Growth of Chlamydomonas reinhardtii in acetate-free medium when co-cultured with alginate-encapsulated, acetate-producing strains of Synechococcus sp. PCC 7002

Abstract

BackgroundThe model alga Chlamydomonas reinhardtii requires acetate as a co-substrate for optimal production of lipids, and the addition of acetate to culture media has practical and economic implications for algal biofuel production. Here we demonstrate the growth of C. reinhardtii on acetate provided by mutant strains of the cyanobacterium Synechococcus sp. PCC 7002.ResultsOptimal growth conditions for co-cultivation of C. reinhardtii with wild-type and mutant strains of Synechococcus sp. 7002 were established. In co-culture, acetate produced by a glycogen synthase knockout mutant of Synechococcus sp. PCC 7002 was able to support the growth of a lipid-accumulating mutant strain of C. reinhardtii defective in starch production. Encapsulation of Synechococcus sp. PCC 7002 using an alginate matrix was successfully employed in co-cultures to limit growth and maintain the stability.ConclusionsThe ability of immobilized strains of the cyanobacterium Synechococcus sp. PCC 7002 to produce acetate at a level adequate to support the growth of lipid-accumulating strains of C. reinhartdii offers a potentially practical, photosynthetic alternative to providing exogenous acetate into growth media.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-014-0154-2) contains supplementary material, which is available to authorized users.

Screening of Potential Microalgae Species From Different Natural Environment for Biodiesel Production

“…showed the intense red colour fluorescent which confirms the accumulation of total lipids in microalgae species. In several reports reported the same results by polar lipids (i.e., phospholipids) which are mostly present in membranes, are stained in red whereas neutral lipids (esterified cholesterol and triglycerides) which are present in lipid droplets are stained in yellow [16]. Various factors including algal species and measurement conditions may affect the penetration of Nile red into the cells and binding to lipid bodies causing irreproducible results [17].…”

Biotransformation of 2,4‐dinitrotoluene in a phototrophic co‐culture of engineered Synechococcus elongatus and Pseudomonas putida

“…Previously, we have shown that S. elongatus cells encapsulated within an alginate hydrogel remain metabolically active for months under prolonged nitrogen‐depletion stress (Weiss et al , ). Similarly, immobilization of a variety of cell types in hydrogels has been reported to increase stress tolerance and cell longevity (Bailliez et al , ; Gilleta et al , ; Leino et al , ; Therien et al , ; Ruiz‐Güereca and Sánchez‐Saavedra, ). We therefore examined the viability of alginate‐encapsulated S. elongatus CscB cells and found that they maintained relative Chl( a ) contents at a level similar to that of planktonic cells, even when exposed to 2,4‐DNT concentrations near the solubility limits (250 μM) (Fig.…”

Co-culture for lipid production: Advances and challenges

“…PCC 7002 encapsulated in alginate beads was found to be a potential mechanism for separation and harvesting and later for recycling of Synechococcus sp. cells [61]. Concurrently, encapsulation has been shown to positively modulate the overgrowth of Synechococcus sp and eventually to avoid that a culture took over the co-culture during lipid synthesis.…”

“…The bacteria could inhibit the growth of microalgae by switching their stoichiometry [58,59]. Previous studies have proved that bacteria were able slow algal growth [60,61] and degrade cell wall through cell to cell attachment [62,63]. Thus, many strategies were tested to prevent micro algal cell lysis and many explanations were given to understand this phenomenon.…”

“…Therefore, optimizing co-culture conditions is a prerequisite to weaken the negative competition between the microalgae and bioflocculantproducing bacteria. Therien et al [61] investigated the co-culture of the cyanobacterium, Synechococcus sp. PCC 7002 to produce acetate which is required for lipid production of Chlamydomonas reinhartdii.…”