Phytoplankton consortia as a blueprint for mutually beneficial eukaryote-bacteria ecosystems: Biocoenosis ofBotryococcusconsortia

Abstract

Bacteria occupy all major ecosystems and maintain an intensive relationship to the eukaryotes, developing together into complex biomes (i.e., phycosphere and rhizosphere). Interactions between eukaryotes and bacteria range from cooperative to competitive, with the associated microorganisms affecting their host’s development, growth, health and disease. Since the advent of non-culture dependent analytical techniques such as metagenome sequencing, consortia have been described but owing to the complex interactions rarely functionally dissected. Multifaceted analysis of the microbial consortium of the ancient phytoplankton Botryococcus as an attractive model food web revealed that its all abundant bacterial members belong to a distinct niche of biotin auxotrophs, essentially depending on the microalga. In addition, hydrocarbonoclastic bacteria without vitamin auxotrophies, which adversely affect the algal cell morphology, appear evidently decimated. Synthetic rearrangement of a minimal community consisting of alga, mutualistic and parasitic bacteria underpins the model of a eukaryote that domesticates its own mutualistic bacterial “zoo” to manipulate and control its surrounding biosphere. This model of domestication of mutualistic bacteria for the defense against destruents by a eukaryotic host could represent ecologically relevant interactions that cross species boundaries. Metabolic and system reconstruction disentangles the relationships and provide a blueprint for the construction of mutually beneficial synthetic ecosystems.

Large-scale screening of natural genetic resource in the hydrocarbon-producing microalga Botrycoccus braunii identified novel fast-growing strains

“…Improvements to cultivation methods such as mixotrophic 48 and attached cultivation 49 , as well as the high-density cultivation 23 , have great potential to increase the biomass and hydrocarbon productivity of B. braunii. Furthermore, biological research is being developed on the genetic transformation 50 , genome sequencing 51 , and bacterial symbionts 52 , 53 of B. braunii . Although many biotechnological and engineering advances have been made in the course of biomass production and biomass processing techniques to yield biofuels from B. braunii , the high production costs are still one of the major issues for the commercialization of algal biofuel production 54 .…”

Light-harvesting by Botryococcus braunii

“…Four chemical races have been described forming different subclades from the species 35 . A range of bacteria naturally co-occurs with Bb in and around its colony with symbiotic and parasitic relations between the alga and the bacteria 36,37 . This aspect makes it difficult and possibly unwanted, to work with axenic strains in the case of symbiotic relations.…”