Production and use of microbial keratinases

Keratinaze so proteaze, ki med drugim razgrajujejo tudi na razgradnjo zelo odporne keratinske substrate. Večina jih spada v skupino ekstracelularnih serinskih proteaz ali metaloproteaz. Proizvajajo jih številne glive in bakterije, kjer prevladujeta predvsem Bacillus subtilis in Bacillus lichenformis, pogosto so izolirane tudi iz aktinomicet. Postopki biotehnološke proizvodnje se razlikujejo glede na vrsto mikroorganizma. Večinoma je v uporabi submerzna kultivacija, s keratinskim substratom kot glavnim virom ogljika in dušika. Pogosto se za optimizacijo proizvodnje dodajajo različni viri ogljika in dušika, ter kovinski ioni, ki delujejo stimulativno. Večina keratinaz je alkalnih ali nevtralnih proteaz, z temperaturnim optimumom med 40-70°C. Izolirani so bili številni sevi z široko pH in termostabilnostjo, zaradi česar so zanimive za uporabo v številnih industrijskih aplikacijah. V zadnjih letih se odkrivajo vedno nove možnosti njihove uporabe. Veliko zanimanje je za uporabo na področju razgradnje odpadkov agroživilske in usnjarske industrije, proizvodnjo bioplina, razgradnjo prionov, obdelavo tekstila, dostavo zdravil, v kozmetiki,… Biotehnološki postopki, kjer so v uporabi mikrobne keratinaze lahko tako na več načinov pripomorejo k manjši obremenitvi okolja z organskimi odpadki in proizvodnji recikliranih produktov z dodano vrednostjo.Keratinases are proteases that, among other molecules, degrade robust keratin substrates. Most of them belong to extracellular serine proteases or metalloproteases. A number of fungi and bacteria produces them. Bacillus subtilis and Bacillus lichenformis are two of the most investigated producers, but they are also often isolated from actinomycetes. Methods of biotechnological production are different for every microorganism. Submerged cultivation is most frequently used, with a keratin substrate as the main source of carbon and nitrogen. Often, various sources of carbon, nitrogen and metal ions that act stimulative are added to the medium for optimization of production. Most keratinases are alkaline or neutral proteases, with a temperature optimum between 40-70°C. Many strains with a wide pH and thermostability range were isolated, which makes them applicable in many industries. In recent years, new possibilities for their use have been discovered. There is a great interest in their use in the field of degradation of waste from the agricultural and leather industry, biogas production, prion degradation, textile processing, medicines delivery, cosmetics, ... Biotechnological procedures using microbial keratinases can in many ways contribute to reduced organic waste accumulation in the environment and the production of recycled products with added value