Nature and Science 2012;10(12) http://www.sciencepub.net/nature http://www.sciencepub.net/nature naturesciencej@gmail.com 265 Screening and Production of β-galactosidase by Trichoderma species. Akinola Gbemisola Elizabeth, Adebayo-Tayo Bukola, Olonila Omolola Toyin Department of Microbiology, University of Ibadan, Ibadan, Oyo state, Nigeria < bukola_tayo@yahoo.com > <gbemiakinola@yahoo.com > Abstract: Twelve Trichoderma strains (Trichoderma reesei, Trichoderma harzarium, Trichoderma viride, Trichoderma longibrachiatum, Trichoderma asperellum, Trichoderma arundinaceum, Trichoderma konnigii, Trichoderma pseudokonnigii, Trichoderma ciroviride, Trichoderma fertile, Trichoderma polysporum and Trichoderma crassum) were isolated from soil samples collected from different locations in Ibadan metropolis. Among the strains Trichoderma crassum (12.6%) has the highest frequency of occurrence. All the isolates were screened for β–galactosidase production using X-gal (5-bromo-4-chloroindolyl-β-D-galactopyranoside) and IPTG solution as an inducer. Six isolates were selected as the best producer of β–galactosidase. β–galactosidase production ranged from 0.3476 - 2.2369 U/ml in which Trichoderma crassum has the highest production. On submerged fermentation, static condition gave a profound increase in β-galactosidase production. The best yield of β-galactosidase production was obtained at 35 o C, pH 4, Tween80 at 0.15ml concentration and 6 days of incubation. Among the carbon and nitrogen sources tested manitol and casein supported β–galactosidase production (2.7666 - 6.9888 U/ml) by Trichoderma crassum. [Akinola GE, Adebayo-Tayo BC, Olonila OT. Screening and Production of β-galactosidase by Trichoderma species. Nat Sci 2012;10(12):265-270]. (ISSN: 1545-0740). http://www.sciencepub.net/nature . 40 Keywords: β-galactosidase; Trichoderma; IPTG; Temprature; pH 1. Introduction Trichoderma is a cosmopolitan organism in soils and on decaying wood and vegetable matter. It belongs to the family Hypocreacae. They belong to an aggregate of Deuteromycetes species whose teleomorphs belong to the Ascomycetes. Trichoderma is a fungal genus first proposed by Persoon on the basis of material collected in Germany (Persoon, 1794). Species of Trichoderma are fungi that are present in substantial numbers in many regions of the world. They are frequently dominant components of the soil microflora in widely varying habitats. This may be attributable to the diverse metabolic capability of Trichoderma species and their aggressively competitive nature (Samuels, 1996). Strains within this genus include a wide spectrum of evolutionary solutions that range from very effective soil colonizers with high biodegradation potential to non-strict plant symbionts that colonize the rhizosphere. Species concepts within Trichoderma are very wide, which has resulted in the recognition of many intraspecific groups. Some groups of biotypes within this group are able to antagonize phytopathogenic fungi by using substrate colonization, antibiosis and or mycoparasitism as the main mechanisms. This antagonistic potential is the basis for effective applications of different Trichoderma strains as an alternative to chemical control against a wide set of fungal plant pathogens (Harman and Bjorkman, 1998). Recently, (Szekeres et al., 2004) have reviewed antagonisitc metabolites produced by Trichoderma spp. The metabolites are linear, amphipathic polypeptides, namely, peptaibols and peptabiotics. They also discussed the physio- chemical and biological properties of these antibiotics compounds which included the disruption of lipid membranes, anti-microbial activities and induction of plant resistance. β-galactosidase or β-D-galactoside- galactohydrolase is used industrially to obtain the hydrolyzed lactose from milk and milk whey for utilization in bakery products, ice creams, animal feed and as a sugar source for several fermentation products. Monosaccharides derived from hydrolysis are highly soluble and usually prevent the crystallization of the remaining lactose. Enzymatic hydrolysis of lactose from milk and milk whey is also desirable for lactose-intolerant individuals (Greenberg and Mahoney, 1981). 2. Material and Methods Collection of Samples Soil samples were collected aseptically at a depth of 2cm from three different locations in Ibadan: Cocoa Research institute of Nigeria, University of Ibadan Botanical Garden and a decayed wood sample in Microbiology Department, University of Ibadan. The samples were conveyed to the laboratory in sterile polythene bags for further analysis. Isolation and identification of Trichoderma species from collected samples. Serial dilution of the collected samples was carried out (Olutiola et al.2000) and 1ml of the diluents was pour plated on Potato Dextrose agar