Ability of Moderately Halophilic Bacteria to Control Grey Mould Disease on Tomato Fruits

• Published in: Journal of phytopathology Vol. 156; no. 1; pp. 42 - 52
• Main Authors: Sadfi-Z.ouaoui, N, Essghaier, B, Hajlaoui, M.R, Fardeau, M.L, Cayaol, J.L, Ollivier, B, Boudabous, A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 2008; Blackwell Publishing Ltd; Blackwell
• Subjects: bacterial characterization; Bacterial plant pathogens; biocontrol; Biological and medical sciences; biological control; Botrytis cinerea; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; grey mould; halophilic bacteria; hydrolytic enzymes; Phytopathology. Animal pests. Plant and forest protection; postharvest diseases; tomatoes; Tunisia; Africa; Chitinase; Planococcus; Botrytis cinerea; Bacillus subtilis; Ribosomal DNA; Postharvest; Triacylglycerol lipase; Esterases; Bacillaceae; Planococcaceae; Fungi; tomatoes; Bacillales; bacterial characterization; Halophily; Dicotyledones; Angiospermae; Lycopersicon esculentum; Micrococcales; Bacteria; Fungi Imperfecti; Solanaceae; biocontrol; Human; Halotolerance; Amylase; Enzyme; halophilic bacteria; postharvest diseases; Carboxylic ester hydrolases; Strain; Glycosylases; Peptidases; Soils; Vegetable crop; Glycosidases; grey mould; Hydrolases; Isolate; hydrolytic enzymes; Spermatophyta
• ISSN: 0931-1785; 1439-0434
• DOI: 10.1111/j.1439-0434.2007.01329.x

Tomato is one of the leading crops in Tunisia in terms of weight consumed (20 kg/per person/year). Preserving the quality of the fruit from field to consumer is essential to successful marketing. Grey mould rot induced by Botrytis cinerea is an important cause of postharvest loss depending on season and handling practices. We describe here the ability of halotolerant to moderately halophilic bacteria isolated from different Tunisian Sebkhas (hypersaline soils) to protect fresh-market tomato fruits from B. cinerea. The tomatoes tested were at two different stages of ripening, (i) mature-green and (ii) red. Six strains significantly reduced growth of the pathogens from 67% to 87%. The effectiveness of these antagonists was also confirmed on green tomatoes; in which the fruit rot protection rate ranged from 74% to 100%. The antagonists were characterized by morphological, biochemical and physiological tests as well as 16S rDNA sequencing. The halotolerant effective isolates were identified as belonging to one of the species Bacillus subtilis (M1-20, J9) or B. licheniformis (J24). One effective moderately halophilic isolate (M2-26) was identified as Planococcus rifietoensis. These strains are a source of hydrolytic enzymes such as chitinases, proteases, laminarinases, amylases, lipases and cellulases. For comparison, 12 halotolerant or moderately halophilic strains obtained from DSM culture collection were also evaluated for their antifungal activity against B. cinerea on tomato fruits. The most effective strains were Halomonas subglaciescola, Halobacillus litoralis, Marinococcus halophilus, Salinococcus roseus, Halovibrio variabilis and Halobacillus halophilus with a percentage of grey mould rot reduction ranging from 71% to 97%. Inoculation of mature-green tomatoes by the bacterial antagonist of Halobacillus trueperi resulted in no disease development. Our results indicate that the use of halotolerant to halophilic micro-organisms should be helpful in reducing grey mould disease of stored tomatoes.