Molecular strategies to increase keratinase production in heterologous expression systems for industrial applications

Structure, Application, and Biochemistry of Microbial Keratinases

“…Some actinobacteria are able to produce thermally stable keratinases which have great potential to be widely used in industry ( Nnolim and Nwodo, 2021 ). The detail introduction of keratinase-producing microorganisms have been described in several reviews ( Papadopoulos, 1989 ; Onifade et al, 1998 ; Korniłłowicz-Kowalska and Bohacz, 2011 ; McKittrick et al, 2012 ; Sahni et al, 2015 ; Kanoksilapatham and Intagun, 2017 ; Pahua-Ramos et al, 2017 ; Verma et al, 2017 ; Kowalczyk et al, 2018 ; Li et al, 2018 ; Vidmar and Vodovnik, 2018 ; Li, 2019 ; Hassan et al, 2020 ; Kumar, 2020 ; Qiu et al, 2020 ; Yahaya et al, 2021 ).…”

“…Recombinant techniques are applied to the production of keratinases ( Descamps et al, 2003 ; Liu et al, 2013b ; Fang et al, 2014 ; Yong et al, 2020 ; Yahaya et al, 2021 ). This method is particularly meaningful for keratinases that are produced by pathogenic microorganisms ( Muhammed et al, 2021 ) and the mutants with an improved enzymatic activity and stability ( Zhang et al, 2020 ).…”

“…In addition to journal publications, quite a few patent literatures reported preparation, extraction, and recombinant production of keratinases. The related patents can be obtained from different resources ( Yahaya et al, 2021 ). Over 20,000 records can be obtained in google patent when keratinase was used as a searching keyword 1 .…”

Keratinases as Versatile Enzymatic Tools for Sustainable Development

“…Most keratinases are typically synthesized in the late exponential and/or in stationary phase and it is most probably related to the time needed for metabolism adaptation to the lack of nutrients in a given environment. As keratinolytic enzymes are regarded as inductive biocatalysts, their synthesis is carried out mainly in response to a keratinous substrate presence [ 18 , 44 , 46 , 72 , 73 , 74 , 75 , 76 ]. Reportedly, other protein components of microbiological media, such as tryptone, casein or yeast extract are, however, less effective kertinases inducers [ 18 , 19 , 66 , 77 ].…”

“…Many keratinolytic enzymes are active against synthetic peptides such as Z-Ala-Ala-Leu-pNA, Z-Gly-Gly-Leu-pNA, Z-Gly-Pro-Cit-pNA and Suc-Ala-Ala-Pro-Phe-pNA, corresponding to the subtilisin substrate specificity [ 22 ]. Enzymatic activity of keratinases is diverse and generally falls in the range of 10 to 18,000 U/mL [ 72 ]. However, it is worth noting that methods of keratinase activity assay are a subject of greater discussion, as there are many available [ 75 ] (see Table 4 ) and each is characterized by different advantages and disadvantages with little possibility for comparison of final results [ 19 , 74 , 79 ].…”