Inhibition of <i>Botrytis cinerea</i> and <i>Escherichia coli</i> by Lactic Acid Bacteria on Leafy Vegetables
2024
Beata Kowalska | Magdalena Szczech | Anna Lisek
The evaluation of the potentiality of lactic acid bacteria (LAB) strains isolated from fermented products to inhibit <i>Botrytis cinerea</i> and <i>Escherichia coli</i> O157:H7 growth on spinach and lettuce was conducted. From a total of forty LAB strains tested, three were selected due to their high inhibitory effect on plant pathogenic fungi. The identification of these isolates based on a 16S rRNA gene fragment sequence analysis confirmed the genus of <i>Levilactobacillus</i> sp. and <i>Lactiplantibacillus</i> sp. An effective method of coating LAB isolates on the lettuce and spinach surface was developed. The leaves were immersed in bacterial suspension (5.0 × 10<sup>6</sup> cfu mL<sup>−1</sup>) for 4 s and drained on tissue paper. LAB survived on lettuce and spinach leaves for 8 days at 6 log<sub>10</sub> cfu g<sup>−1</sup>. Additionally, these bacteria decreased the number of filamentous fungi on the leaves. These isolates were found to inhibit the growth of <i>B. cinerea</i> and <i>E. coli</i> O157:H7 in vitro conditions in growing microbiological media. Their efficacy was confirmed in vivo conditions. These isolates inhibited the development of grey mould caused by <i>B. cinerea</i> on lettuce leaves. Two LAB isolates reduced the abundance of the pathogenic bacterium <i>E. coli</i> on spinach leaves by about 0.7 log<sub>10</sub> cfu g<sup>−1</sup>. In glasshouse conditions, LAB stimulated the growth of examined plants. The lactic acid bacteria used in this study showed the capacity to be used as possible alternatives to chemical compounds in the protection of leafy vegetables against grey mould and for a decrease in <i>E. coli</i> O157:H7 contamination.
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