Algal growth enhancement by bacteria: Is consumption of photosynthetic oxygen involved?

Abstract

Pseudomonas diminuta and P. vesicularis, two obligate aerobes isolated from laboratory algal cultures, stimulated the growth of the green microalgae Scenedesmus bicellularis and Chlorella sp., without releasing any growth promoting substance. An intimate contact between both microorganisms was necessary for significant algal growth enhancement. The possibility of algal growth stimulation by bacterial attenuation of photosynthetic oxygen tension was indirectly examined by simulating the effect of bacteria through a physical removal of oxygen (air suction). Vacuum‐treated cultures showed an increase in growth rate and photosynthetic activity as compared to the control, a result which cannot be explained by differences in CO2/HCO3− pump activity. In the presence of P. diminuta, the photosynthetic activity of S. bicellularis was more strongly stimulated under a limited concentration of inorganic carbon. It is suggested that, apart from a CO2 supply, aerobic bacteria can promote algal growth by reducing the photosynthetic oxygen tension within the microenvironment of the algal cells, thereby creating more favorable conditions for optimal photosynthetic algal growth.

Bioprospecting of microalgae for integrated biomass production and phytoremediation of unsterilized wastewater and anaerobic digestion centrate

“…The elucidation of these characteristics and the further selection and cultivation of strains with these traits would be highly beneficial for the long-term technology development of algal cultivation in wastewater. Also, several authors have reported on the beneficial effects from microalgae-bacteria (de Bashan et al 2004;Mouget et al 2006;Watanabe et al 2005) and microalgae-fungi (Cheirsilp et al 2011;Shu et al 2013;Watanabe et al 2005) co-cultivation strategies. Such partnerships may have mutualistic or even symbiotic relationships (Watanabe et al 2005) in which the algal Bpartners^generate carbon dioxide and consume oxygen in situ (Adlercreutz et al 1982;Mouget et al 2006), supply essential vitamins (Croft et al 2006;Kazamia et al 2012), increase bioavailability of micronutrients (e.g., iron) (Amin et al 2009), and defend against competitors (Evens et al 2011) to impact overall algal cell development (Matsuo 2005) and metabolic profiles (Paul et al 2012).…”

The effect of the algal microbiome on industrial production of microalgae

“…The main strategy to boost low CO 2 concentrations in algal cultures is to use CO 2 -enriched gases, but additional supply of CO 2 comes with a significant cost (Clarens et al, 2010). Bacterial degradation of organic compounds released by algae contributes an additional source of CO 2 for algal growth, especially during CO 2 -limiting conditions as this CO 2 can be fixed again by algae (Mouget et al, 1995;Subashchandrabose et al, 2011). This is exemplified with the case of a Chlorella sp.…”

Attachment between heterotrophic bacteria and microalgae influences symbiotic microscale interactions

“…The positive 'holobiont' correlations observed in P. tricornutum phycosphere enrichment #2 between algal 13 C incorporation and the 13 C incorporation of their attached bacteria implied that increased algal C fixation resulted in higher quantities of C transferred to their attached bacteria. It is possible that attached bacteria respired the algal C and relieved microscale CO 2 limitation in P. tricornutum (Mouget et al, 1995). This would have had the added effect of removing O 2 from the microenvironment, thus enhancing C fixation efficiency by reducing algal photorespiration (Molina et al, 2001).…”