Biotechnological Production of Polyhydroxyalkanoates: A Review on Trends and Latest Developments

Table 1

Waste of various origins as substrate with the treatment applied and resulting in possible constituents of treated waste and percentage of maximum PHA obtained.

Substrate	Treatment applied	Possible constituents	Microorganisms	Maximum PHA produced	References
Sugarcane molasses	Acidogenic fermentation	VFAs	Glycogen accumulating organisms	0.47–0.66 C-mol PHA/C-mol of total carbon	[28]
				56–70 mol-% 3HB,
				13–43 mol-% 3HV,
				1–23 mol-% 3HHx,
				0–2 mol-% 3H2MB,  and 3H2MV
Cassava starch wastewater	Acidogenic fermentation	Acetate, butyrate acids, propionate, pH-5.3, and high COD value.	Cupriavidus sp. KKU38	PHB; 85.53% of CDW	[52]
Sugar refinery waste (cane molasses)	Acid treatment and activated charcoal	Carbohydrate (4%)	Pseudomonas aeruginosa	PHB; 62.44% of CDW	[53]
Cynodon dactylon grass and syzygium cumini seed;	Pulverization followed by hydrolysis	Glucose	SP-Y1 and Ralstonia eutropha	SP-Y1 (PHB)	[54]
				H.S
				26.76% of CDW
				H.G
				41.7% of CDW
				R. eutropha (PHB)
				H.S
				42.2% of CDW
				H.G
				28.97% of CDW
Milk and icecream wastewater	Acidogenic fermentation	VFAs	Activated sludge	0.25 kg PHA/kg of COD	[11]
Palm oil mill effluents	Acidogenic fermentations	Acetate, propionate, and butyrate	Ralstonia eutropha JMP 134	At 20th and 40th hr	[55]
				0.75 g PHA/g CDW
				At 40th and 60th hr
				0.41 g PHA/g CDW
Rice straw	Acidic treatment	Pentose sugars and hemicelluloses	Bacillus firmus NII 0830	PHB; 89% of CDW	[56]
Seed oil of Jatropha curcas	Saponification	Oleic acid, linoleic acid, and palmitic acid	Pseudomonas oleovorans ATCC 29347	P(3HB-co-3HV); 26.06% CDW	[57]
Hemicellulosic feedstock (sugarcane bagasse)	Acid hydrolysis, boiling, precipitation, and activated charcoal	Xylose, arabinose, glucose, and acetic acids	Burkholderia cepacia IPT 048 and Bacillus sacchari IPT 101	IPT 048	[58]
				PHB; 62% of CDW
				IPT 101
				PHB; 53% of CDW
25% and 50% of vinasse (ethanol industry waste)	Activated charcoal	Sucrose, oxalate, lactate, malate, and pyruvate	Haloferax mediterranei	PHB; 70% of CDW	[59]
Paper mill wastewater	Acidogenic fermentation	VFAs	Activated sludge	PHB and PHV; 48% of SDW	[16]

HB: hydroxybutyrate, HV: hydroxyvalerate, HHx: hydroxyhexanoate, 3H2MB: 3-hydroxy-2-methylbutyrate, 3H2MV: 3-hydroxy-2-methylvalerate, PHB: poly-3-hydroxybutyrate.