Open AccessMulti‐target and medium‐independent fungal antagonism by hydrolytic enzymes in Paenibacillus polymyxa and Bacillus pumilus strains from barley rhizosphere
Author(s) -
Nielsen Preben,
Sørensen Jan
Publication year - 1997
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.1997.tb00370.x
Subject(s) - biology , paenibacillus polymyxa , rhizosphere , antagonism , bacillus pumilus , bacillus (shape) , botany , bacillaceae , microbiology and biotechnology , paenibacillus , bacillales , bacteria , biochemistry , bacillus subtilis , genetics , receptor , 16s ribosomal rna
Glucanolytic bacteria from barley rhizosphere soil were isolated by a procedure selecting for isolates with β‐glucosidase activity. Almost all isolates were fast‐growing, Gram‐positive rods. Sixteen out of 100 isolates showed in vitro fungal antagonism against widely different plant‐pathogenic microfungi ( Aphanomyces cochleoides , Pythium ultimum and Rhizoctonia solani ). The 16 isolates shared a characteristic profile of cell‐wall‐degrading enzymes, comprising glucanolytic (cellulase, mannanase and xylanase) and proteolytic enzymes. This enzyme profile was not observed in any of the non‐antagonistic isolates and may thus be useful in selection protocols for fungal antagonists producing fungal cell‐wall‐degrading enzymes. The antagonistic isolates were identified as Paenibacillus ( Bacillus ) polymyxa (2 strains) and Bacillus pumilus (13 strains), Bacillus sp. (1 strain). Both P. polymyxa isolates and a subgroup of 4 B. pumilus isolates showed a medium‐independent antagonism as tested against A. cochleoides in four different media. This was apparently related to constitutive production of cell‐wall‐degrading enzymes ( P. polymyxa ) or induction of a repertoire of enzymes substituting for each other in different media ( B. pumilus ). Despite different strategies of enzyme production in the media, both the P. polymyxa and B. pumilus strains demonstrate a multi‐target and medium‐independent type of fungal antagonism, which is promising for application in biological control.