Algae communication, conspecific and interspecific: the concepts of phycosphere and algal-bacteria consortia in a photobioreactor (PBR)

Abstract

Microalgae in the wild often form consortia with other species promoting their own health and resource foraging opportunities. The recent application of microalgae cultivation and deployment in commercial photobioreactors (PBR) so far has focussed on single species of algae, resulting in multi-species consortia being largely unexplored. Reviewing the current status of PBR ecological habitat, this article argues in favor of further investigation into algal communication with conspecifics and interspecifics, including other strains of microalgae and bacteria. These mutualistic species form the ‘phycosphere’: the microenvironment surrounding microalgal cells, potentiating the production of certain metabolites through biochemical interaction with cohabitating microorganisms. A better understanding of the phycosphere could lead to novel PBR configurations, capable of incorporating algal-microbial consortia, potentially proving more effective than single-species algal systems.

Co-Culturing Microalgae with Roseobacter Clade Bacteria as a Strategy for Vibrionaceae Control in Microalgae-Enriched Artemia

“…However, when co-culturing microalgae with specific bacteria, several aspects shuld be previously considered. Microalgae cells may influence the bacterial population in their microenvironment by the production and excretion of various compounds, which inhibit or promote these bacterial populations [18,[26][27][28]. The two microalgae species used in this study (Phaeodactylum tricornutum and Chlorella minutissima) did not seem to produce any inhibitory compounds for the growth of the bacteria tested (Figure 1).…”

The phycosphere and its role in algal biofuel production

“…The phycosphere is defined as the diffuse region immediately surrounding phytoplankton (single cell or colony) that is nutrient rich and contains numerous signaling molecules (Figure 1). It is an integral part of algae-bacteria interactions and is uncharted territory for engineering applications (Mugnai et al, 2023). It is commonly observed that algal cells secrete organic carbon in various forms into their environment, creating a carbon rich area which attracts heterotrophic bacteria (Seymour et al, 2017).…”

“…It is commonly observed that algal cells secrete organic carbon in various forms into their environment, creating a carbon rich area which attracts heterotrophic bacteria (Seymour et al, 2017). While this relationship benefits the bacteria, it can also benefit the algal cell via a mutualistic relationship (Kazamia et al, 2012;Zhou et al, 2016;Mugnai et al, 2023). Many algae require vitamin B12 to function properly, which is provided by bacteria in the phycosphere (Fuentes et al, 2016;Yao et al, 2019); different bacteria can provide a variety of vitamins including B1 and B7 (Lutzu and Turgut Dunford, 2018;Zhu et al, 2023).…”

“…Bacteria exude compounds that accumulate with increasing cell density, signaling the initiation of lag phase (Miller and Bassler, 2001). Alternatively, bacteria can interrupt or modulate this process in adjacent colonies through quorum quenching (QQ) (Mugnai et al, 2023). The processes involved in QQ vary; bacteria can produce enzymes that degrade QS molecules, or they can produce QS compounds which resemble non-self-bacterium (Rolland et al, 2016).…”