The herbicide paraquat alters growth and melanin production on the Cryptococcus neoformans/Cryptococcus gattii species complex

• Published in: Canadian journal of microbiology Vol. 68; no. 7; pp. 493 - 499
• Main Authors: Castelo-Branco, Débora de Souza Collares Maia, Rocha, Maria, Oliveira, Jonathas Sales de, Dos Santos Araújo, Géssica, Martins, Daniel, Garcia, Lana, Cordeiro, Rossana de Aguiar, Sidrim, José J C, Pereira Neto, Waldemiro, Guedes, Glaucia Morgana de Melo, Brilhante, Raimunda, Rocha, Marcos Fábio Gadelha
• Format: Journal Article
• Language: English
• Published: Canada NRC Research Press 01.07.2022; Canadian Science Publishing NRC Research Press
• Subjects: Agricultural research; Antifungal activity; Antioxidants; Ascorbic acid; Biofilms; Cell membranes; Chemical properties; Control; Cryptococcus; Cryptococcus neoformans; Dichlorides; Dihydroxyphenylalanine; Evaluation; Exposure; Fungal infections; Fungi; Fungicides; Glutathione; Herbicides; Levodopa; Melanin; Microbial mats; Microorganisms; Minimum inhibitory concentration; Paraquat; Soil microbiology; Soil microorganisms; Yeasts; Brazil
• ISSN: 0008-4166; 1480-3275
• DOI: 10.1139/cjm-2021-0362

Paraquat (PQ) is a free-radical producing herbicide that affects cell membranes and can upset the environmental balance of microorganisms present in soil, such as Cryptococcus spp. This study aimed to evaluate the in vitro activity of PQ against Cryptococcus spp. in planktonic and biofilm forms, as well as the protective effect of antioxidant agents against the antifungal effect of PQ and the kinetics of melanin production in response to PQ. Susceptibility to PQ was evaluated by the microdilution. Cryptococcus sp. strains exposed to PQ were grown in media with ascorbic acid (AA) and glutathione (GSH). Melanin production was assessed in the presence of L-dopa + PQ. The minimum inhibitory concentration (MIC) of PQ against Cryptococcus spp. ranged from 8 -256 μg/mL. Furthermore, PQ reduced biofilm formation. AA and GSH restored the fungal growth of Cryptococcus spp. exposed to PQ. In addition, L-dopa + PQ delayed melanin production by 24 and 48 hours for C. deuterogattii and C. neoformans sensu lato, respectively, suggesting that PQ induces a fitness trade off in melanin production. Taken together, our data suggest that antifungal effect of PQ against Cryptococcus spp. exerts a possibly selective pressures interfering with biofilm formation and melanin production by these yeasts.