 57 A combination of light (bright field and differential interference contrast (DIC)) and scanning electron microscopy (SEM) were used in an attempt to identify algal species and understand the structure of flocs formed within the HDBR; these methods are described in the ESI. † Incomplete sample pairs (missing influent or effluent samples) were removed from the data set.…”

“…This work describes the kinetic, metabolic, and metagenomic relationships and associations found within a high density bioreactor (HDBR) [54][55][56] which has been adapted to a photobioreactor (PBR) configuration 57 to study the nitrogen removal characteristics. We present and demonstrate the utility found in 3-dimensional (3-D) ) and multiple species and metabolic pathways consume and produce these metabolites.…”

Silk‐based microcarriers: current developments and future perspectives

“…The use of bioreactors, such as stirred tank and rotating chamber reactors, has several advantages. These systems are widely used for microbes [18, 19] and mammalian [20, 21] cells culture under monitored and controlled operational parameters (e.g. pH, temperature, oxygen tension, and nutrient supply) up to an industrial scale [8].…”

Fractional Lotka-Volterra model with time-delay and delayed controller for a bioreactor

“…In addition of its academic and performance predictive importance, mathematical models for bioreactors are required tools for implementing process control strategies demanded in industrial bioprocess. Using these devices, researches have successfully cultivated important kind of cells for the pharmaceutic industry [13], developed complex organ cultures [8,32], designed wastewater treatments [2,29], increased hydrogen production [18], and studied microbial biomass and energy conversion [15], among many other relevant applications.…”