Enhancement of fermentative hydrogen production from Spirogyra sp. by increased carbohydrate accumulation and selection of the biomass pretreatment under a biorefinery model

Abstract

In this work, hydrogen (H) was produced through the fermentation of Spirogyra sp. biomass by Clostridium butyricum DSM 10702. Macronutrient stress was applied to increase the carbohydrate content in Spirogyra, and a 36% (w/w) accumulation of carbohydrates was reached by nitrogen depletion. The use of wet microalga as fermentable substrate was compared with physically and chemically treated biomass for increased carbohydrate solubilisation. The combination of drying, bead beating and mild acid hydrolysis produced a saccharification yield of 90.3% (w/w). The H production from Spirogyra hydrolysate was 3.9 L H L, equivalent to 146.3 mL H g microalga dry weight. The presence of protein (23.2 ± 0.3% w/w) and valuable pigments, such as astaxanthin (38.8% of the total pigment content), makes this microalga suitable to be used simultaneously in both food and feed applications. In a Spirogyra based biorefinery, the potential energy production and food-grade protein and pigments revenue per cubic meter of microalga culture per year was estimated on 7.4 MJ, US $412 and US $15, respectively, thereby contributing to the cost efficiency and sustainability of the whole bioconversion process.

Biodiesel production through algal cultivation in urban wastewater using algal floway

“…Algae assimilate nutrients by biosorption and utilize it for its metabolic activities and store excess energy in the form of lipids, carbohydrates and proteins. Depending on algae type, culture method and nutrient stress algae are known to change their form of stored energy (Pinto et al, 2018). Both macro and microalgae biomass can be a potential feedstock for third generation biofuels (Tamilarasan et al, 2018).…”

Microalgal Systems for Wastewater Treatment: Technological Trends and Challenges towards Waste Recovery

“…Biohydrogen can be produced by microalgae or cyanobacteria either by biophotolysis [115,116] or by using microalgal biomass as a substrate for anaerobic bacteria in the dark [117][118][119][120], either using Enterobacter aerogenes and Clostridium butyricum [121]. There are reports of Chlamydomonas reinhardtii biomass being hydrolyzed to produce 37.1 mmol H2 L −1 [122], while Nannochloropsis sp.…”

Systematic review and perspective on the progress of algal biofuels

“…Spirogyra sp. can produce 146.3 mL H2/g algae [58]. In addition to produce hydrogen from one species of algae, it seems that mixing several kinds of algae may have a better hydrogen yield.…”