• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.77-86
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• 2018

The human pathogen and food spoiler Bacillus cereus can form biofilms that act as a persistent source of contamination, which is of public health concern. This study aimed to understand how the source of isolation might affect the behavior of biofilm formation. Biofilm formation abilities of 56 strains of B. cereus isolated from different environments, including human food poisoning, farm, and food, were determined. Crystal violet assay results revealed significant (p < 0.05) differences in biofilm formation abilities among the strains isolated from different sources only at an early stage of incubation. However, strain origin showed no impact on later stage of biofilm formation. Next, correlation of the group of isolates on the basis of their biofilm-forming abilities with the number of sessile cells, sporulation, and extracellular polymeric substance (EPS) formation was determined. The number of sessile cells and spores in biofilms was greatly influenced by the groups of isolates that formed dense, moderate, and weak biofilms. The contribution of extracellular DNA and/or proteins to EPS formation was also positively correlated with biofilm formation abilities. Our results that the source of isolation had significant impact on biofilm formation might provide important information to develop strategies to control B. cereus biofilm formation.

• Journal of the Korean Wood Science and Technology
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• v.46 no.6
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• pp.692-702
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• 2018

Streptococcus mutans causes oral diseases, including tooth decay, by producing a biofilm called plaque. Therefore, inhibition of biofilm formation is essential for maintaining oral health. Plants produce a variety of secondary metabolites, which act as starting sources for the discovery of new bioactive chemicals that inhibit biofilm formation of S. mutans. Previous studies have reported on chemicals with antibiotic activity for the inhibition of biofilm formation by S. mutans. In this study, nine plant extracts from Melonis Pedicellus, Agastachis Herba, Mori Cortex Radicis, Diospyros kaki leaves, Agrimoniae Herba, Polygoni Multiflori Radix, Lycopi Herba, Elsholtziae Herba, and Schizonepetae Spica were screened for the inhibition of biofilm formation from a plant extract library. The water-soluble compounds of the extracts did not affect cell growth but selectively inhibited biofilm formation. These results suggest that the selected plant extracts constitute novel biofilm formation inhibitors, with a novel biological mechanism, for improving oral hygiene.

• Food Science of Animal Resources
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• v.41 no.2
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• pp.288-299
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• 2021

Biofilm formation of Geobacillus thermodenitrificans, Geobacillus thermoglucosidans and Anoxybacillus flavithermus in milk on stainless steel were monitored at 55℃, 60℃, and 65℃ for various incubation times. Although species of Geobacillus showed a rapid response and produced biofilm within 4 h on stainless steel, a delay (lag time) was observed for Anoxybacillus. A hyperbolic equation and a hyperbolic equation with lag could be used to describe the biofilm formation of Geobacillus and Anoxybacillus, respectively. The highest biofilm formation amount was obtained at 60℃ for both Geobacillus and Anoxybacillus. However, the biofilm formation rates indicated that the lowest rates of formation were obtained at 60℃ for Geobacillus. Moreover, biofilm formation rates of G. thermodenitrificans (1.2-1.6 Log10CFU/mL∙h) were higher than G. thermoglucosidans (0.4-0.7 Log10CFU/mL∙h). Although A. flavithermus had the highest formation rate values (2.7-3.6 Log10CFU/mL∙h), this was attained after the lag period (4 or 5 h). This study revealed that modeling could be used to describe the biofilm formation of thermophilic bacilli in milk.

• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1871-1879
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• 2015

The complex roles of flagella in the pathogenesis of Campylobacter jejuni, a major cause of worldwide foodborne diarrheal disease, are important. Compared with the wild-type, an insertional mutation of the flgA gene (cj0769c) demonstrated significant decrease in the biofilm formation of C. jejuni NCTC11168 on major food contact surfaces, such as polystyrene, stainless steel, and borosilicate glass. The flgA mutant was completely devoid of flagella and non-motile whereas the wild-type displayed the full-length flagella and motility. In addition, the biofilm formation of the wild-type was inversely dependent on the viscosity of the media. These results support that flagellar-mediated motility plays a significant role in the biofilm formation of C. jejuni NCTC11168. Moreover, our adhesion assay suggests that it plays an important role during biofilm maturation after initial attachment. Furthermore, C. jejuni NCTC11168 wild-type formed biofilm with a net-like structure of extracellular fiber-like material, but such a structure was significantly reduced in the biofilm of the flgA mutant. It supports that the extracellular fiber-like material may play a significant role in the biofilm formation of C. jejuni. This study demonstrated that flgA is essential for flagellar biosynthesis and motility, and plays a significant role in the biofilm formation of C. jejuni NCTC11168.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.5
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• pp.456-460
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• 2009

Biofilm is a structured community of microorganism encapsulated within a self-developed polymeric matrix and adherent to a living or a solid surface. In this study, we investigated the effects of various substrates on the formation of biofilm in Vibrio parahaemolyticus. We found that biofilm formation profoundly increased in a substrate, that consisted of calcium chloride, calcium nitrate, and calcium sulfate in 1% peptone water. On the other hand, a dramatic reduction in biofilm formation was observed in a substrate, that consisted of glucose and ferric chloride in LB broth. These results suggest that V. parahaemolyticus prefer to form a biofilm on the surface of a crustacean or a clam, where calcium ion is rich, and also where seawater temperature is relatively lower. In contrast, high levels of glucose in a crustacean or a clam body resulting from increased seawater temperature, can make V. parahaemolyticus detach from it and lead to free floating.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.178-188
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• 2019

Licorice, which has an extensive history of use as an herbal medicine, has been suggested to have oral health benefits. However, to date, no systematic study has been conducted on the preparation method of licorice extracts for oral health. In this study, licorice extracts prepared using water and ethanol were investigated for its ability to inhibit the biofilm formation of Streptococcus mutans. The licorice extract prepared with around 60% ethanol effectively inhibited the biofilm formation of S. mutans. Licorice extracted with 50% ethanol almost completely inhibited the biofilm formation at 1.5 g/L of licorice extract. This inhibitory activity was confirmed in a microplate assay and a flow cell system. Glycyrrhetic acid was extracted from licorice effectively with 60% ethanol concentration. The strong inhibitory activity of glycyrrhetic acid and the synergistic inhibition with glycyrrhizin on biofilm formation were suggested as major reasons for a concentration-specific extraction. These results suggest that licorice extract prepared using around 60% ethanol effectively inhibits the biofilm formation of S. mutans.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.2071-2078
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• 2018

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight, which results in severe economic damage to rice farms. Xoo produces biofilms for pathogenesis and survival both inside and outside the host. Biofilms, which are important virulence factors, play a key role in causing the symptoms of Xoo infection. In the present study, we investigated the nutritional conditions for biofilm formation by Xoo. Although Xoo biofilm formation may be initiated by interactions with the host, Xoo biofilm cannot mature without the support of favorable nutritional conditions. Nitrogen sources inhibited Xoo biofilm formation by overwhelming the positive effect that cell growth has on it. However, limited nutrients with low amino acid concentration supported biofilm formation by Xoo in the xylem sap rather than in the phloem sap of rice.

• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.135-139
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• 2006

Most bacteria form biofilm as self-defence system, making efficient food sanitization, preservation, and instrument washing more difficult. Biofilm formation of Salmonella, E. coli, B. cereus, and S. aureus was observed during 24 hr food preservations by performing microtiter plate and glass wool assays. Most cells formed biofilm and attached onto glass wool. When biofilm formation and injury were analyzed on the microtiter plate, 10 and 20% acid-injured E. coli and S. aureus, respectively, 30-50% cold temperature $(4^{\circ}C)-injured$ B. cereus and E. coli, and 30-55% 6% sodium chloride solution-injured Salmonella showed significant biofilm formation. Results indicate biofilm formation level differed within species depending on type of stress.

• International Journal of Oral Biology
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• v.35 no.4
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• pp.203-207
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• 2010

A number of bacterial species coexist in oral cavities as a biofilm rather than a planktonic arrangement. By forming an oral biofilm with quorum sensing properties, microorganisms can develop a higher pathogenic potential and stronger resistance to the host immune system and antibiotics. Hence, the inhibition of biofilm formation has become a major research issue for the future prevention and treatment of oral diseases. In this study, we investigated the effects of pentose on biofilm formation and phenotypic changes using wild type oral bacteria obtained from healthy human saliva. D-ribose and D-arabinose were found to inhibit biofilm formation, but have no effects on the growth of each oral bacterium tested. Pentoses may thus be good candidate biofilm inhibitors without growth-inhibition activity and be employed for the future prevention or treatment of oral diseases.

• Korean Journal of Microbiology
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• v.50 no.2
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• pp.108-113
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• 2014

Pseudomonas aeruginosa and Vibrio vulnificus are Gram-negative human pathogens, which exert their virulence through quorum sensing (QS) regulation. The infection of these pathogens have been known to be mediated by biofilm formation in many cases and this study carried out the time-course analysis of biofilm formation depending on the QS regulation in P. aeruginosa and V. vulnificus. In P. aeruginosa, our results demonstrated that QS-deficient mutant better attached to surface at initial stage of biofilm formation, but poorly proceeded to the maturation of the biofilm structure, while wild type less attached at initial stage but developed highly structured biofilm at late stage. Because of this, the quantitative comparison of biofilm formation between wild type and the QS mutant showed the reversion; the QS mutant formed more biofilm until 10 h after inoculation than wild type, but wild type formed much more biofilm after 10 h than QS mutant. V. vulnificus has been reported to form more biofilm with the mutation on QS system. When we performed the same time-course analysis of the V. vulnificus biofilm formation, the reversion was not detected even with prolonged culture for 108 h and the QS mutant always forms more biofilm than wild type. These results indicate that the QS regulation negatively affects the attachment at early stage but positively facilitates the biofilm maturation at late stage in P. aeruginosa, while the QS regulation has a negative effect on the biofilm formation throughout the biofilm development in V. vulnificus. Based on our results, we suggest that the developmental stage of biofilm and bacterial species should be considered when the QS system is targeted for biofilm control.