Screening of Fungal Strains Grown in Solid-state Culture for Production of Pectinase from Coffee Husk

Abstract

Eighty percent of Vietnamese coffee production can be found in Central Highlands (Tay Nguyen). This paper describes a screening of fungi strains isolated from coffee husk waste collected in Dak Lak province, Tay Nguyen, for pectinase production. It was found that 17 different fungi strains were isolated from samples of 11 coffee farms. Among them. there were only 9 trains which could hydrolyze pectin. The diameter of the hydrolysis halo around fungi colonies in Pectinase Screening Agar Medium (PSAM) was measured as an indicator to assess the pectinase activity. Phylogenetic analysis based on 28S rRNA gene sequences showed that detected Rhizopus oryzae. Aspergillus oryzae and Hypocrea pseudokoningii were those giving the largest holo zones. Hypocrea pseudokoningii presented the best pectinase activity of 657.16 UI/g and was chosen for biomass production to collect enzyme. In a further study, effect of rice bran addition to coffee husk and moisture of culture medium on the spore yield of Hypocrea pseudokoningii were investigated. Using coffee husk medium with 23% rice bran addition and 65% moisture at ambient temperature, the highest spore yield of 9.2 x10⁸ spores/g was found after incubation for 168 hours. The fungi biomass product was dried at 40^oC for 54 hours to obtain the final moisture of 12% and spore survival of 5.9 x10⁸ spores/g.