Table 2.

Overview of enzymes and organic acids produced from different microorganisms

Microorganisms			Enzyme activity/ Production parameters	Reference
Enzymes	Cellulase	Aspergillus niger Saccharomyces cerevisiae	↑ with substrate conc. (up to 3%)	Amaeze et al. (2015)
	Xylanase	Bacillus pumilus SV-85S	Xylanase activity was optimum at 50 ºC, pH 6 and metal ions KCl, MnCl2 and CaCl2 enhanced the activity	Nagar et al. (2012)
	Pectinase	Penicillium chrysogenum	Highest at incubation period of 48 h (220.30 mg−1 protein) and further decreased with increasing incubation period	Okafor et al. (2010)
Organic acids	Citric acid	Aspergillus foetidus ACM 3996	16.1 g/100 g (62.4%) yield under conditions, 70% initial moisture, 30 ºC, incubation 4 days and 3% methanol	Tran and Mitchell (1995)
	Citric acid	Yarrowia lipolytica NCIM 3589	202.35 g/kg under conditions, 70.71% initial moisture content, KH2PO4 0.64% (w/w), Na2HPO4 0.69% (w/w) and 0.34% (w/w) yeast extract	Imandi et al. (2008)
	L ( +) Lactic acid	Rhizopus oryzae NRRL 395	103.69 mg/g yield under optimized conditions (67.53% w/w moisture content, 32.2 ºC, pH 5.6, inoculation size 1 × 107 spores/g and 3 days incubation period)	Zain et al. (2021)
	Lactic acid	Lactobacillus delbrueckii	54.97 g/L (79%) yield under optimized conditions, 40 ºC, pH 6, inoculation size 5%, initial sugar concentration 70 g/L and 5% yeast extract (nitrogen source)	Abdullah and Winaningsih (2020)
	Succinic acid	Escherichia coli AFP 184	6.26 g/L yield under conditions, 37 ºC, pH 6.6–6.7, inoculation size 5 mL, incubation for 24 h at 200 rpm	Jusoh et al. (2014)