The present study focused on isolation, identification, and evaluation of glass biodeterioration properties such as organic acid and exopolysaccharide production of fungal strain Chaetomium globosum TTHF1-3 isolated from lens of optical instrument collected at Thai Hoa, Nghe An province. | VNU Journal of Science Natural Sciences and Technology Vol. 37 No. 4 2021 104-112 Original Article Identification and Glass Biodeterioration of Chaetomium globosum TTHF1-3 Isolated from Optical Instrument at Thai Hoa Nghe An Province Cao Cuong Ngo1 2 Thi Thanh Loi Nguyen2 Thi Thu Hong Do1 The Anh Luu3 Ngoc Tung Quach2 Quyet Tien Phi2 1 Vietnam-Russia Tropical Centre Ministry of Defence 63 Nguyen Van Huyen Cau Giay Hanoi Vietnam 2 Vietnam Academy of Science and Technology 18 Hoang Quoc Viet Cau Giay Hanoi Vietnam 3 VNU Central Institute for Natural Resources and Environmental Studies 19 Le Thanh Tong Hoan Kiem Hanoi Vietnam Received 27 August 2021 Revised 02 Setptember 2021 Accepted 27 October 2021 Abstract The colonization and growth of harmful fungi on the glass surface have caused irreversible damage to optical quality. The present study focused on isolation identification and evaluation of glass biodeterioration properties such as organic acid and exopolysaccharide production of fungal strain Chaetomium globosum TTHF1-3 isolated from lens of optical instrument collected at Thai Hoa Nghe An province. Among 11 fungal isolates exhibiting the glass biodeterioration the strain TTHF1-3 caused the most glass damage with the hyphal surface coverage reaching reduction of light transmission through fungus-inoculated glass of 40-48 which corresponded to harmful grade 2 based on the ISO 9022-11 2015 criteria. Under microscopic observation the fungal strain TTHF1-3 cells showed brown or dark brown color perithecia and ascospores. Based on ITS sequence analyses the strain TTHF1-3 was found to share 100 sequence identity with that of C. globosum species available onto GenBank NCBI . Combining to morphological characteristics the fungal strain TTHF1-3 was identified as Chaetomium globosum. When incubated on MT1 medium the pH values of C. globosum TTHF1-3 culture were significantly decreased from to . In addition fungal strain TTHF1-3 was able to produce