Evaluation of in vitro activities of extracellular enzymes from Aspergillus species isolated from corneal ulcer/keratitis

Abstract

Mycotic/fungal keratitis is a suppurative, generally ulcerative infection of the cornea. The filamentous fungi, <i>Aspergillus</i> spp. are the second leading cause of mycotic keratitis, particularly in India. <i>Aspergillus</i> spp. produce a range of extracellular enzymes that are used to break down complex molecules and used for growth and reproduction, also for survival on/in host organism. The current study was designed with an objective to screen <i>in vitro</i> extracellular enzyme activity of <i>Fusarium</i> and <i>Aspergillus</i> isolates from mycotic keratitis patients and to correlate the same as a putative virulence factor. Extracellular enzymes <i>viz.,</i> deoxyribonuclease (DNase), protease, lipase, elastase, keratinase, <i>etc.,</i> produced by <i>Aspergillus</i> have key role in keratomycosis and hence their (n = 85) <i>in vitro</i> activities were investigated. It was found that, the majority of the <i>Aspergillus</i> isolates produced protease (n = 75; 88% of 85) followed by lipase (n = 59; 69% of 85), DNase (n = 35; 41% of 85), elastase (n = 26; 31% of 85) and keratinase (n = 13; 15% of 85). The enzyme activity indices (EAI) for DNase, elastase, protease and lipase ranged between 1.01 and 1.98, whereas elastase EAI varied between 1.26 and 1.92. DNase, protease and lipase showed a maximum EAI of 1.98 and lowest EAI value of 1.01, respectively. Extracellular enzymes of <i>Aspergillus</i> spp. may have potential role in the onset and progression of keratitis.