title: Growth inhibition of the cyanobacterium Microcystis aeruginosa and degradation of its microcystin toxins by the fungus Trichoderma citrinoviride.
abstract: Harmful cyanobacterial blooms are recognized as a rapidly expanding global problem that threatens human and ecosystem health. Many bacterial strains have been reported as possible agents for inhibiting and controlling these blooms. However, such algicidal activity is largely unexplored for fungi. In this study, a fungal strain kkuf-0955, isolated from decayed cyanobacterial bloom was tested for its capability to inhibit phytoplankton species in batch cultures. The strain was identified as Trichoderma citrinoviride Based on its morphological characteristics and DNA sequence. Microcystis aeruginosa co-cultivated with living fungal mycelia rapidly decreased after one day of incubation, and all cells completely died and lysed after 2 days. The fungal filtrate of 5-day culture also exhibited an inhibitory effect on M. aeruginosa, and this inhibition increased with the amount of filtrate and incubation time. Conversely, green algae and diatoms have not been influenced by either living fungal mycelia or culture filtrate. Interestingly, the fungus was not only able to inhibit Microcystis growth but also degraded microcystin produced by this cyanobacterium. The toxins were completely degraded within 5 days of incubation with living fungal mycelia, but not significantly changed with fungal filtrate. This fungus could be a potential bioagent to selectively control Microcystis blooms and degrade microcystin toxins.
authors.affiliation: Botany Department, Faculty of Science, Sohag University, Sohag 82524, Egypt. Electronic address: mzakaria_99@yahoo.com.
authors.forename: Zakaria A
authors.initials: ZA
authors.lastname: Mohamed
authors.affiliation: King Khalid University, Faculty of Science, Biology Department, P.O. Box 10255, Abha 61321, Saudi Arabia; Assiut University, Faculty of Science, Botany Department, Assiut 71516, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Hashem
authors.affiliation: Assiut University, Faculty of Science, Botany Department, Assiut 71516, Egypt.
authors.forename: Saad A
authors.initials: SA
authors.lastname: Alamri
mesh_terms: D001673:Biodegradation, Environmental; D018920:Coculture Techniques; D052998:Microcystins / Q000378:metabolism*; D046931:Microcystis / Q000254:growth & development* / Q000378:metabolism; D025282:Mycelium / Q000378:metabolism; D014242:Trichoderma / Q000378:metabolism / Q000502:physiology*
chemical_list: D052998:Microcystins; C078588:microcystin
keywords: Biodegradation; Cyanobacteria; Fungi; Lysis; Microcystins