การระบุชนิดของรา Aspergillus species และการคัดกรองสายพันธุ์ที่สร้างเอนไซม์ไคติเนสเบื้องต้น

Abstract

Aspergillus species is an important fungus in the ecosystem. It plays a role as a decomposer commonly found in the soil. Some species in this genus have antifungal properties to control plant pathogenic fungi. However, much research on Aspergillus in Thailand mainly focuses on toxicity tests. While the research on the identification and application of antagonistic microorganisms is not universal. Therefore, this research aimed to identify and describe the morphology of Aspergillus species isolated from soil in southern Thailand, and to preliminarily screen the chitinase-producing strains. Soil samples from 14 provinces in southern Thailand were collected. One hundred and six isolates of Aspergillus species were isolated by serial dilution and pour plate methods. Eighty-four non-aflatoxin-producing isolates were screened and grouped into 4 sections according to the color of the conidial head, and characteristics of vesicles and phialides. Eleven species of Aspergillus species namely A. aculeatinus (9 strains), A. brunneoviolaceus (2 strains), A. flavipes (4 strains), A. floridensis (13 strains), A. niger (19 strains), A. terreus (7 strains), A. neoniger (13 strains), A.trinidadensis (2 strains), A. unguis (3 strains), A. tubingensis (11 strains) and A. vadensis (1 strain) were identified using the nucleotide sequences of the internal transcribed spacers (ITS1-5.8-ITS2) of ribosomal DNA and calmodulin (CaM) genes with the primers pairs ITS1/ITS4 and Cmd5/Cmd6, respectively. Eighty-two strains of the isolated Aspergillus species were detected to produce chitinase on the chitinase detection medium. Most of them were Aspergillus species in section Nigri and Terrei. All 82 strains of Aspergillus species were promising antagonists against plant pathogenic fungi for further screening of other antagonistic properties.