Table 6.

A summary of biological pretreatments applied for numerous applications.

Bioproducts	Natural Fibres	Type of Microbes/Enzymes	Hydrolysis Conditions	Yield Improvement/Product Properties	References
Biohydrogen	Corn stover	Clostridium cellulolyticum and hydrogen fermentation bacteria	20 mL of medium, 5% (v/v) inoculum, 10 g L−1 carbon source, at 37 °C for 96 hrs	40.3 L H2 kg−1 TS *	[79]
Bioethanol	Corn stover	Ceriporiopsis subvermispora	28 °C for 18 days	57.8% yield increased	[107]
	Corn stover	Ceriporiopsis subvermispora	28 °C for 35 days	66.6% yield increased	[107]
	Potato and cassava peel	Gloeophyllum sepiarium and Pleurotus ostreatus	28 °C for 7 days	26% yield increased	[108]
	Straw	Neosartorya fischeri–Myceliophthora thermophila and Aeromonas hydrophila–Pseudomonas poae	30–55 °C for 6 days	7-fold yield increased	[109]
	Corn stover	Irpex lacteus	28 °C for 42 days	66.9% yield increased	[110]
	Corn stalks		28 °C for 28 days	82% yield increased	[111]
Biomethane	Wheat straw	Trametes versicolor	Laccase at 500 U/L, 25 °C for 6 days	10–18% yield increase	[96]
	Cassava	Yeast and cellulolytic bacteria	100 mL of PCS medium, at 55 °C for 12 h	96.6% yield increased	[112]
	Microalgae	Enzyme mix (cellulase, glucohydrolase and xylanase)	1% enzyme mix, 37 °C for 24 hrs	15% yield increased	[113]
	Sawdust	Methanobrevibacter thaueri MB-1, Methanosarcina acetivorans MB-2, and Methanococcus voltae MB 3.	60 °C for 6 days	92.2% yield increased	[114]
Biosugar	Corn stover	Ceriporiopsis subvermispora	28 °C for 5–7 days	57–67% yield increase	[107]
	Silver grass	Bacillus, Pseudomonas, Exiguobacterium, and Aeromonas	37 °C for 7 days	2.2-fold yield increased	[115]
	Sugarcane bagasse	Ceriporiopsis submervispora	27 °C for 60 days	47% yield increased	[116]
	Sawdust	Pleurotus pulmonarius	28 °C for 30 days	94.8% yield increased	[117]
	Paddy straw	Pleurotus florida	25–29 °C for 28 days	75.3% yield increased	[118]
	Rice straw	Pholiota adiposa	25 °C for 120 h	716 mg g−1 *	[119]
		Pholiota adipose and Armillaria gemina	27 °C for 45 days	74.2% yield increased	[120]
	Populus tomentiglandulosa	Armillaria gemina SKU2114	30 °C for 48 h	62% yield increased	[121]
Nanocellulose	Eucalyptus	Endoglucanase and cellobiohydrolase	7 pH, 50 °C for 48 h	20 nm diameter, >500 nm length	[122]
	Wood fibre	Endoglucanase	4.8 pH, 50 °C for 2 h	5–30 nm diameter	[123]
	Orange residues	ß-glucosidase	4 pH, 50 °C for 48 h	180 nm diameter, 1.3 mm length	[124]
	Sugarcane bagasse	ß-glucosidase and endoglucanase	5 pH, 50 °C for 24 h	14–18 nm diameter, 195–250 nm length	[125]
	Maple pulp	Cellic CTec 2 and Cellic HTec 2 (commercial enzymes)	4.8 pH, 50 °C for 72 h	5–10 nm diameter, 1 μm length	[126]
	Cotton linters	Cellulase	5 pH, 55 °C for 24 h	35 nm diameter, 0.3 mm length	[127]

* The highest yield obtained.