Microbial keratinase and the bio-economy: a three-decade meta-analysis of research exploit

Abstract

Microbial keratinase research has been on an upward trajectory due to the robustness and efficiency of the enzyme toward various green technological processes that promote economic development and environmental sustainability. A compendium of research progression and advancement within the domain was achieved through a bibliometric study to understand the trend of research productivity, scientific impacts, authors' involvement, collaboration networks, and the advancement of knowledge gaps for future research endeavours. A three-decade (1990 to 2019) scholarly published articles were retrieved from the web of science database using a combination of terms "keratinas* or keratinolytic proteas* or keratinolytic enzym*", and subsequently analyzed for bibliometric indicators. A collection of 330 peer-reviewed, research, articles were retrieved for the survey period and authored by 1063 researchers with collaboration index of 3.27. Research productivity was most in 2013 with total research output of 28 articles. The top three authors' keywords were keratinase, keratin and protease with a respective frequency of 188, 26 and 22. India, China and Brazil ranked top in terms of keratinase research outputs and total citation with respective article productivity (total citations) of 85 (1533), 57 (826), and 36 (764). This study evaluated the trend of keratinase research outputs, scientific impact, collaboration networks and biotechnology innovations. It has the potentials to influence positively decision making on future research direction, collaborations and development of products for the bio-economy.

Novel recombinant keratin degrading subtilisin like serine alkaline protease from Bacillus cereus isolated from marine hydrothermal vent crabs

“…To overcome the risk associated with the degradation of keratin substrates, the microbial keratinases are studied extensively in bio-cycling of agro-industrial wastes in cost-effective and eco-friendly ways 15 . Keratinase based formulations like Valkerase, Versazyme, CIBENZA, DP100 and FEED-0001 are useful for the improvement of the nutritional values of animal feeds 16 .…”

Structure, Application, and Biochemistry of Microbial Keratinases

“…Studies have shown that diverse keratinases with different molecular weights, optimal pH values, and optimal temperatures are produced by microorganisms. Most microbial keratinases are secreted into the extracellular matrix in the presence of keratin or keratin-containing substrates ( Vidmar and Vodovnik, 2018 ; Nnolim and Nwodo, 2021 ). Some microorganisms are able to produce extracellular and intracellular keratinases simultaneously.…”

“…In addition, as keratin degradation is a complicated step, sample isolation and enriching steps are important to make sure that the desired strains are sustained. Many keratinase-producing strains have been isolated and identified from the environment ( Nnolim and Nwodo, 2021 ).…”

“…Quite a few reports have shown that keratinolytic actinobacteria can be isolated from different environment. 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 ).…”

“…As keratin does not accumulate in nature, microorganisms are playing the major role in its degradation and recycling. Therefore, keratinous wastes threatening the environment can be converted into value-added products by using microbial treatment ( de Menezes et al, 2021 ; Nnolim and Nwodo, 2021 ). Extensive studies have been carried out to search suitable microorganisms and obtain optimized processes to make full use of keratinous wastes ( Gradišar et al, 2000 ; Sangali and Brandelli, 2000 ; Kim et al, 2001 ; Rai and Mukherjee, 2011 ).…”