• Research in Plant Disease
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• v.26 no.4
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• pp.210-221
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• 2020

This research was executed to select beneficial antagonists from digestive organ of Allomyrina dichotoma larva that can be put on environment friendly control against phytopathogenic fungi. We screened 38 bacterial strains inhibiting mycelial growth against eight plant pathogens through dual culture assay. The 10 strains among 38 bacterial strains were selected as beneficial microbes showing antifungal activity against Botrytis cinerea, Plasmodiophora brassicae, Colletotrichum acutatum and Phytophthora capsici through under greenhouse pot trials. The 10 bacterial strains that shown strongest antifungal activity were classified into 3 genera and 10 species, and identified as the genus Bacillus (DM146, DM152, DH2, and DH16), Paenibacillus (DF30, DH14, and DM142) and Streptomyces (DF137, DM48, and DH92) by morphological characteristics and 16s rRNA gene sequence. The 10 bacterial strains had solubilizing activity of insoluble phosphates, production of IAA (indole-3-acetic acid), β-1,3-glucanase and protease. Among the 10 bacterial strains, DM152 strain was produced significant enhancement of all growth parameters of chili pepper and tomato seedlings under greenhouse condition. Thus, this study demonstrated that gut microbes of Allomyrina dichotoma larva will be useful as a potential biocontrol agent against plant pathogens and biofertilizer.

• Journal of Microbiology and Biotechnology
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• v.33 no.2
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• pp.219-227
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• 2023

Lettuce is one of the most consumed vegetables worldwide. However, it has potential risks associated with pathogenic bacterial contamination because it is usually consumed raw. In this study, we investigated the changes in the bacterial community on lettuce (Lactuca sativa L.) in Chungcheong-do, South Korea, and the prevalence of foodborne pathogens on lettuce in different seasons using 16S rRNA gene-based sequencing. Our data revealed that the Shannon diversity index showed the same tendency in term of the number of OTUs, with the index being greatest for summer samples in comparison to other seasons. Moreover, the microbial communities were significantly different between the four seasons. The relative abundance of Actinobacteriota varied according to the season. Family Micrococcaceae was most dominant in all samples except summer, and Rhizobiaceae was predominant in the microbiome of the summer sample. At the genus level, the relative abundance of Bacillus was greatest in spring samples, whereas Pseudomonas was greatest in winter samples. Potential pathogens, such as Staphylococcus and Clostridium, were detected with low relative abundance in all lettuce samples. We also performed metagenome shotgun sequencing analysis on the selected summer and winter samples, which were expected to be contaminated with foodborne pathogens, to support 16S rRNA gene-based sequencing dataset. Moreover, we could detect seasonal biomarkers and microbial association networks of microbiota on lettuce samples. Our results suggest that seasonal characteristics of lettuce microbial communities, which include diverse potential pathogens, can be used as basic data for food safety management to predict and prevent future outbreaks.

• Food Science and Preservation
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• v.31 no.3
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• pp.474-485
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• 2024

The purposes of this study were to isolate the potential Lacticaseibacillus spp. from the feces of infants before weaning, to investigate the safety of antibiotics resistance and beta-haemolysis, and to evaluate the anti-bacterial and anti-inflammatory effects between the selected strains and Oenanthe javanica (Oj) fermented by them. As a result of analyzing the intestinal microbial community among the stools of four infants, the genus Bifidobacterium was the most dominant, but Lacticaseibacillus (L.) rhamnosus was the most frequently isolated because of the easy culture. Nine test strains, including Lactobacillus rhamnosus LGG (ATCC 53103) as the positive control, were sensitive against 8 kinds of antibiotics without vancomycin in comparison with the cut-off values at the European Food Safety Authority (EFSA), and there was no hemolysis. In the antibacterial activity experiment, the Lacticaseibacillus rhamnosus L22-FR28 (L28, KACC 92513P) strain and Oj+L28 ferment showed significantly (p<0.05) higher activities than LGG against Bacillus cereus and Staphylococcus aureus. Additionally, these decreased the activity of the NF-kB/AP-1 transcription factor and inhibited the nitric oxide and cytokines (TNF-α and IL-6) produced in macrophage RAW cells stimulated by lipopolysaccharide (LPS). Consequently, the L. rhamnosus L28 strain and Oenanthe javanica+L. rhamnosus L28 (Oj+L28) ferment selected with the high anti-inflammatory effect will improve health functionality after more research, such as the verification of animal level and identification of mechanism on an anti-inflammatory.