• The Plant Pathology Journal
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• v.40 no.5
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• pp.498-511
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• 2024

Bacterial wilt caused by Ralstonia solanacearum is a destructive disease that affects potato production, leading to severe yield losses. Currently, little is known about the changes in the assembly and functional adaptation of potato rhizosphere microbial communities during different stages of R. solanacearum infection. In this study, using amplicon and metagenomic sequencing approaches, we analyzed the changes in the composition and functions of bacterial and fungal communities in the potato rhizosphere across four stages of R. solanacearum infection. The results showed that R. solanacearum infection led to significant changes in the composition and functions of bacterial and fungal communities in the potato rhizosphere, with various microbial properties (including α,β-diversity, species composition, and community ecological functions) all being driven by R. solanacearum infection. The relative abundance of some beneficial microorganisms in the potato rhizosphere, including Firmicutes, Bacillus, Pseudomonas, and Mortierella, decreased as the duration of infection increased. Moreover, the related microbial communities played a significant role in basic metabolism and signal transduction; however, the functions involved in soil C, N, and P transformation weakened. This study provides new insights into the dynamic changes in the composition and functions of potato rhizosphere microbial communities at different stages of R. solanacearum infection to adapt to the growth promotion or disease suppression strategies of host plants, which may provide guidance for formulating future strategies to regulate microbial communities for the integrated control of soil-borne plant diseases.

• Animal Bioscience
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• v.37 no.5
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• pp.883-895
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• 2024

Objective: This study aimed to investigate the effects of dietary supplementation of a fatty acid-balanced oil, instead of soybean oil, on reproductive performance, nutrient digestibility, blood indexes, milk composition in lactating sows, and fecal microbial composition in piglets. Methods: Twenty-four sows (Landrace×Yorkshire, mean parity 4.96) were randomly allotted to two treatments with twelve pens per treatment and one sow per pen based on their backfat thickness and parity. The experiment began on day 107 of gestation and continued until weaning on day 21 of lactation, lasting for 28 days. The control group (CG) was fed a basal diet supplemented with 2% soybean oil and the experimental group (EG) was fed the basal diet supplemented with 2% fatty acid-balanced oil. Results: The fatty acid-balanced oil supplementation increased (p<0.05) the apparent total tract digestibility of dry matter, crude protein, and gross energy in sows. The lower (p<0.05) serum high-density lipoprotein cholesterol and albumin levels of sows were observed in the EG on day 21 of lactation. Dietary supplementation with the fatty acid-balanced oil decreased the fat content, increased the immunoglobulin G level, and changed (p<0.05) some fatty acid content in milk. Moreover, the fatty acid-balanced oil supplementation changed (p<0.05) the fecal microbial composition of piglets, where the average relative abundance of Spirochaetota was decreased (p<0.05) by 0.55% at the phylum level, and the average relative abundance of some potentially pathogenic fecal microorganism was decreased (p<0.05) at the species level. Conclusion: The fatty acid-balanced oil improved nutrient digestibility, changed the serum biochemical indices and milk composition of sows, and ameliorated the fecal microbial composition of piglets.

• Journal of Ginseng Research
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• v.39 no.4
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• pp.392-397
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• 2015

Background: Red ginseng (RG) is processed from Panax ginseng via several methods including heat treatment, mild acid hydrolysis, and microbial conversion to transform the major ginsenosides into minor ginsenosides, which have greater pharmaceutical activities. During the fermentation process using microbial strains in a machine for making red ginseng, a change of composition occurs after heating. Therefore, we confirmed that fermentation had occurred using only microbial strains and evaluated the changes in the ginsenosides and their chemical composition. Methods: To confirm the fermentation by microbial strains, the fermented red ginseng was made with microbial strains (w-FRG) or without microbial strains (n-FRG), and the fermentation process was performed to tertiary fermentation. The changes in the ginsenoside composition of the self-manufactured FRG using the machine were evaluated using HPLC, and the 20 ginsenosides were analyzed. Additionally, we investigated changes of the reducing sugar and polyphenol contents during fermentation process. Results: In the fermentation process, ginsenosides Re, Rg1, and Rb1 decreased but ginsenosides Rh1, F2, Rg3, and Compound Y (C.Y) increased in primary FRG more than in the raw ginseng and RG. The content of phenolic compounds was high in FRG and the highest in the tertiary w-FRG. Moreover, the reducing sugar content was approximately three times higher in the tertiary w-FRG than in the other n-FRG. Conclusion: As the results indicate, we confirmed the changes in the ginsenoside content and the role of microbial strains in the fermentation process.

• The Plant Pathology Journal
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• v.38 no.6
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• pp.692-699
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• 2022

Bacterial wilt caused by Ralstonia solanacearum is considered one of the most harmful diseases of pepper plants. Recently, research on plant disease control through the rhizosphere microbiome has been actively conducted. In this study, the relationship with disease occurrence between the neighboring plant confirmed by analyzing the physicochemical properties of the rhizosphere soil and changes in the microbial community. The results confirmed that the microbial community changes significantly depending on the organic matters, P₂O₅, and clay in the soil. Despite significant differences in microbial communities according to soil composition, Actinobacteriota at the phylum level was higher in healthy plant rhizosphere (mean of relative abundance, D: 8.05 ± 1.13; H: 10.06 ± 1.59). These results suggest that Actinobacteriota may be associated with bacterial wilt disease. In this study, we present basic information for constructing of healthy soil in the future by presenting the major microbial groups that can suppress bacterial wilt.

• Journal of Environmental Science International
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• v.30 no.8
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• pp.703-708
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• 2021

To improve the environmental management and resources, in this study, we aimed to investigate the effect of adding oyster shell powder to Hanwoo manure on its characteristics and microbial composition during the storage period. Additives were deposited on top of the manure surface at the rate of 0, 0.5, and 1% of oyster shell powder per 200 g of Hanwoo manure in a plastic container with three replicates; however, untreated manure litter served as the control. Manure characteristics (dry matter, organic matter and crude ash) and microbial composition (lactic acid bacteria, yeast, Bacillus subtilis, Salmonella, and E.coli) were evaluated at day 0, 2, 4, and 8. Manure characteristics exhibited an effect on dry matter, organic matter, and crude ash at day 2 and 8 (p<0.05), and not for day 0 and 4 (p>0.05). With the exception of yeast content at day 4 of storage, lactic acid bacteria, yeast, Bacillus subtilis, Salmonella, and E.coli exhibited no significant differences in all conditions during the storage period. Conclusively, addition of 1% oyster shell powder to Hanwoo manure resulted in slightly better manure characteristics; however, its microbial composition remained unchanged.

• Journal of Microbiology and Biotechnology
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• v.34 no.4
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• pp.757-764
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• 2024

Despite considerable advancements achieved using next-generation sequencing technologies in exploring microbial diversity, several species of the gut microbiome remain unknown. In this transformative era, culturomics has risen to prominence as a pivotal approach in unveiling realms of microbial diversity that were previously deemed inaccessible. Utilizing innovative strategies to optimize growth and culture medium composition, scientists have successfully cultured hard-tocultivate microbes. This progress has fostered the discovery and understanding of elusive microbial entities, highlighting their essential role in human health and disease paradigms. In this review, we emphasize the importance of culturomics research on the gut microbiome and provide new theories and insights for expanding microbial diversity via the optimization of cultivation conditions.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.4
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• pp.239-246
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• 2003

We examined the relationships among community composition, microbial population, and microbial biomass to determine whether different land use leads to differences in microbial community composition. And also the relationships between soil characteristics and microbial community composition were investigated. There was no difference in pH between uncultivated and cultivated soils, but electrical conductivity, and contents of organic matter, available P and exchangeable cations were greater in the cultivated soil compared to the uncultivated soil. A linear correlation ($r^2=0.557$, n=18, p<0.01) was found between biomass-C estimated with fumigation extraction technique and total amount of fatty acids. An increase of fatty acid methyl esters (FAMEs) for bacteria, actinomycetes, fungi and protozoa was observed in cultivated soil.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1593-1604
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• 2016

Recently, bacterial quorum quenching (QQ) has been proven to have potential as an innovative approach for biofouling control in membrane bioreactors (MBRs) for advanced wastewater treatment. Although information regarding the microbial community is crucial for the development of QQ strategies, little information exists on the microbial ecology in QQ-MBRs. In this study, the microbial communities of biofilm were investigated in relation to the effect of QQ on anoxic/oxic MBRs. Two laboratory-scale MBRs were operated with and without QQ-beads (QQ-bacteria entrapped in beads). The transmembrane pressure increase in the QQ-MBRs was delayed by approximately 100-110% compared with conventional- and vacant-MBRs (beads without QQ-bacteria) at 45 kPa. In terms of the microbial community, QQ gradually favored the development of a diverse and even community. QQ had an effect on both the bacterial composition and change rate of the bacterial composition. Proteobacteria and Bacteroidetes were the most dominant phyla in the biofilm, and the average relative composition of Proteobacteria was low in the QQ-MBR. Thiothrix sp. was the dominant bacterium in the biofilm. The relative composition of Thiothrix sp. was low in the QQ-MBR. These findings provide useful information that can inform the development of a new QQ strategy.

• Journal of Applied Biological Chemistry
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• v.65 no.1
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• pp.63-74
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• 2022

Microbial dysbiosis in the gut is associated with human diseases, and variations in mucus alter gut microbiota. Therefore, we explored the effects of mucin on the gut microbiota using a community of 19 synthetic gut microbial species. Cultivation of these species in modified Gifu anaerobic medium (GAM) supplemented with mucin before synthetic community assembly facilitated substantial growth of the Bacteroides, Akkermansia, and Clostridium genera. The results of 16S rRNA microbial relative abundance profiling revealed more of the beneficial microbes Collinsella, Bifidobacterium, Ruminococcus, and Lactobacillus. This increased acetate levels in the community cultivated with, rather than without (control), mucin. We identified differences in predicted cell function and metabolism between microbes cultivated in GAM with and without mucin. Mucin not only changed the composition of the gut microbial community, but also modulated metabolic functions, indicating that it could help to modulate microbial changes associated with human diseases.

• Journal of Applied Biological Chemistry
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• v.58 no.3
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• pp.209-218
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• 2015

Fructooligosaccharides have been mainly produced by microbial fructosyltransferases (FTase) enzymes. The present work focuses on the optimization of medium composition and cultivation parameters affecting FTase produced by Penicillium aurantiogriseum AUMC 5605 in shake flask cultivation. FTase production was optimized in two steps using DeMeo's fractional factorial design. A 1.46-fold increase in FTase production (105.4 U/mL) was achieved using the optimized culture medium consisting of (g/L): sucrose, 600; yeast extract, 10; $K_2HPO_4$, 5; $MgSO_4{\cdot}7H_2O$, 0.5; $(NH_4)_2SO_4$, 1.0 and KCl, 0.5. The obtained results showed that the maximum FTase enzyme activity was produced at initial cultivation pH values ranging from 6.0-6.5, at agitation speed of 200 rpm and using vegetative fungal cells as inoculum. Moreover, results showed that optimization of medium composition and some cultivation parameters resulted in an increase of about 93.7% in the enzyme activity than the nonoptimized cultivation conditions after 96 h of cultivation. Additionally, maximum production and specific production rates recorded 2340 U/L/h and 102 U/L/h/g cells, respectively.