Table 1.
Reaction conditions for stepwise degradation of algal biomass.
Fig 1.
Comparison of physical treatments on the efficiency of cell disruption.
Depicts the amount of protein and carbohydrates (y-axis) found in the supernatant after each disruption method (x-axis). The values are relative to the initial biomass (wt%). Carbohydrate contents are displayed in yellow (PAHBAH) and green (Anthrone). Protein contents are displayed in red (Bradford) and blue (Lowry). FrPre: French press: 5 cycles with 20 mL microalgae/water suspension (10 g L-1). Son30/5: Sonication for 30/5 min with 10 mL microalgae/water suspension (10 g L-1). GBH/GBL: Wet milling with glass beads (1 mm diameter) and high/low (10 g L-1/1 g L-1) biomass loading. MoPe: Manually grinding with mortar and pestle for 5 min. BaMi: Dry milling with steal beads (5 mm diameter). UT5/30: Ultra turrax for 5/30 min with 10 mL microalgae/water suspension (10 g L-1). n = 3.
Fig 2.
Comparison of chemical treatments on the efficiency of cell disruption.
Depicts the amount of protein and carbohydrates (y-axis) found in the supernatant after each disruption method (x-axis). The values are relative to the initial biomass (wt%). Carbohydrate contents are displayed in yellow (PAHBAH) and green (Anthrone). Protein contents are displayed in red (Bradford) and blue (Lowry). T = 100°C, V = 1.5 mL, t = 1 h, c(biomass) = 1.3 g L-1, c(HCl) = 1 mol L-1, c(NaOH) = 1 mol L-1, 800 rpm, n = 3.
Fig 3.
Schematic representation of stepwise degradation of Chlorella to characterize the cell wall.
AIR: Alcohol insoluble residue. ASC: Alcohol soluble components. AmOx: c(di-ammonium oxalate) = 20 mmol L-1, pH = 4, T = 70°C, t = 1 h. 0.1 M NaOH: c(NaOH) = 0.1 mol L-1, T = 22°C, t = 24 h. 4.4 M NaOH: c(NaOH) = 4.4 mol L-1, T = 22°C, t = 8 h. H2SO4: 72% H2SO4, T = 22°C, t = 1 h, followed by dilution with water to 4% H2SO4, T = 100°C, t = 1 h. n = 3. Neutralized supernatants were analyzed for protein (Lowry) and carbohydrate (Anthrone) content and hydrolyzed by 2 M TFA (100°C, 1.5 h, 800 rpm) for monosaccharide composition analysis using high-performance anion exchange chromatography.
Fig 4.
Stepwise degradation of algal biomass AIR.
Biomass loss (grey) after each treatment (x-axis) and measured protein (blue) and carbohydrate (green) content in the supernatant referred to initial biomass (y-axis). AmOx: c(di-ammonium oxalate) = 20 mmol L-1, pH = 4, T = 70°C, t = 1 h. 0.1 M NaOH: c(NaOH) = 0.1 mol L-1, T = 22°C, t = 24 h. 4.4 M NaOH: c(NaOH) = 4.4 mol L-1, T = 22°C, t = 8 h. H2SO4: 72% H2SO4, T = 22°C, t = 1 h, followed by dilution with water to 4% H2SO4, T = 100°C, t = 1 h. n = 3.
Fig 5.
Monosaccharide composition in TFA-hydrolyzed supernatants after subsequent treatments in stepwise degradation.
Individual sugar in the supernatant referred to initial biomass (y-axis) after each treatment (x-axis). Di-ammonium oxalate (AmOx): c(AmOx) = 20 mmol L-1, pH = 4, T = 70°C, t = 1 h. 0.1 M NaOH: c(NaOH) = 0.1 mol L-1, T = 22°C, t = 24 h. 4.4 M NaOH: c(NaOH) = 4.4 mol L-1, T = 22°C, t = 8 h. H2SO4: 72% H2SO4, T = 22°C, t = 1 h, followed by dilution with water to 4% H2SO4, T = 100°C, t = 1 h. n = 3. Neutralized supernatants were hydrolyzed by 2 mol L-1 TFA, T = 100°C, t = 1.5 h and analyzed for monosaccharide composition using high-performance anion exchange chromatography.