Characterisation of the interaction of Pseudomonas putida and Pseudomonas tolaasii with Trichoderma aggressivum

Abstract

Green mould disease is caused by Trichoderma aggressivum which colonizes mushroom compost and reduces yield. Two Pseudomonas species are associated with mushroom compost: Pseudomonas putida, which stimulates mushroom pinning, and Pseudomonas tolaasii which has a negative effect on crop production. The aim of this work was to characterize T. aggressivum -Pseudomonas interactions as these may be important factors in the development of green mould disease. P. tolaasii supernatant inhibited growth by 57% but P. putida stimulated growth of T. aggressivum by 44%. Tolaasin production was identified in P. tolaasii cultures with a peak at 96 h. Fluorescent microscopy examination of T. aggressivum hyphae revealed that exposure to P. tolaasii supernatant decreased mycelial formation while increasing the abundance of conidia. Label free proteomic analysis of changes in the abundance of T. aggressivum proteins indicated that exposure to P. tolaasii supernatant lead to an oxidative stress response and catabolic enzyme activation (mitochondrial import inner membrane translocase complex (5.7-fold), oxidoreductase (5.2fold), glucoamylase (5.1-fold)). Exposure of T. aggressivum to P. putida supernatant lead to an increase in the abundance of proteins associated with growth and development (structural constituents of ribosome (20-fold), H/ACA ribonucleoprotein complex subunit (18-fold), DNA binding and nucleosome assembly protein (5.3-fold), and prefoldin (5-fold)). These results indicate that exposure to P. putida can stimulate the growth of T. aggressivum and this interaction may be an important factor in increasing green mould disease in mushroom crops and so reducing yield.

Identification of a pathogen causing fruiting body rot of Sanghuangporus vaninii

“…As macroscopic fungi, the growth of edible mushrooms is also inhibited by Trichoderma species as aforementioned antifungal mechanism ( Velázquez-Cedeño et al, 2007 ; Abubaker, Sjaarda & Castle, 2013 ). The optimal growth environment for Trichoderma is consistent with the mycelia growth and fruiting body formation environment of most edible fungi, which leads to its infection and harm to edible fungi during the mycelium and fruiting body stages ( Kosanovic et al, 2020 ; Ponnusamy et al, 2022 ). This was confirmed by the results of both fruiting body inoculation and hyphal dual-culture experiments in the present study.…”

Dynamics of fungal and bacterial microbiome associated with green-mould contaminated sawdust substrate of Pleurotus pulmonarius (grey oyster mushroom)

“…(Rossouw & Korsten, 2016). Pseudomonas putida and P. tolassii were reported to be associated with green-mould contamination in composted substrate and reduce the yield of white button mushroom (Kosanovic et al, 2020). Genus Cedecea held the highest percentage of total quality reads from the contaminated substrate and considered as a human pathogen (Thompson & Sharkady, 2020).…”

Differential proteomic response of Agaricus bisporus and Trichoderma aggressivum f. europaeum to Bacillus velezensis supernatant

“…This paper details the testing of a supernatant derived from an environmental isolate of Bacillus velezensis as a potential biocontrol agent against green mould disease in A. bisporus cultivation. Bacteria supernatants, also known as culture filtrates, contain the microbial secretome with a range of toxins, enzymes and other products secreted by microbes that may play a role in pathogenesis (Mc Namara et al 2017;Kosanović et al 2019).…”