Table 2 Some information on the purification and characterization of microbial-derived STPs reported in recent 8 years

Alkaline serine protease

Ammonium sulfate precipitation, anion-exchange and gel permeation chromatography

32 kDa

Up to 20% (w/v) NaCl

pH 10.5, 60 °C

Ibrahim et al. 2015a

Alkaline protease

Ammonium sulphate precipitation, anion-exchange chromatography, and gel filtration

35 kDa

Up to 30% NaCl concentration

pH 8.0, 50 °C

Wu et al. 2015

Halo-alkaline serine protease

Acetone precipitation, ultrafiltration and carboxymethyl (CM) cation exchange chromatography

48–50 kDa

2.5 M NaCl, 50% of residual activity

pH 9.5, 35 °C

Ghafoori et al. 2016

Acid protease

Filtration, CM-Sepharose fast flow column, and ultrafiltration

34.5 kDa

3.5 M NaCl, maintaining 60% activity

pH 5.0, 50 °C

Lario et al. 2015

Alkalithermophilic protease

Ethanol precipitation and anion-exchange chromatography

35 kDa

2.7 M NaCl, maximal activity

pH 9.0, 55–56 °C

Abdel-Hamed et al. 2016

Alkaline serine protease

Ammonium sulfate precipitation, dialysis, and DEAE 52-cellulose column

32.3 kDa

30% NaCl concentrations, 18.1% of residual activities

pH 8.0, 40 °C

Xie et al. 2016

Alkaline protease

Ammonium sulfate precipitation, ion exchange chromatography, and gel filtration chromatography

63 kDa

Up to 4.0 M NaCl

pH 8.5, 55 °C

Mokashe et al. 2017

Alkaline protease

DEAE-Sepharose fast flow column and Sephadex G-100 column

47 kDa

0–3.0 M NaCl

pH 8.0, 50 °C

Gao et al. 2017

Alkaline protease

Ammonium sulfate precipitation, dialysis, and Äkta Avant 25 (CM-Sephadex C-50 column, Sephadex G-100 column)

29 kDa

3.0 M NaCl for 7 d, 20% of residual activities

pH 9.0, 40 °C

Gao et al. 2019

Aspartyl aminopeptidase

Ammonium sulfate precipitation, dialysis, and Äkta Avant 25 (Bio-Gel A column, HiTrap Q HP column, superose 6 column)

57 kDa

Beyond 30% of the activity in 3.0 M NaCl

pH 7.0, 50 °C

Gao et al. 2018

Neutral protease I

Ammonium sulfate precipitation, dialysis, and Äkta Avant 25 (DEAE-sephadex A-50 column), hydroxyapatite chromatography

69 kDa

3.0 M NaCl, the activity decreased by 30%

–

Gao et al. 2018

Halo-alkaline protease

Ammonium sulphate precipitation and molecular sieve chromatography

About 37 kDa

Up to 5.0 M NaCl, stable

pH 10.5, 45 °C

Kalwasinska et al. 2018

Metalloprotease

Gel filtration column (Superdex 200 pg) and a HiTrap Q FF ion exchange column

About 35 kDa

20% NaCl for 480 h, 22% of residual activities

pH 6.0–10.0, 25–40 °C

Zhang et al. 2018

Halo-alkaline protease

Ammonium sulfate precipitation, dialysis, and UNO-Q12 anion exchange column

37 kDa

NaCl concentrations (0–2.0 M)

pH 10.0, 70 °C

Daoud et al. 2018

Alkaline serine protease

Ammonium sulfate precipitation, anion exchange (DEAE-Sephadex G-50) and gel filtration (Sephadex G-50) column Chromatography

33 kDa

20% salt concentration, 48.3% residual activity

pH 10.0, 60 °C

Ibrahim et al. 2019

Alkaline serine protease

Ni–NTA Superflow column and dialysis

34 kDa

2.0 M NaCl, 49% relative activity

pH 8.0, 40 °C

Yang et al. 2020

Serine alkaline protease

Ammonium sulfate precipitation, dialysis, and Sephacryl S-200 HR column

30.3 kDa

0.5–5.0 M NaCl, maximum activity

pH 10.0, 65 °C

Ouelhadj et al. 2020

Metalloproteinase

Sephadex-250, ethanol precipitation, dialysis, and Sephadex G-200 gel permeation column

67 kDa

0–5.0 M NaCl

pH 7.0, 70 °C

Gaonkar and Furtado 2020

Alkaline serine protease

Ammonium sulfate precipitation and phenyl Sepharose 6 fast flow column

68 kDa

4.0 M NaCl (w/v), stable

pH 9.0, 70 °C

Chauhan et al. 2021

Serine protease

Ni-agarose column and his-tagged proteins

42 kDa

0.5–4.0 M NaCl, > 75% of maximal activity

pH 9.0, 45 °C

Hou et al. 2021

Halo-alkaline protease

Ammonium sulfate precipitation and phenyl Sepharose 6 fast flow column

70 kDa

2.0–4.0 M NaCl, maximal activity

pH 7.0, 50 °C

Foophow et al. 2022

Alkaline subtilisin

Ethanol precipitation, and Äkta Avant 25 (HiPrep 26/10 desalting column, S-Sepharose FF column)

27.1 kDa

Up to 5.0 M NaCl, stable and active

pH 9.0–9.5, 55 °C

Falkenberg et al. 2022

Alkaline protease

Ammonium sulfate precipitation, phenyl Sepharose 6 fast flow column, and Sephadex G-75 column

40 kDa

0.25–0.5 M NaCl, optimal catalytic performance

pH 10.5–10.0, 50 °C

Raval et al. 2022

Alkaline protease

Ammonium sulfate precipitation, phenyl Sepharose 6 fast flow column, and Sephadex G-75 column

28 kDa

0.25–0.5 M NaCl, optimal catalytic performance

pH 10.5–10.0, 50 °C

Raval et al. 2022