BioMed Research International

Review Article

Second-Generation Bioethanol from Coconut Husk

Table 4

Comparison of fermentation conditions, ethanol concentration, and yield.


Reference	Pretreatment	Fermentation strategy	Microorganisms	Conditions	Maximum Ethanol concentration (g/L or )	Ethanol yield (g ethanol/ g sugars or )

[53]	Microwave-assisted-alkaline	SSF	S. cerevisiae ATCC 36858	30°C, 150 rpm, 96 h	0.09% (w/w)	n.a.

[27]	2 steps with NaOH	SHF	S. cerevisiae	37°C, 72 h, pH 5.5.	2.28% (w/v)	Approx 85%
[27]	2 steps with NaOH	SSF	S. cerevisiae	37°C, 72 h, pH 5.5.	1.03% (w/v)	Approx 85%

[31]	Alkaline hydrogen peroxide + alkaline delignification	SSF	S. cerevisiae, P. stipitis and Z.mobilis	30°C, agitation depending on microorganism, 48 h	S. cerevisiae 8.44 g·L⁻¹ P.stipitis 9.12 g·L⁻¹ Z. mobilis 8.27 g·L⁻¹	S. cerevisiae 0.43 P.stipitis 0.40 Z. mobilis 0.42
[31]	Alkaline hydrogen peroxide + alkaline delignification	SSSF	S. cerevisiae, P. stipitis and Z.mobilis	30°C, agitation depending on microorganism, 40 h	S. cerevisiae 9.32 g·L⁻¹ P.stipitis 10.17 g·L⁻¹ Z. mobilis 8.91 g·L⁻¹	S. cerevisiae 0.45 P.stipitis 0.43 Z. mobilis 0.44

[32]	Autohydrolysis	SSF	S. cerevisiae, P. stipitis and Z.mobilis	30°C, agitation depending on microorganism, 48 h	S. cerevisiae 7.44 g·L⁻¹ P.stipitis 8.47 g·L⁻¹ Z. mobilis 7.30 g·L⁻¹	S. cerevisiae 0.44 P.stipitis 0.43 Z. mobilis 0.43
[32]	Autohydrolysis	SSSF	S. cerevisiae, P. stipitis and Z.mobilis	30°C, agitation depending on microorganism, 40 h	S. cerevisiae 7.71 g·L⁻¹ P.stipitis 8.78 g·L⁻¹ Z. mobilis 7.63 g·L⁻¹	S. cerevisiae 0.45 P.stipitis 0.44 Z. mobilis 0.45

[28]	NaOH	SHF	S. cerevisiae	150 rpm, 11 days, pH 4.5-5	5.9%	n.a.

[49]	NaOH	SHF	S. cerevisiae	30°C, 100 rpm, 9 h	7 g·L^{-1 +}	n.a.

[33]	Hydrothermal catalyzed with NaOH	SSF	S. cerevisiae, P. stipitis and Z.mobilis	30°C, agitation depending on microorganism, 48 h	S. cerevisiae 10.91 g·L⁻¹ P.stipitis 10.96 g·L⁻¹ Z. mobilis 10.81 g·L⁻¹	S. cerevisiae 0.44 P.stipitis 0.45 Z. mobilis 0.43
[33]	Hydrothermal catalyzed with NaOH	SSSF	S. cerevisiae, P. stipitis and Z.mobilis	30°C, agitation depending on microorganism, 36 h	S. cerevisiae 11.65 g·L⁻¹ P.stipitis 11.29 g·L⁻¹ Z. mobilis 11.64 g·L⁻¹	S. cerevisiae 0. 47 P.stipitis 0.46 Z. mobilis 0.47

[50]	NaOH	SHF	S. cerevisiae strains Ethanol Red and GSE16- T18	35°C, 100 rpm, 103 h, pH 5.5	3.73% (v/v)	0.43

[54]	Acidified aqueous glycerol	SSF	S. cerevisiae Hansen 2055	37°C, 150 rpm, 72 h	8.97 g·L⁻¹	n.a.
[54]	Aqueous glycerol	SSF	S. cerevisiae Hansen 2055	37°C, 150 rpm, 72 h	2.66 g·L⁻¹	n.a.

[48]	NaOH	SHF	S. cerevisiae GSE16- T18	35°C, 100 rpm, 72 h, pH 5.5	4.33% (v/v)	0.41

n.a.: not available or not present; with 50 g· of initial glucose instead of the 22.8 g· reported from the hydrolysis. No explanation for the rise of sugar concentration was found. ⁺ with aprox 16 g· of initial glucose instead of the 8.7 g· reported from the hydrolysis. No explanation for the rise of sugar concentration was found.