Mixed-trophies biofilm cultivation in capillary reactors

Ingeborg Heuschkel,Anna Hoschek,Andreas Schmid,Bruno Bühler,Rohan Karande,Katja Bühler

doi:10.1016/j.mex.2019.07.021

Ingeborg Heuschkel, Anna Hoschek + Show 4 more

Open Access

https://doi.org/10.1016/j.mex.2019.07.021

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Journal: MethodsX	Publication Date: Jan 1, 2019
Citations: 9	License type: cc-by

Affiliation: Helmholtz Centre for Environmental Research

Abstract

The biocatalytic application of photoautotrophic organisms is a promising alternative for the production of biofuels and value-added compounds as they do not rely on carbohydrates as a source of carbon, electrons, and energy. Although the photoautotrophic organisms hold potential for the development of sustainable processes, suitable reactor concepts that allow high cell density (HCD) cultivation of photoautotrophic microorganisms are limited. Such reactors need a high surface to volume ratio to enhance light availability. Furthermore, the accumulation of high oxygen concentrations as a consequence of oxygenic photosynthesis, and its inhibitory effect on cell growth needs to be prevented. Here, we present a method for HCD cultivation of oxygenic phototrophs based on the co-cultivation of different trophies in a biofilm format to avoid high oxygen partial-pressure and attain HCDs of up to 51.8 gBDW L−1 on a lab scale. In this article, we show:•A robust method for mixed trophies biofilm cultivation in capillary reactors•Set-up and operation of a biofilm capillary reactor•A method to quantify oxygen in the continuous biofilm capillary reactor

Highlights

Tubular photobioreactors are applied on a large scale for the production of high-value compounds [3]
Biofilm-based tubular microreactors are mainly restricted due to the fact that: i) not all microorganisms form biofilms in the capillary systems and ii) as a consequence of O2 respiration or O2 evolution, dense cultivation of microbes results in a microenvironment either being O2 limited or O2 overloaded, respectively [7,8]
We developed a method that takes up the concept of microbial mats in a defined and minimized system

Summary

Introduction

(iii) From these pre-cultures main cultures in 20 mL YBG11 medium in 100 mL baffled shake flasks were inoculated to an OD750 of 0.08 and incubated for 3 days under the conditions given in (aii). (iii) For preculture II, 20 mL M9 medium (5 g L-1 citrate, US* trace elements) were inoculated with 200 mL of preculture I and in 100 mL baffled shake flasks and cultivated for 24 h under the same conditions as given in (bii).

Results

Conclusion