Trehalose and Sucrose Osmolytes Accumulated by Algae as Potential Raw Material for Bioethanol

Abstract

Currently, obtaining sustainable fuels, such as biodiesel and bioethanol, from cheap and renewable materials is a challenge. In recent years, a new approach being developed consists of producing, sugars from algae by photosynthesis. Sugar accumulation can be increased under osmotic stress (osmoregulation). The aim of this study is to show the pro-duction of sugars from algae, isolated from natural sources, and the effect of osmotic stress on fermentable sugars ac-cumulation. Strain isolation, production of sugars from each alga and the effect of osmotic stress on growth and sugar production are described. Twelve algal strains were isolated, showing growths between 0.6 and 1.8 g of biomass dry weight /L, all with production of intracellular and extracellular sugars. The strain identified as Chlorella sp. showed an increase in sugar production from 23.64 to 421 mg of sugars/g of biomass dry weight after 24 h of osmotic stress with 0.4 M NaCl. Sucrose and trehalose, both fermentable sugars, were the compatible osmolytes accumulated in response to the osmotic stress. The isolated strains are potential producers of fermentable sugars, using the photosynthetic pathway and osmotic stress

Simultaneous accumulation of neutral lipids and biomass in Nannochloropsis oceanica IMET1 under high light intensity and nitrogen replete conditions

“…Trehalose, a multifunctional molecule composing two glucose residues, is much more than a simple storage compound [6] and is now considered as a potential feedstock for bioethanol production [3]. Trehalose has been identified in a wide number of organisms, and the concentration of this molecule was only considerably lower in algae [39].…”

Differential responses to salt concentrations of lichen photobiont strains isolated from lichens occurring in different littoral zones

“…While sucrose was accumulated in Hr-Hm and Hr-Ha growing under high salinity, glycerol was synthesized in Hr-Ws. Several studies have demonstrated that the degree of halotolerance in algae is directly linked to the type of osmolyte that accumulates (Bremauntz et al 2011, and references within). In stenohaline algae, sucrose is more often accumulated in response to osmotic stress, while in euryhaline species, glycerol is more commonly synthesized to adapt to high external salinity (Reed et al 1984;Warr et al 1985;Reed 1989).…”

Osmotic Stress Effect over Carbohydrate Production in a Native Starin of <i>Scenedesmus</i> sp.

“…The samples were enriched with four culture media, according to the salinity of the site of their acquisition, BG11, BG11/saline (25 g/L) and Guillar F/2 media [12], in the culture conditions reported [1]. After replanting two times in liquid media, the algae that demonstrated the largest growth were planted in the solid culture media with 10% agar-agar.…”

“…To determine intracellular sugars, a modified Muller method was used for the extraction [1], followed by quantification through the Dubois method.…”

“…This is the case for glucose, sucrose, and trehalose which can even be fermented to produce bioethanol [1].…”