Abstract
BackgroundArgentina’s geothermal areas are niches of a rich microbial diversity. In 2020, species of Bacillus cytotoxicus were isolated for the first time from these types of pristine natural areas. Bacillus cytotoxicus strains demonstrated the capability to grow and degrade chicken feathers with the concomitant production of proteases with keratinolytic activity, enzymes that have multitude of industrial applications. The aim of this research was to study the production of the proteolytic enzymes and its characterization. Also, feather protein hydrolysates produced during fermentation were characterized. ResultsAmong the thermotolerant strains isolated from the Domuyo geothermal area (Neuquén province, Argentina), Bacillus cytotoxicus LT-1 and Oll-15 were selected and put through submerged cultures using feather wastes as sole carbon, nitrogen, and energy source in order to obtain proteolytic enzymes and protein hydrolysates. Complete degradation of feathers was achieved after 48 h.Zymograms demonstrated the presence of several proteolytic enzymes with an estimated molecular weight between 50 and > 120 kDa. Optimum pH and temperatures of Bacillus cytotoxicus LT-1 crude extract were 7.0 and 40 °C, meanwhile for Oll-15 were 7.0 and 50 °C. Crude extracts were inhibited by EDTA and 1,10 phenanthroline indicating the presence of metalloproteases.Feather protein hydrolysates showed an interesting antioxidant potential measured through radical-scavenging and Fe3+-reducing activities. ConclusionThis work represents an initial approach on the study of the biotechnological potential of proteases produced by Bacillus cytotoxicus. The results demonstrated the importance of continuous search for new biocatalysts with new characteristics and enzymes to be able to cope with the demands in the market.
Highlights
Argentina’s geothermal areas are niches of a rich microbial diversity
It is in the Domuyo geothermal area that several strains of Bacillus cytotoxicus were isolated and characterized, a novel keratinolytic bacteria isolated for the first time from pristine environments
Bacillus cytotoxicus Oll-15 under the described fermentation conditions reached a maximum enzyme production of 14.4 ± 0.2 U·ml-1 in 24 h of incubation, while strain LT-1 reached a maximum of 16.6 ± 0.4 U·ml-1 after 33 h of cultivation
Summary
Argentina’s geothermal areas are niches of a rich microbial diversity. In 2020, species of Bacillus cytotoxicus were isolated for the first time from these types of pristine natural areas. Bacillus cytotoxicus strains demonstrated the capability to grow and degrade chicken feathers with the concomitant production of proteases with keratinolytic activity, enzymes that have multitude of industrial applications. The growing intensity of this industrial activity leads to the accumulation of this kind of hard-to-degrade feather waste and causes a complete need for its disposal. The production of feather meal by chemical treatment at high pressure can partially hydrolyze this recalcitrant protein, increasing the digestibility but reducing the amount of certain thermolabile amino acids, limiting its use as a livestock feed additive [1]. The bioconversion of feathers by keratinolytic microorganisms results in the production of enzymes such as keratinases and proteases, microbial biomass, and protein hydrolysates (with amino acids and peptides with bioactive properties). Keratinases and proteases are very useful for many industrial applications, especially on detergent industry, leather and textile industry, prion decontamination, and certain medical and cosmetic applications [1, 2]
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