Abstract/Details

Adhesion properties and cell surface characteristics of the entomopathogenic fungus <i>Beauveria bassiana</i>: A link between morphology and virulence


2005 2005

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Abstract (summary)

The entomopathogen Beauveria bassiana produces three distinct in vitro, single cell propagules: aerial conidia, blastospores and submerged conidia. Atomic force microscopy (AFM) was used to visualize the surface of aerial conidia and confirmed the presence of a rodlet layer that was absent from the surface of both blastospores, which were smooth, and submerged conidia, which appeared coarse. Interfacial free energies of interaction and hydrophobicity indicies, derived from contact angle data, and hydrocarbon partitioning revealed differential properties of the three propagules regarding cell surface hydrophobicity ranging from strongly hydrophobic (aerial conidia) to hydrophilic (blastospores). Adhesion studies with fluorescently labeled cells suggested that (1) aerial conidia bound better to hydrophobic surfaces, (2) blastospores bound better to hydrophilic surfaces, and (3) submerged conidia bound equally well to both types of surfaces. The effective surface charge (zeta potential) of the three single cell propagules was predominantly positive at low pH (pH 3-4) decreasing to negative values at higher pH values (pH 6-8). Conidial surface charge varied the most with respect to pH (+22 mV to -47 mV), while submerged conidia varied moderately (+7 mV to -13.4 mV) and the blastospores showed minor variation (+ 3.2 mV to -4.65 mV). The gene for a beauverial hydrophobin (bhd1) was identified from a suppression-subtracted library generated from cells grown in the presence of insect cuticle as opposed to glucose. Real-time, reverse transcriptase PCR of two Beauveria bassiana specific hydrophobins and a hydrophobin like protein (bhd1, bhd2 and bsn ) showed that bhd1 mRNA levels were relatively high in most cell types analyzed, with the highest abundance in submerged conidia. Transcript for bhd2 was detected primarily in aerial conidia and submerged conidia, whereas transcript for bsn was not detected under the conditions tested. A SDS insoluble/TFA soluble constituent of the cell wall of B. bassiana conidia was identified as bhd2 by peptide mass fingerprinting.

Indexing (details)


Subject
Microbiology;
Molecular biology
Classification
0410: Microbiology
0307: Molecular biology
Identifier / keyword
Biological sciences; Beauveria bassiana; Entomopathogenic; Fungus
Title
Adhesion properties and cell surface characteristics of the entomopathogenic fungus <i>Beauveria bassiana</i>: A link between morphology and virulence
Author
Holder, Diane J.
Number of pages
117
Publication year
2005
Degree date
2005
School code
0070
Source
DAI-B 66/09, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780542351921, 0542351927
Advisor
Keyhani, Nemat O.
University/institution
University of Florida
University location
United States -- Florida
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3192400
ProQuest document ID
304995583
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304995583
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