Optimization of keratinolytic protease production by Purpureocillium lilacinum LPS # 876 as a sustainable management of tannery hair waste

CAVELLO, IVANA; CAVALITTO, SEBASTIÁN

THE JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION

AMER LEATHER CHEMISTS ASSOC

Lugar: Texas; Año: 2013 vol. 108 p. 300 - 310

0002-9726

Hair waste is recognized as a solid waste generated after a hair-saving unhairing process in leather technology and it is produced in large amounts in Buenos Aires province, Argentine. At the present time, the unique option for this solid waste is its disposal, which results in an environmental troublesome and a lost of money for the tanneries because of the cost of it disposal. Biodegradation of hair waste by keratinolytic microorganisms represents an alternative for bioconversion of keratin waste. This paper reports the optimization of keratinases production by Purpureocillium lilacinum LPS # 876. Firstly, one factor-at-a-time method was used to investigate the effect of nitrogen-sources, metal ions concentration in the basal mineral medium, as well as, initial pH and temperature on enzyme production. Medium composition for the keratinases production by P. lilacinum was optimized using two statistical methods: Plackett-Burman design and central composite design -combined with response surface methodology- used to optimize three significant variables: initial pH, glucose and CaCl2. The optimal conditions were determined as 7.10 g l-1 of glucose; 0.0065 mg l-1 of CaCl2 and initial pH of 5.60; at this condition the maximum keratinase yield predicted was 26.7 U ml-1. The model validation showed that it described adequately the influence of glucose and calcium concentration and initial pH on enzyme production. Production of keratinases by P. lilacinum is a less-exploited field that might represent a novel and promising biotechnological application for this microorganism.