Biomass and phycocyanin content of heterotrophic Galdieria sulphuraria 074G under maltodextrin and granular starches–feeding conditions

Abstract

A major disadvantage of microalgal cultivation is limited biomass yields due to the autotrophic lifestyle of most microalgal species. Heterotrophic growth on a suitable carbon source and oxygen can overcome such limitations. The red microalga Galdieria sulphuraria strain 074G grows heterotrophically on glucose and a number of other carbon sources while constitutively producing photopigments, including the blue-colored phycocyanin, a natural food colorant. Galdieria sulphuraria strain 074G grew well on maltodextrins as well as on granular starch in combination with the enzyme cocktail Stargen002. The maltodextrin cultures produced 2 mg phycocyanin per gram substrate, being slightly more than on glucose. The phycocyanin extracted from maltodextrin-grown cultures was thermostable up to 55°C. Maltodextrins can be a cheap alternative to glucose syrups for the production of phycocyanin as natural food colorant.

Removal of sugars in wastewater from food production through heterotrophic growth of Galdieria sulphuraria

“…Resulting sugar consumption rates were almost identical. Utilization of hydrolyzed potato starch with G. sulphuraria was also shown recently, where a specific growth rate of 0.82 day −1 was attained [41]. The mentioned growth rates were measured at pH 2 in contrast to this study, where comparable growth rates could be achieved at pH 3 with strain SAG 21.92.…”

Heterotrophic cultivation of Galdieria sulphuraria under non‐sterile conditions in digestate and hydrolyzed straw

“…found for the same strain growth rates of 0.3-0.4 day − 1 in presence of corn and potato starch, respectively (Rahman et al, 2020). In comparison, the doubling time calculated from the growth rates 1.2, 1.0 and 0.9 day − 1 obtained in this study were 18.5 h, 16.6 h and 13.9 h in cyanidium medium, 25 and 50% (v/v) as well as 100% (v/v) digestate, respectively, which lies in the range of doubling times reported earlier (Graziani et al, 2013).…”

Acid Tolerant and Acidophilic Microalgae: An Underexplored World of Biotechnological Opportunities

“…Such enzymes broaden the operational range of bioprocesses. Recently, the presence glucoamylases active at pH 2-2.5 and 80°C have been demonstrated in G. sulphuraria (Rahman et al, 2020). In the whole genome analysis of G. sulphuraria, a range of genes with high similarity with other extremozymes have been identified (Shrestha and Weber, 2007), which gives an indication that extremophilic microalgae can be used as a source extremozymes.…”

“…During the last two decades, increasing attention has been paid toward acidophilic and acid tolerant microalgae and their possible biotechnological applications such as the production of acid stable pigments (Rahman et al, 2017;Ferraro et al, 2020a), rare earth metal biorecovery (Minoda et al, 2015), extremozymes (Rahman et al, 2020) and extremolytes (Martinez-Garcia and van der Maarel, 2016). Despite their potential, most of the research on acidophilic microalgae has been focused on one species only: Galdieria sulphuraria (Sydney et al, 2019).…”