Abstract
To counteract global food safety hazards related to raw consumption of ready-to-eat leafy vegetables, a method to improve bacterial status using antagonistic bacteria was studied under field conditions. This is the first study to identify potential Escherichia coli antagonists from the native microbiota on leafy green vegetables and evaluate their effect in an industrial field production setting. Bacterial strains were isolated from different types of leafy green vegetables and selected upon their effect against E. coli in vitro, and out of 295 tested bacterial strains, 37 showed an antagonistic effect. Four of those antagonistic strains were coated in separate treatments onto spinach seeds and planted in the field. Both seeds and plants were analyzed by Illumina MiSeq next generation sequencing (NGS), and it was seen that the microbiota of the plants contained lower relative abundance of plant and human pathogenic genera. Higher β-diversity was observed for the samples treated with Bacillus coagulans LMG P-32205 and B. coagulans LMG P-32206 compared to control, indicating that those strains have induced substantial changes in the native microbiota of the leaves. A reduction of Escherichia-Shigella was seen for two of the isolates (Pseudomonas cedrina LMG P-32207 and Pseudomonas punonenis LMG P-32204) as the seeds developed into plants. Seeds inoculated with two of the strains (B. coagulans LMG P-32205 and B. coagulans LMG P-32206) had increased levels of Lactobacillaceae, and treatment with B. coagulans LMG P-32206 resulted in lower levels of Pantoea (from 31.4 to 12.2%). These results encourage the usage of bacterial antagonists as part of a global solution to reduce the risk of human pathogens on leafy green vegetables.
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Claims 7
Claim · model-written summary
Of 295 tested bacterial strains from leafy greens, 37 showed antagonistic effect against E. coli in vitro
- Taxon
- spinach
Spinacia oleraceat0 - Interactor
- E. coli
.jpg?width=60)
Escherichia colie1pathogen - Second interactor
- tested bacterial strainse1biocontrol_agent
- Outcome
- antagonistic effecte1
- Value
- 37e1
- Setting
- in vitroe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
t0“biocontrol of spinach”
e1“selected upon their effect against E. coli in vitro, and out of 295 tested bacterial strains, 37 showed an antagonistic effect”
Claim · model-written summary
Antagonistic strains coated on spinach seeds lowered the relative abundance of plant and human pathogenic genera in the field
- Taxon
- spinachSpinacia oleraceat0
- Treatment
- antagonistic strains were coated in separate treatments onto spinach seedse3
- Interactor
- pathogenic generae2pathogen
- Outcome
- relative abundance of plant and human pathogenic generae2
- Direction
- lowere2
- Setting
- planted in the fielde3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“biocontrol of spinach”
e2“the microbiota of the plants contained lower relative abundance of plant and human pathogenic genera”
e3“Four of those antagonistic strains were coated in separate treatments onto spinach seeds and planted in the field”
Claim · model-written summary
Bacillus coagulans treatments raised beta-diversity of the leaf microbiota compared with control
- Taxon
- spinachSpinacia oleraceat0
- Treatment
- samples treated with Bacillus coagulans LMG P-32205 and B. coagulans LMG P-32206e4
- Interactor
- Bacillus coagulans
Heyndrickxia coagulanse4biocontrol_agent - Outcome
- β-diversitye4
- Direction
- Highere4
- Comparator
- controle4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“biocontrol of spinach”
e4“Higher β-diversity was observed for the samples treated with Bacillus coagulans LMG P-32205 and B. coagulans LMG P-32206 compared to control”
Claim · model-written summary
Pseudomonas cedrina and P. punonenis reduced Escherichia-Shigella as seeds developed into plants
- Taxon
- spinachSpinacia oleraceat0
- Treatment
- Pseudomonas cedrina LMG P-32207 and Pseudomonas punonenis LMG P-32204e5
- Interactor
- Escherichia-Shigellae5other
- Second interactor
- Pseudomonas cedrina LMG P-32207Pseudomonas cedrinae5biocontrol_agent
- Outcome
- Escherichia-Shigellae5
- Direction
- reductione5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“biocontrol of spinach”
e5“A reduction of Escherichia-Shigella was seen for two of the isolates (Pseudomonas cedrina LMG P-32207 and Pseudomonas punonenis LMG P-32204)”
Claim · model-written summary
Seeds inoculated with Bacillus coagulans strains had increased Lactobacillaceae levels
- Taxon
- spinachSpinacia oleraceat0
- Treatment
- Seeds inoculated with two of the strainse6
- Interactor
- LactobacillaceaeLactobacillaceaee6other
- Second interactor
- B. coagulans LMG P-32205Heyndrickxia coagulanse6biocontrol_agent
- Outcome
- levels of Lactobacillaceaee6
- Direction
- increasede6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“biocontrol of spinach”
e6“Seeds inoculated with two of the strains (B. coagulans LMG P-32205 and B. coagulans LMG P-32206) had increased levels of Lactobacillaceae”
Claim · model-written summary
B. coagulans LMG P-32206 lowered Pantoea levels on spinach from 31.4% to 12.2%
- Taxon
- spinachSpinacia oleraceat0
- Treatment
- treatment with B. coagulans LMG P-32206e7
- Second interactor
- B. coagulans LMG P-32206Heyndrickxia coagulanse7biocontrol_agent
- Outcome
- levels of Pantoeae7
- Direction
- lowere7
- Value
- 31.4 to 12.2%e7
.jpg?width=60){kind=small}
PantoeaNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
t0“biocontrol of spinach”
e7“treatment with B. coagulans LMG P-32206 resulted in lower levels of Pantoea (from 31.4 to 12.2%)”
Claim · model-written summary
Bacterial antagonists should be used to reduce the risk of human pathogens on leafy green vegetables
Verbatim
t0“biocontrol of spinach”
e7“These results encourage the usage of bacterial antagonists as part of a global solution to reduce the risk of human pathogens on leafy green vegetables”