Co-culturing bacteria and microalgae in organic carbon containing medium

Abstract

BackgroundMicroalgae frequently grow in natural environment and long-term laboratory cultures in association with bacteria. Bacteria benefit the oxygen and extracellular substances generated by microalgae, and reimburse microalgae with carbon dioxide, vitamins and so on. Such synergistic relationship has aided in establishing an efficient microalga-bacterium co-culturing mode. Obviously, the mutually beneficial relationship can be strengthened with the increase of the densities of microalgae and bacteria. However, nearly all of the early co-cultures were performed under photoautotrophic conditions, thus both microalgae and bacteria were at relatively low densities. In this study, the feasibility of bacteria-microalgae co-cultured under mixotrophic conditions was studied.ResultsFirstly, bacteria mingled with xenic microalgae were isolated and identified based on their 16S rRNA gene sequence (16S rDNA hereafter). Then, the two most frequently found strains of Muricauda sp. were co-cultured with axenic microalga (Tetraselmis chuii, Cylindrotheca fusiformis and Nannochloropsis gaditana) in extra organic carbon containing medium. At the end of a co-culture period of 33 days, we found that the final cell density of T. chuii and C. fusiformis of various treatments was remarkably higher than that of controls (21.37–31.18 and 65.42–83.47 %, respectively); on the contrary, the growth of N. gaditana was markedly inhibited. During the co-culture of bacteria with C. fusiformis, the cell density of two strains of bacteria firstly decreased, then increased and maintained at a relatively steady level. However, the cell density of bacteria performed a sustaining downward trend when they were co-cultured with T. chuii and N. gaditana.ConclusionsOur findings proved that microalgae-bacteria co-cultures under mixotrophic conditions are quite effective strategy for microalgal cultivation.

A Zeaxanthin-Producing Bacterium Isolated from the Algal Phycosphere Protects Coral Endosymbionts from Environmental Stress

“…Several studies have demonstrated that Muricauda bacteria are intimately associated with microalgae, including Symbiodiniaceae (19,31). However, their functional roles have yet be investigated.…”

Enhanced and Balanced Microalgal Wastewater Treatment (COD, N, and P) by Interval Inoculation of Activated Sludge

“…However, a higher bacteria/algae ratio than optimum caused a lower assimilation of nutrients [18,26]. Bacteria in the activated sludge consume organic compounds and oxygen produced by the microalgae [27]. COD reduction below the effluent standard of sewage was obtained by controlling the proportion between the algae and bacteria.…”

The Volatilomes of Symbiodiniaceae-Associated Bacteria Are Influenced by Chemicals Derived From Their Algal Partner

“…We identified three bacterial operational taxonomic units (OTUs), belonging to the Labrenzia and Marinobacter genera and an unclassified Chromatiaceae, which occurred in all strains of Symbiodiniaceae (Lawson et al, 2018). Members of the Marinobacter and Labrenzia commonly develop associations with microalgae (Han et al, 2016;Sandhya et al, 2017), and Marinobacter species have previously been isolated from other Symbiodiniaceae cultures (Frommlet et al, 2015). Notably, Labrenzia species (which comprised up to 38.4% of the Symbiodiniaceae microbiome; Lawson et al, 2018) can synthesize the DMS precursor, dimethylsulfoniopropionate (DMSP) (Curson et al, 2017), a sulfur compound also abundantly produced by Symbiodiniaceae (Broadbent et al, 2002;Deschaseaux et al, 2014b).…”