Metagenomic analysis of the complex microbial consortium associated with cultures of the oil‐rich alga Botryococcus braunii

Abstract

Microalgae are widely viewed as a promising and sustainable source of renewable chemicals and biofuels. Botryococcus braunii synthesizes and secretes significant amounts of long‐chain (C30‐C40) hydrocarbons that can be subsequently converted into gasoline, diesel, and aviation fuel. B. braunii cultures are not axenic and the effects of co‐cultured microorganisms on B. braunii growth and hydrocarbon yield are important, but sometimes contradictory. To understand the composition of the B. braunii microbial consortium, we used high throughput Illumina sequencing of metagenomic DNA to profile the microbiota within a well established, stable B. braunii culture and characterized the demographic changes in the microcosm following modification to the culture conditions. DNA sequences attributed to B. braunii were present in equal quantities in all treatments, whereas sequences assigned to the associated microbial community were dramatically altered. Bacterial species least affected by treatments, and more robustly associated with the algal cells, included members of Rhizobiales, comprising Bradyrhizobium and Methylobacterium, and representatives of Dyadobacter, Achromobacter and Asticcacaulis. The presence of bacterial species identified by metagenomics was confirmed by additional 16S rDNA analysis of bacterial isolates. Our study demonstrates the advantages of high throughput sequencing and robust metagenomic analyses to define microcosms and further our understanding of microbial ecology.

RETRACTED ARTICLE: Metagenomics for taxonomy profiling: tools and approaches

“…Metagenomic analysis has also been performed on these microorganisms. For instance, Sambles et al [35] used high-throughput Illumina sequencing and 16S rDNA analysis to study the microbial composition of Botryococcus braunii at diverse treatments. The microbial analysis is also crucial in understanding other important components during the bioprocessing of microalgae, such as biofouling of photo-bioreactors [36].…”

The effect of the algal microbiome on industrial production of microalgae

“…For that reason, wastewater treatment with algaebacteria consortia is treated separately in Section 6. The molecular survey of bacterial diversity in three cultures (Nannochloropsis salina from a raceway pond and a closed photobioreactor, respectively, and Botryococcus braunii from laboratory flasks) (Carney et al, 2016;Sambles et al, 2017;Fulbright et al, 2018) and one biofilm sample from an outdoor photobioreactor (mixture of Chlorella vulgaris and Scenedesmus obliquus) (Krohn- Molt et al, 2013) revealed that Deltaproteobacteria and Gammaproteobacteria in raceway pond and Alphaproteobacteria and Bacteroidetes in closed bioreactor were dominant in N. salina, whereas Gammaproteobacteria, Betaproteobacteria and Firmicutes were the most prominent phyla in B. braunii. Alphaproteobacteria, Bacteroidetes, Betaproteobacteria and Gammaproteobacteria made up nearly three-quarters of the biofilm bacterial community.…”

Environmental Factors and Pollution Stresses Select Bacterial Populations in Association With Protists

“…Visible light can act to regulate a sensory module in Caulobacter crescentus in order to increase the biochemical activity and cellular signaling for cell-surface and cell-cell attachment (Purcell et al, 2007). Asticcacaulis was detected in the microbial consortium of the oil-rich green alga Botryococcus braunii (Sambles et al, 2017). In the constant light treatment, continuous uptake of nutrients by the autotrophs, which included those in medium and the Chlorella symbionts inside the P. bursaria, probably lead to nutrient limitation to heterotrophic bacteria in the medium.…”