• Korean Journal of Microbiology
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• v.45 no.2
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• pp.133-139
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• 2009

A nutrient-concentrating system was operated to retrieve total phosphorus efficiently from a non-point pollution source. Attached bacteria were expected to play an important role in the system. Phosphorous was concentrated by formation of bacterial biofilms on rubberized coconut fiber media of the system. While concentration of total phosphorus (TP) ranged merely 0.12~0.35 mg/L in the stream water, TP levels in pore water and the media were 0.45~0.86 mg/L and 40.91~242.71 mg/kg, respectively. Total bacterial number (TBN) ranged $0.3\sim2.3\times10^6$ cells/ml in stream water, $0.4\sim4.4\times10^6$ cells/ml in pore water and $0.8\sim1.9\times10^9$ cells/g in media. There was a close correlation between TP and TBN. Based on band profiles in DGGE analyses, bacterial communities in the media were different from that in the stream water. Clostridium spp. were abundant in the stream water while Aquabacterium spp. were dominant species in early stages of biofilm formation in the media. The genera predominant in matured biofilms of the media were Clostridium and Enterococcus.

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.42-44
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• 2008

Bacterial biofilms are analogous to multi-cellular organisms or to clonal communities of higher organisms. In this respect, it can be demonstrated that biofilms display the type of genetic variation associated with macroorganisms. The formation of genetic variants from biofilms is the result of internally produced and regulated signals and the appearance of these variants coincides with dispersal from the biofilm. Moreover, the generation of such variation, has similar outcomes for the bacterial community, where diversification of phenotypic traits ensures that the bacterial community optimizes its chances of success when dispersing or surviving when challenged with environmental stress. These observations increase the complexity with which we view bacteria and also suggest that microbial systems can serve as models for the testing of eukaryotic ecological theories.

• CELLMED
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• v.2 no.3
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• pp.23.1-23.7
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• 2012

The healing properties of medicinal maggots (larval stage of Lucilia sericata) are widely used in the chirurgical debridement of non-healing wounds including diabetic foot ulcers, venous and pressure ulcers, where classical approaches have failed. Several kinds of wounds are prone to complications coming out of a specific wound bed environment. There are multi-resistant bacterial species present, their pathogenic impact is multiplied by their ability to form a biofilm. Moreover, immunological events in chronic wounds differ from those in acute wounds. Non-healing wounds are cycled in the early inflammation phase with increased levels of inflammation attributes like inflammation cytokines and matrix metalloproteinases produced by inflammation phase cells. Application of larval therapy promotes progress in the healing process to the next stages involving tissue granulation and re-epithelisation. Larval debridement is an effective method of cleaning the wound of cell debris, necrotic tissue and bacterial load. This happens in a mechanical and biological manner, but the whole complex mechanism of the maggot healing activity is still not fully elucidated. Centuries of clinical practice brings noticeable proof of the maggots' beneficial effect in wound healing management. This long history led to the investigation of the bioactive components of the larval body and its extracts in vitro. We introduce a review which describes the immunomodulation impact of maggot body components on the cellular and molecular levels of the wound healing process.

• Research in Plant Disease
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• v.23 no.3
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• pp.212-227
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• 2017

Pseudomonas chlororaphis O6, isolated from the roots of dryland, field-grown commercial wheat in the USA, enhances plant health and therefore it is used in agriculture as a biofertilizer and biocontrol agent. The metabolites produced by this pseudomonad stimulate plant growth through direct antagonism of pathogens and by inducing systemic resistance in the plant. Studies upon P. chlororaphis O6 identify the pathways through which defined bacterial metabolites generate protection against pathogenic microbes, insects, and nematodes. P. chlororaphis O6 also triggers plant resistance to drought and salinity stresses. The beneficial determinants are produced from bacterial cells as they form biofilms during root colonization. Molecular control these processes in P. chlororaphis O6 involves the global regulatory Gac/Rsm signaling cascade with cross-talk between other global regulatory pathways. The Gac/Rsm regulon allows for coordinate phasing of expression of the genes that encode these beneficial traits among a community of cells. This review provides insights on the Gac/Rsm regulon in expression of beneficial traits of the P. chlororaphis O6 which can contribute to help yield enhancement and quality in agricultural production.

• Biomolecules & Therapeutics
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• v.29 no.3
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• pp.263-267
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• 2021

Periodontal disease is primarily associated with bacterial infection such as dental plaque. Dental plaque, an oral biofilm harboring a complex microbial community, can cause various inflammatory reactions in periodontal tissue. In many cases, the local bacterial invasion and host-mediated immune responses lead to severe alveolar bone destruction. To date, plaque control, non-surgical, and surgical interventions have been the conventional periodontal treatment modalities. Although adjuvant therapies including antibiotics or supplements have accompanied these procedures, their usage has been limited by antibiotic resistance, as well as their partial effectiveness. Therefore, new strategies are needed to control local inflammation in the periodontium and host immune responses. In recent years, target molecules that modulate microbial signaling mechanisms, host inflammatory substances, and bone immune responses have received considerable attention by researchers. In this review, we introduce three approaches that suggest a way forward for the development of new treatments for periodontal disease; (1) quorum quenching using quorum sensing inhibitors, (2) inflammasome targeting, and (3) use of FDA-approved anabolic agents, including Teriparatide and sclerostin antibody.

• The Plant Pathology Journal
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• v.39 no.3
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• pp.235-244
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• 2023

Acidovorax citrulli (Ac) is a phytopathogenic bacterium that causes bacterial fruit blotch (BFB) in cucurbit crops, including watermelon. However, there are no effective methods to control this disease. YggS family pyridoxal phosphate-dependent enzyme acts as a coenzyme in all transamination reactions, but its function in Ac is poorly understood. Therefore, this study uses proteomic and phenotypic analyses to characterize the functions. The Ac strain lacking the YggS family pyridoxal phosphate-dependent enzyme, AcΔyppAc(EV), virulence was wholly eradicated in geminated seed inoculation and leaf infiltration. AcΔyppAc(EV) propagation was inhibited when exposed to L-homoserine but not pyridoxine. Wild-type and mutant growth were comparable in the liquid media but not in the solid media in the minimal condition. The comparative proteomic analysis revealed that YppAc is primarily involved in cell motility and wall/membrane/envelop biogenesis. In addition, AcΔyppAc(EV) reduced biofilm formation and twitching halo production, indicating that YppAc is involved in various cellular mechanisms and possesses pleiotropic effects. Therefore, this identified protein is a potential target for developing an efficient anti-virulence reagent to control BFB.

• Journal of Microbiology
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• v.45 no.2
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• pp.113-121
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• 2007

The bacterial diversity inherent to the biofilm community structure of a modified rotating biological contactor wastewater treatment process, referred to as the Rotating Activated Bacillus Contactor (RABC) process, was characterized in this study, via both culture-dependent and culture-independent methods. On the basis of culture-dependent methods, Bacillus sp. were found to exist in large numbers on the biofilm (6.5% of the heterotrophic bacteria) and the microbial composition of the biofilms was quite simple. Only three phyla were identified-namely, the Proteobacteria, the Actinobacteria (High G+C Gram-positive bacteria), and the Firmicutes (Low G+C Gram-positive bacteria). The culture-independent partial 16S rDNA sequence analysis revealed a considerably more diverse microbial composition within the biofilms. A total of eight phyla were recovered in this case, three of which were major groups: the Firmicutes (43.9%), the Proteobacteria (28.6%), and the Bacteroidetes (17.6%). The remaining five phyla were minor groups: the Planctomycetes (4.4%), the Chlorobi (2.2%), the Actinobacteria (1.1%), the Nitrospirae (1.1%), and the Verrucomicrobia (1.1%). The two most abundant genera detected were the endospore-forming bacteria (31.8%), Clostridium and Bacillus, both of which are members of the Firmicutes phylum. This finding indicates that these endospore-forming bacteria successfully colonized and dominated the RABC process biofilms. Many of the colonies or clones recovered from the biofilms evidenced significantly high homology in the 16S rDNA sequences of bacteria stored in databases associated with advanced wastewater treatment capabilities, including nitrification and denitrification, phosphorus accumulation, the removal of volatile odors, and the removal of chlorohydrocarbons or heavy metals. The microbial community structures observed in the biofilms were found to correlate nicely with the enhanced performance of advanced wastewater treatment protocols.

• The Plant Pathology Journal
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• v.25 no.1
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• pp.62-69
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• 2009

In this study, we characterized the bacterial strain KJ2C12 in relation with its biocontrol activity against Phytophthora capsici on pepper, and identified this strain using morphological, physiological, biochemical, fatty acid methyl ester, and 16S rRNA gene sequence analyses. Strain KJ2C12 significantly (P=0.05) reduced both final disease severity and areas under the disease progress curves of 5-week-old pepper plants inoculated with P. capsici compared to buffer-treated controls. As for the production of antibiotics, biofilms, biosurfactant, extracellular enzyme, HCN, and swarming activity, strain KJ2C12 produced an extracellular enzyme with protease activity, but no other productions or swarming activity. However, Escherichia coli produced weak biofilm only. Strain KJ2C12 could colonize pepper roots more effectively in a gnotobiotic system using sterile quartz sand compared to E. coli over 4 weeks after treatments. However, no bacterial populations were detected in 10 mM $MgSO_4$ buffer-treated controls. Strain KJ2C12 produced significantly higher microbial activity than the $MgSO_4$-treated control or E. coli over 4 weeks after treatments. Bacterial strain KJ2C12 was identified as Bacillus luciferensis based on morphological, physiological, and biochemical characteristics as well as FAME and 16S rRNA gene sequence analyses. In addition, these results suggested that B. luciferensis strain KJ2C12 could reduce Phytophthora blight of pepper by protecting infection courts through enhanced effective root colonization with protease production and an increase of soil microbial activity.

• The Journal of the Korean dental association
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• v.55 no.8
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• pp.556-564
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• 2017

Endodontic surgery is a procedure to treat apical periodontitis or abscess in cases that did not heal after nonsurgical treatment or retreatment. This might include situations with persistent intracanal infection after root canal treatment. Other reasons might be found in extraradicular infection, such as bacterial biofilm on the apical root surface or bacteria within the lesion. For many years, the treatment standard was the traditional approach with surgical burs and amalgam for root-end filling. Endodontic microsurgery is the most recent step in the evolution of endodontic surgery, applying not only ultrasonic tip and biocompatible filling materials but also incorporating high-power magnification and illumination. Although many studies have been published that advocate the use of modern technique, the traditional techniques are still widely used in the surgery community. The purpose of this study was to demonstrate the endodontic microsurgery procedure including the root-end preparation and filling with the use of a surgical operating microscope.

• Journal of Microbiology
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• v.37 no.4
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• pp.263-266
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• 1999

In examining bacterial growth on glass surfaces immersed in sea water, we found serious differences between enumeration methods. Therefore, we compared various methods and found sonication and direct count methods were superior to other methods. Since the direct count method was not suitable for long-term investigation, we chose the sonication method and confirmed that sonication periods 8 times for 30 seconds was optimal for the detachment of bacteria from glass surfaces.