LIPOLYTIC ACTIVITY OF SOME FUNGAL SPECIES ON CASTOR OIL

• Published in: African journal of food, agriculture, nutrition, and development : AJFAND Vol. 12; no. 6; pp. 6686 - 6699
• Main Authors: Negedu, Anthony, Ameh, J.B, Umoh, V.J, Atawodi, S.E
• Format: Journal Article
• Language: English
• Published: Kenya Rural Outreach Program 01.10.2012
• Subjects: Castor; Castor oil; Composition; Deterioration; Fungi; Lipolysis; Methods; Molds (Fungi); Oil; Properties; Seeds; Nigeria
• ISSN: 1684-5358; 1684-5374

Castor seed is important because of the castor oil content (40 - 57%). The oil enjoys tremendous world demand in the pharmaceutical, paint, cosmetics, textile, leather, lubricant, chemical, plastic, fibre, automobile and engineering industries. Castor oil, aside being a renewable resource, it is biodegradable and eco-friendly. Agricultural products are natural habitats of fungi and these materials contain cellulose, hemi-cellulose, starch, oils and other complex organic compounds. The ability of the fungi to exist in these environments largely depends on their ability to produce enzymes capable of breaking down the various organic materials to provide their nutrients. Castor seeds and castor oil are good sources of nutrients for fungal growth and development. Fungi are capable of producing lipases which can hydrolyze fats or oils to fatty acids thereby increasing the free fatty acids of the produce and this is a deteriorating effect. Lipid degradation takes place when seeds or their oils are damaged by improper storage conditions or are exposed to certain microorganisms. Studies were carried out on the ability of nine fungal species namely: Aspergillus tamarii Aspergillus chevallieri , Penicillium chrysogenum , Cephaliophora irregularis , Syncephalastrum racemosum , Aspergillus flavus , Aspergillus ruber , Aspergillus terreus and Aspergillus niger to produce extracellular lipases in stationary liquid medium using quantitative and qualitative indices including, dry mycelia mass, free fatty acid and peroxide values. These studies showed that all the mould species exhibited lipolytic activity to varying levels as confirmed by formation of blue halo round the fungal colonies. The highest level of lipolytic activity (96.88% +1.12%) was produced by Aspergillus tamari. which was also characterized by highest mycelia dry yield (2.54 mg/40ml + 0.20 mg/40ml), while Cephaliphora irregularis produced the least lipolytic activity (3.10 % + 0.18%). The highest peroxide value (38.1 meq/kg + 1.17meq/kg) was obtained in the medium inoculated with Aspergillus tamarii while the least (6.20 meq/kg+0.58)meq/kg was with Aspergillus terreus after 30 days of storage. The study showed that Aspergillus tamarii and Aspergillus flavus grew well and readily caused lipolytic activity when cultured in medium containing castor oil as the only carbon source, suggesting that these fungal species contributed significantly to castor oil bio-deterioration.