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Applied and Environmental Microbiology, September 2000, p. 4084-4090, Vol. 66, No. 9
Istituto Tossine e Micotossine da Parassiti
Vegetali, CNR, 70125 Bari,1 Dipartimento
Scienze Chimico-Agrarie, Facoltà di Agraria, Università
"Federico II," 80055 Portici (Napoli),2
Istituto di Industrie Agrarie (Microbiologia),
Facoltà di Agraria di Perugia, S. Costanzo, 06126 Perugia,3 and Dipartimento Protezione
delle Piante e Microbiologia Applicata, Facoltà di Agraria di
Bari, 70125 Bari,4 Italy
Received 9 March 2000/Accepted 16 June 2000
Sourdough lactic acid bacteria were selected for antifungal
activity by a conidial germination assay. The 10-fold-concentrated culture filtrate of Lactobacillus plantarum 21B grown in
wheat flour hydrolysate almost completely inhibited Eurotium
repens IBT18000, Eurotium rubrum FTDC3228,
Penicillium corylophilum IBT6978, Penicillium
roqueforti IBT18687, Penicillium expansum IDM/FS2, Endomyces fibuliger IBT605 and IDM3812, Aspergillus
niger FTDC3227 and IDM1, Aspergillus flavus FTDC3226,
Monilia sitophila IDM/FS5, and Fusarium
graminearum IDM623. The nonconcentrated culture filtrate of
L. plantarum 21B grown in whole wheat flour hydrolysate had similar inhibitory activity. The activity was fungicidal. Calcium propionate at 3 mg ml
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Purification and Characterization of Novel Antifungal Compounds
from the Sourdough Lactobacillus plantarum Strain
21B
1 was not effective under the same
assay conditions, while sodium benzoate caused inhibition similar to
L. plantarum 21B. After extraction with ethyl acetate,
preparative silica gel thin-layer chromatography, and chromatographic
and spectroscopic analyses, novel antifungal compounds such as
phenyllactic and 4-hydroxy-phenyllactic acids were identified in the
culture filtrate of L. plantarum 21B. Phenyllactic acid was
contained at the highest concentration in the bacterial culture
filtrate and had the highest activity. It inhibited all the fungi
tested at a concentration of 50 mg ml
1 except for
P. roqueforti IBT18687 and P. corylophilum
IBT6978 (inhibitory concentration, 166 mg ml
1). L. plantarum 20B, which showed high antimold activity, was also
selected. Preliminary studies showed that phenyllactic and 4-hydroxy-phenyllactic acids were also contained in the bacterial culture filtrate of strain 20B. Growth of A. niger FTDC3227
occurred after 2 days in breads started with Saccharomyces
cerevisiae 141 alone or with S. cerevisiae and
Lactobacillus brevis 1D, an unselected but acidifying
lactic acid bacterium, while the onset of fungal growth was delayed for
7 days in bread started with S. cerevisiae and selected
L. plantarum 21B.
*
Corresponding author. Mailing address: Dipartimento
Protezione delle Piante e Microbiologia Applicata, Facoltà di
Agraria di Bari, via Amendola 165/a, 70125 Bari, Italy. Phone: 39 0805442949. E-mail: gobbetti{at}unipg.it.
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