Bbmsn2 acts as a pH‐dependent negative regulator of secondary metabolite production in the entomopathogenic fungus Beauveria bassiana. (17th July 2014)

• Record Type: Journal Article
• Authors: Luo, Zhibing; Li, Yujie; Mousa, Jarrod; Bruner, Steven; Zhang, Yongjun; Pei, Yan; Keyhani, Nemat O.
• Is Part Of: Environmental microbiology. Volume 17:Number 4(2015:Apr.)
• Page Start: 1189
• Page End: 1202
• Publication Date: 2014-07-17
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12542
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Fungal secondary metabolites are chemical compounds important for development, environmental adaptation and for potential biotechnological and pharmaceutical applications. Oosporein, a red‐pigmented benzoquinone, produced by many fungal insect pathogenic <italic>B</italic><italic>eauveria</italic> spp., shows remarkable functional diversity, displaying antimicrobial, antiviral and even anti‐proliferative activities. A homologue of the <italic>msn2</italic>/<italic>seb1</italic> transcription factor was identified in a <italic>B</italic><italic>eauveria bassiana</italic> random T‐DNA insertion library. Targeted gene‐knockout of <italic>B</italic><italic>bmsn2</italic> resulted in reduced growth and increased sensitivity to Calcofluor White, H<sub>2</sub>O<sub>2</sub> and Congo Red. However, when normalized to growth at 26°C, the <italic>Δ</italic><italic>B</italic><italic>bmsn2</italic> mutant was more tolerant to high temperature (32°C) than the wild type parent. The <italic>Δ</italic><italic>B</italic><italic>bmsn2</italic> mutant also displayed a pH‐dependent growth phenotype, with little growth seen at pH < 5.0 but, better growth at alkaline conditions (pH > 8.0). Unexpectedly, a pH‐dependent deregulation of a red pigment, identified as oosporein, was seen in the <italic>Δ</italic><italic>B</italic><italic>bmsn2</italic> mutant. The <italic>Δ</italic><italic>B</italic><italic>bmsn2</italic> strain was impaired in virulence in both topical and intrahaemocoel injection bioassays against <italic>G</italic><italic>alleria mellonella</italic>. <italic>Δ</italic><italic>B</italic><italic>bmsn2</italic> proliferation in the host haemolymph and conidiation on the host cadaver was reduced. These data indicate that <italic>B</italic><italic>bmsn2</italic> acts as a negative regulator of oosporein production and contributes to virulence and growth in response to external pH in <italic>B</italic><italic>. bassiana</italic>.</p> </abstract>