• Animal Bioscience
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• 제34권9호
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• pp.1479-1490
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• 2021

Objective: Our recent findings confirmed the effectiveness of sodium metabisulfite (SMB) in controlling the growth of undesirable microorganisms in fruit and vegetable discards (FVD); however, lactic acid bacteria (LAB) are susceptible to its antibacterial effects. Two series of experiments were conducted to enable the survivability of LAB during silage fermentation of a total mixed ration (TMR) containing SMB-treated FVD. Methods: In Exp. 1, the objective was to isolate a strain of LAB tolerable to the toxic effect of SMB. In Exp. 2, the SMB load was minimized through its partial replacement with a chemical mixture (CM) based on sodium benzoate (57%), potassium sorbate (29%), and sodium nitrite (14%). FVD was treated with SMB + CM (2 g each/kg biomass) and added to the TMR at varying levels (0%, 10%, or 20%), with or without KU18 inoculation. Results: The KU18 was screened as a presumptive LAB strain showing superior tolerance to SMB in broth medium, and was identified at the molecular level using 16S rRNA gene sequence analysis as Lactobacillus plantarum. Inoculation of KU18 in TMR containing SMB was not successful for the LAB development, biomass acidification, and organoleptic properties of the resultant silage. In Exp. 2, based on the effectiveness and economic considerations, an equal proportion of SMB and CM (2 g each/kg FVD) was selected as the optimal loads for the subsequent silage fermentation experiment. Slight differences were determined in LAB development, biomass acidification, and sensorial characteristics among the experimental silages, suggesting the low toxicity of the preservatives on LAB growth. Conclusion: Although KU18 strain was not able to efficiently develop in silage mass containing SMB-treated FVD, the partial substitution of SMB load with the CM effectively alleviated the toxic effect of SMB and allowed LAB development during the fermentation of SMB + CM-treated FVD in TMR.

• Journal of Microbiology and Biotechnology
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• 제29권7호
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• pp.1124-1136
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• 2019

Salinity is one of the major abiotic stresses that cause reduction of plant growth and crop productivity. It has been reported that plant growth-promoting bacteria (PGPB) could confer abiotic stress tolerance to plants. In a previous study, we screened bacterial strains capable of enhancing plant health under abiotic stresses and identified these strains based on 16s rRNA sequencing analysis. In this study, we investigated the effects of two selected strains, Bacillus aryabhattai H19-1 and B. mesonae H20-5, on responses of tomato plants against salinity stress. As a result, they alleviated decrease in plant growth and chlorophyll content; only strain H19-1 increased carotenoid content compared to that in untreated plants under salinity stress. Strains H19-1 and H20-5 significantly decreased electrolyte leakage, whereas they increased $Ca^{2+}$ content compared to that in the untreated control. Our results also indicated that H20-5-treated plants accumulated significantly higher levels of proline, abscisic acid (ABA), and antioxidant enzyme activities compared to untreated and H19-1-treated plants during salinity stress. Moreover, strain H20-5 upregulated 9-cisepoxycarotenoid dioxygenase 1 (NCED1) and abscisic acid-response element-binding proteins 1 (AREB1) genes, otherwise strain H19-1 downregulated AREB1 in tomato plants after the salinity challenge. These findings demonstrated that strains H19-1 and H20-5 induced ABA-independent and -dependent salinity tolerance, respectively, in tomato plants, therefore these strains can be used as effective bio-fertilizers for sustainable agriculture.

• The Plant Pathology Journal
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• 제35권2호
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• pp.178-187
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• 2019

Plants are exposed to biotic stresses caused by pathogen attack and complex abiotic stresses including heat and drought by dynamic climate changes. To alleviate these stresses, we investigated two bacterial stains, H26-2 and H30-3 in two cultivars ('Ryeokkwang' and 'Buram-3-ho') of Chinese cabbage in plastic pots in a greenhouse. We evaluated effects of bacterial strains on plant growth-promotion and mitigation of heat and drought stresses; the role of exopolysaccharides as one of bacterial determinants on alleviating stresses; biocontrol activity against soft rot caused by Pectobacterium carotovorum subsp. carotovorum PCC21. Strains H26-2 and H30-3 significantly increased fresh weights compared to a $MgSO_4$ solution; reduced leaf wilting and promoted recovery after re-watering under heat and drought stresses. Chinese cabbages treated with H26-2 and H30-3 increased leaf abscisic acid (ABA) content and reduced stomatal opening after stresses treatments, in addition, these strains stably colonized and maintained their populations in rhizosphere during heat and drought stresses. As well as tested bacterial cells, exopolysaccharides (EPS) of H30-3 could be one of bacterial determinants for alleviation of tested stresses in Chinese cabbages, however, the effects were different to cultivars of Chinese cabbages. In addition to bacterial activity to abiotic stresses, H30-3 could suppress incidence (%) of soft rot in 'Buram-3-ho'. The tested strains were identified as Bacillus aryabhattai H26-2 and B. siamensis H30-3 based on 16S rRNA gene sequence analysis. Taken together, H26-2 and H30-3 could be candidates for both plant growth promotion and mitigation of heat and drought stresses in Chinese cabbage.

• Journal of Microbiology and Biotechnology
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• 제31권10호
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• pp.1420-1429
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• 2021

The safety of the probiotic strain Q180, which exerts postprandial lipid-lowering effects, was bioinformatically and phenotypically evaluated. The genome of strain Q180 was completely sequenced, and single circular chromosome of 3,197,263 bp without any plasmid was generated. Phylogenetic and related analyses using16S rRNA gene and whole-genome sequences revealed that strain Q180 is a member of Lactiplantibacillus (Lp., formerly Lactobacillus) plantarum. Antimicrobial resistance (AMR) genes were bioinformatically analyzed using all Lp. plantarum genomes available in GenBank, which showed that AMR genes are present differently depending on Lp. plantarum strains. Bioinformatic analysis demonstrated that some mobile genetic elements such as prophages and insertion sequences were identified in the genome of strain Q180, but because they did not contain harmful genes such as AMR genes and virulence factor (VF)- and toxin-related genes, it was suggested that there is no transferability of harmful genes. The minimum inhibition concentrations of seven tested antibiotics suggested by the European Food Safety Authority guidelines were slightly lower than or equal to the microbiological cut-off values for Lp. plantarum. Strain Q180 did not show hemolytic and gelatinase activities and biogenic amine-producing ability. Taken together, this study demonstrated the safety of strain Q180 in terms of absence of AMR genes and VF- and toxin-related genes as a probiotic strain.

• 한국물환경학회지
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• 제36권6호
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• pp.581-591
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• 2020

In this study, two types of reactors were operated to examine the properties of methanol uptake under the high-rate denitrification process. In a sequencing batch reactor, the denitrifying activity was enriched up to 0.80 g-N/g-VSS-day for 72 days. Then, the enriched denitrifying sludge was transferred to a completely stirred tank reactor (CSTR). At the final phase on Day 46-50, the nitrogen removal efficiency was around 100% and the total nitrogen removal rate reached 0.097±0.003 kg-N/㎥-day. During the continuous process, the sludge settling index (SVI30) was stabilized as 118.3 mL/g with the biomass concentration of 1,607 mg/L. The continuous denitrifying process was accelerated by using a sequencing batch reactor (SBR) with a total nitrogen removal rate of 0.403±0.029 kg-N/㎥-day with a high biomass concentration of 8,433 mg-VSS/L. Because the reactor was open to ambient air with the dissolved oxygen range of 0.2-0.5 mg-O2/L, an increased organic carbon requirement of 5.58±0.70 COD/NO3--N was shown for the SBR in comparison to the value of 4.13±0.94 for the test of the same biomass in a completely anaerobic batch reactor. The molecular analysis based on the 16S rRNA gene showed that Methyloversatilis discipulorum and Hyphomicrobium zavarzinii were the responsible denitrifiers with the sole organic carbon source of methanol.

• 한국환경농학회지
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• 제40권1호
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• pp.67-72
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• 2021

BACKGROUND: Biological iron redox transformation alters iron minerals, which may act as effective adsorbents for arsenate [As(V)] in the environments. In the viewpoint of alleviating arsenate, microbial Fe(III) reduction was sought under high concentration of As(V). In this study, Fe(III)-reducing bacteria were isolated from the wild plant rhizosphere soils collected at abandoned mine areas, which showed tolerance to high concentration of As(V), in pursuit of potential agents for As(V) bioremediation. METHODS AND RESULTS: Bacterial isolation was performed by a series of enrichment, transfer, and dilutions. Among the isolated strains, two strains (JSAR-1 and JSAR-3) with abilities of tolerance to 10 mM As(V) and Fe(III) reduction were selected. Phylogenetic analysis using 16S rRNA genesequences indicated the closest members of Pseudomonas stutzeri DSM 5190 and Paenibacillus selenii W126, respectively for JSAR-1 and JSAR-3. Ferric and ferrous iron concentrations were measured by ferrozine assay, and arsenic concentration was analyzed by ICP-AES, suggesting inability of As(V) reduction whereas ability of Fe(III) reduction. CONCLUSION: Fe(III)-reducing bacteria isolated from the enrichments with arsenate and ferric iron were found to be resistant to a high concentration of As(III) at 10 mM. We suppose that those kinds of microorganisms may suggest good application potentials for As(V) bioremediation, since the bacteria can transform Fe while surviving under As-contaminated environments. The isolated Fe(III)-reducing bacterial strains could contribute to transformations of iron minerals which may act as effective adsorbents for arsenate, and therefore contribute to As(V) immobilization

• Journal of Microbiology and Biotechnology
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• 제31권12호
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• pp.1701-1708
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• 2021

Food safety is the most important global health issue due to foodborne pathogens after consumption of contaminated food. Foodborne bacteria such as Escherichia coli, Salmonella enterica, Staphylococcus aureus, Campylobacter spp., Bacillus cereus, Vibrio spp., Yersinia enterocolitica and Clostridium perfringens are leading causes of the majority of foodborne illnesses and deaths. These foodborne pathogens often come from the livestock feces, thus, we analyzed fecal microbial communities of three different livestock species to investigate the prevalence of foodborne pathogens in livestock feces using metagenomics analysis. Our data showed that alpha diversities of microbial communities were different according to livestock species. The microbial diversity of cattle feces was higher than that of chicken or pig feces. Moreover, microbial communities were significantly different among these three livestock species (cattle, chicken, and pig). At the genus level, Staphylococcus and Clostridium were found in all livestock feces, with chicken feces having higher relative abundances of Staphylococcus and Clostridium than cattle and pig feces. Genera Bacillus, Campylobacter, and Vibrio were detected in cattle feces. Chicken samples contained Bacillus, Listeria, and Salmonella with low relative abundance. Other genera such as Corynebacterium, Streptococcus, Neisseria, Helicobacter, Enterobacter, Klebsiella, and Pseudomonas known to be opportunistic pathogens were also detected in cattle, chicken, and pig feces. Results of this study might be useful for controlling the spread of foodborne pathogens in farm environments known to provide natural sources of these microorganisms.

• Journal of Microbiology and Biotechnology
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• 제31권12호
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• pp.1632-1642
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• 2021

Tuberculosis is a highly contagious disease caused by Mycobacterium tuberculosis. It affects about 10 million people each year and is still one of the leading causes of death worldwide. About 2 to 3 billion people (equivalent to 1 in 3 people in the world) are infected with latent tuberculosis. Moreover, as the number of multidrug-resistant, extensively drug-resistant, and totally drug-resistant strains of M. tuberculosis continues to increase, there is an urgent need to develop new anti-tuberculosis drugs that are different from existing drugs to combat antibiotic-resistant M. tuberculosis. Against this background, we aimed to develop new anti-tuberculosis drugs using probiotics. Here, we report the anti-tuberculosis effect of Pediococcus acidilactici PMC202 isolated from young radish kimchi, a traditional Korean fermented food. Under coculture conditions, PMC202 inhibited the growth of M. tuberculosis. In addition, PMC202 inhibited the growth of drug-sensitive and -resistant M. tuberculosis- infected macrophages at a concentration that did not show cytotoxicity and showed a synergistic effect with isoniazid. In a 2-week, repeated oral administration toxicity study using mice, PMC202 did not cause weight change or specific clinical symptoms. Furthermore, the results of 16S rRNA-based metagenomics analysis confirmed that dysbiosis was not induced in bronchoalveolar lavage fluid after oral administration of PMC202. The anti-tuberculosis effect of PMC202 was found to be related to the reduction of nitric oxide. Our findings indicate that PMC202 could be used as an anti-tuberculosis drug candidate with the potential to replace current chemical-based drugs. However, more extensive toxicity, mechanism of action, and animal efficacy studies with clinical trials are needed.

• Animal Bioscience
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• 제35권11호
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• pp.1689-1697
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• 2022

Objective: The aim of this study was to compare the effects of three kinds of organic acid (OA) products on the growth performance, intestinal characteristics and morphology, and cecal microflora in broilers fed a corn-soybean meal meal diet. Methods: A total of 420 one-day-old male Cobb 500 broilers with an average initial body weight of 49.11±1.02 g were used in this 42-day experiment. Birds were randomly allotted to one of five treatments (7 replicates with 12 birds per replicate). Treatments consisted of negative control (NC), basal diet; positive control (PC), basal diet+100 mg/kg of Aviramycin; OA1, basal diet+500 mg/kg of OA product 1; OA2, basal diet+1,000 mg/kg of OA product 2; and OA3, basal diet+1,200 mg/kg of OA product 3. Results: The results indicated that OA product addition had no effect on growth performance parameters, such as body weight gain, feed intake, and feed conversion ratio, from days 1 to 14, 15 to 28, and 0 to 42, or on the pH values of the intestine, intestinal weight, or intestinal weight to body weight ratio. The intestinal morphology in terms of villus height and crypt depth were affected by dietary supplementation of OA products, respectively. Furthermore, dietary addition of OAs had positive influences on the maintenance of the cecal microflora based on the results of 16S rRNA analysis. Conclusion: Dietary inclusion of three kinds of OA products all benefit broilers, but the mode of action may be different. This study provides a basis for the application of OA products used in the poultry industry.

• 대한한의학회지
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• 제42권3호
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• pp.119-138
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• 2021

Objectives: This study aimed to review the clinical research of the gut microbiome for respiratory diseases to assist the design of trials for respiratory diseases by regulating the gut microbiome with herbal medicine later. Methods: We searched three international databases (PubMed, CENTRAL and EMBASE) to investigate randomized controlled trials (RCTs) of the gut microbiome for respiratory diseases. The selected trials were analyzed by study design, subject diseases, inclusion/exclusion criteria, sample size, study period, intervention group, control group, outcome measures, and study results. Results: A total of 25 studies were included and published from 1994 to 2021 mostly in Europe and Asia. Subject diseases were many in the order of respiratory tract infection, cystic fibrosis, allergy, and so on. As outcome measures, the gut microbiome in a fecal sample was analyzed by 16S rRNA sequencing analysis method, and symptom assessment tools related each disease were used. Major intervention drugs were probiotics and the results were mostly improved in the composition and diversity of the gut microbiome. Conclusion: Clinical studies of the gut microbiome for respiratory diseases have confirmed various effects and this review provides basic data for a well-designed clinical study for respiratory diseases by regulating the gut microbiome with herbal medicine.