- Original Article
In vitro antibiofilm activity of the melanin from Auricularia auricula, an edible jelly mushroom
Annals of Microbiology volume 62, pages 1523–1530 (2012)
A melanin derived from Auricularia auricula was characterized based on ultraviolet-visible (UV), infrared (IR), electron paramagnetic resonance (EPR) spectra and chemical tests. The antibiofilm activity of the isolated A. auricula melanin against Escherichia coli K-12, Pseudomonas aeruginosa PAO1 and P. fluorescens P-3 was examined using crystal violet and LIVE/DEAD BacLight staining as well as confocal laser scanning microscopy (CLSM). The results showed that A. auricula melanin could inhibit significantly biofilm formation of E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3, while no inhibitory effects on growth were found. CLSM analysis showed that A. auricula melanin treatment resulted in thinner and looser biofilm compared with the control. The current study reveals for the first time the antibiofilm activity of melanin derived from A. auricula.
Biofilms are film-like structures formed by aggregates of bacterial cells on biotic and abiotic surfaces. These naturally existing biofilms are major threat to human beings (Wang et al. 2007), with 80% of bacterial infections being caused by biofilms (Rasmussen and Givskov 2006). Bacteria occurring in biofilms are between 10- and 1,000-fold more resistant to antibiotics, leading to serious clinical problems, particularly regarding avoidance of host immune systems (Brooun et al. 2000). Biofilms are a major cause of nosocomial infections. They cause persistent infections by forming biofilms on the surface of in vivo medical devices such as contact lens, artificial joints, and synthetic valves (Wang et al. 2007). Bacterial attachment to surfaces and subsequent biofilm formation are important steps in the establishment of chronic infections and persistence in host tissues (Costerton et al. 1999). Biofilms can delay wound healing significantly (Percival and Cutting 2009). In the food industry, biofilms can be a source of recalcitrant contaminations, causing food spoilage, and are possible sources of public health problems such as outbreaks of food-borne pathogens. Biofilms are difficult to eradicate due to their resistant phenotype (Camilli and Bassler 2006; Domka et al. 2007). However, the mechanisms by which bacteria growing in biofilms attain this resistance are still unknown. Moreover, the resistance to antimicrobial agents of biofilm-embedded bacteria make it important to search for novel agents that can effectively kill these bacteria. Novel strategies are therefore required to deal with biofilm-mediated infections.
Auricularia auricula, commonly known as ‘tree-ear’, is a species of edible mushroom found worldwide. From ancient times, the mushroom has been used widely in Chinese cuisine, and is known for its pharmaceutical effects in folk medicine. Auricularia auricula has been reported to have many biological activities, including antitumor (Misaki et al. 1981; Mizuno et al. 1995), hypocholesterolemia (Cheung 1996), hypoglycemic (Takeujchi et al. 2004), antioxidant (Finkel and Holbrook 2000; Acharya et al. 2004) and anticoagulant (Yoon et al. 2003) activity. These potent medicinal functions are mediated mostly by non-starch polysaccharide components, especially beta-glucans (Zhang et al. 1995). Nowadays, there is considerable interest in the exploitation of this fungus. Most recently, Zhu et al. (2011) reported that the extracted pigments could effectively inhibit the production of violacein, a quorum-sensing (QS)-regulated behavior in Chromobacterium violaceum CV026.
Here, the pigment from A. auricula fruiting bodies was characterized, and the ability of this pigment to inhibit biofilm formation of Escherichia coli K-12, Pseudomonas aeruginosa PAO1 and P. fluorescens P-3 was investigated by monitoring biofilms using confocal laser scanning microscopy (CLSM).
Materials and methods
Bacterial strains and growth conditions
Pseudomonas aeruginosa PAO1 and P. fluorescens P-3 were procured from Fisheries Research Institute, Shanghai, China. Escherichia coli K-12 was supplied by Nanjing Center for Disease Control and Prevention, Jiangsu province, China. The three bacteria were used to determine biofilm formation and were cultured routinely in Luria-Bertani (LB) broth (0.5% yeast extract, 1% tryptone, 0.5% NaCl) at 37°C for the exponential growth phase experiments.
Extraction and purification of A. auricula pigment
The fruiting bodies of A. auricula produced in Liaoning province, China were purchased from a local supermarket. Taxonomic identification of fruiting bodies was confirmed by a senior mycologist (Xin Zhentao, Institutes of Edible Mushroom, Shanghai Academy of Agricultural Sciences), based on its clearly ear-like shaped fruit bodies and its cylindrical basidia with three transverse septa (internal cross-walls dividing the hyphae). Analysis of internal transcribed spacer (ITS) regions was used to determine species identification of fruiting bodies of A. auricula. After milling of dried fruiting bodies to a fine powder, 10 g dried powder was extracted using 300 ml 3 M HCl for 1 h at 60°C. The melanin precipitates were recovered by centrifugation at 5,000 rpm for 20 min and sonicated with 300 ml 1.5 M NaOH for 1 h. The supernatant was acidified with 2 M HCl to pH 2, then incubated for 12 h at 80°C. The precipitate obtained was purified by acid hydrolysis using 6 M HCl at 100°C for 2 h to remove carbohydrates and proteins, and treated with chloroform to wash away lipids. The precipitate was then dried at 30°C, re-dissolved in 2 M NaOH and centrifuged at 5,000 rpm for 20 min. The supernatant was precipitated by the addition of 2 M HCl, washed with distilled water and lyophilized, and then stored at −20°C for further experiments (Selvakumar et al. 2008).
Characterization of A. auricula pigment
The physical and chemical characteristics of A. auricula pigment were measured according to standard procedures (Paim et al. 1990), including solubility in water and common organic solvents (ethanol, hexane, acetone, benzene and chloroform), oxidized bleaching by KMnO4, K2Cr2O7, NaOCl and H2O2, and reaction with FeSO4. The melanin obtained from A. auricula was dissolved in 3 ml borate buffer (pH 8) and its ultraviolet-visible (UV) absorption spectrum was recorded by a U-1800 HITACHI spectrophotometer (Hitachi, Japan) (Ravishankar et al. 1995). The infrared (IR) spectrum was recorded with a Thermo IR 200 Fourier transform infrared spectrometer (Thermo, Barrington, IL) in the frequency range 4,000–500 cm−1. KBr samples were obtained from a uniformly prepared mixture contained 2 mg A. auricula pigment sample and 150 mg spectrometric grade KBr (Ellis and Griffiths 1974; Ravishankar et al. 1995). The electron paramagnetic resonance (EPR) spectrum of the pigment was taken in a Bruker EMX- 10/12 EPR Spectrophotometer (Bruker, Germany).
Determination of minimal inhibitory concentration
Minimal inhibitory concentration (MIC) was determined by a microtiter broth dilution method as recommended by the Clinical and Laboratory Standards Institute (Khan et al. 2009). The MIC was defined as the lowest antibiotic concentration that yielded no visible growth. Cell suspensions (100 μl) were inoculated into the wells of 96-well microtitre plates in the presence of A. auricula pigment with different final concentrations. The inoculated microplates were incubated at 37°C for 24 h before being read.
Biofilm formation inhibition assay
The quantification of biofilm formation using minimal biofilm eradication concentration assay system devices (MBEC, Innovotech, Edmonton, Canada) was performed according to the manufacturer’s instructions and as described previously (Girennavar et al. 2008). The MBEC device is similar to a 96-well plate. The lid of the MBEC device contains 96 pegs on which biofilms formed. The planktonic cells were growing in the 96 wells. Overnight cultures were inoculated (1: 100) in LB media for E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3. Aliquots of these diluted cultures were added to a 96-well plate. To assess the impact of A. auricula pigment on biofilm formation, A. auricula pigment was dissolved in appropriate concentrations of dimethylsulfoxide (DMSO), sterilized by filtration through a 0.22 μm membrane filter and added to these culture suspensions. Auricularia auricula melanin was omitted in the control. The lid of the MBEC device (containing the pegs on which biofilms formed) was inserted into the plate. The plate was incubated at 37°C for 24 h without shaking. After incubation, suspension cultures in wells were spread on LB plates to confirm any antibacterial activity of the samples, and the peg lid was washed three times with sterile distilled water. The biofilms on the peg lid were stained with 125 μl 0.3% crystal violet per well for 20 min. The excess dye was removed by washing the peg lid three times with sterile distilled water. Dye associated with the attached biofilm was dissolved with 200 μl 95% ethanol. Aliquots of the solubilized dye from each well (125 μl) were transferred to a separated well in an optically clear flat-bottom 96-well plate and the optical density (OD) was measured at 590 nm. Each data point was averaged from eight replicate wells and the standard deviation (SD) was calculated.
Confocal laser scanning microscopy
The biofilms were monitored under a CLSM (Leica TCS SP2; Leica Microsystems, Heidelberg, Germany) as described previously (Berney et al. 2007; Rasmussen et al. 2005). Overnight cultures of strains incubated in LB medium were diluted to a final density of 1.0 × 106 CFU ml−1 with fresh medium. CLSM was performed on biofilms formed on plastic coverslips (0.2 mm thick and 13 mm in diameter; Nunc, Roskilde, Denmark) by dispensing 1 ml cell suspensions into the wells of 24-well microtitre plates. Plates were incubated statically at 37°C for 48 h. The biofilms were exposed to the A. auricula pigment (80 μg ml−1) for a further 24 h. Coverslips with cells grown in the medium with DMSO (1%) were employed as control. At the end of incubation, the coverslips were gently washed with sterile distilled water and stained with the LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Carlsbad, CA) according to the manufacturer’s introductions. Stained coverslips were washed gently twice with sterile distilled water and observed with CLSM. The Leica confocal software was used for analysis of biofilm images, which allowed for collection of z-stacks three-dimensional reconstruction. Images were acquired from random positions of biofilms formed on the upper side of the coverslips. The thicknesses of biofilms were also determined directly from the confocal stack images.
The results were expressed as means ± SD. Analysis of variance (ANOVA) was conducted and differences between variables were tested for significance by one-way ANOVA with post hoc Tukey test using the SPSS V16.0 program. Differences at P < 0.05 were considered statistically significant. Correlation analysis was carried out using EXCEL program.
Physico-chemical characterization of A. auricula pigment
The A. auricula melanin exhibited the same, previously reported, physical and chemical properties as natural melanin (Bilinska 1996; Ellis and Griffiths 1974; Paim et al. 1990). It was insoluble in water, ethanol, hexane, acetone, benzene and chloroform, and dissolved only in alkali, precipitated in alkaline FeCl3 and below pH 3. A. auricula melanin was bleached in H2O2, KMnO4, K2Cr2O7 and NaOCl, and produced a blue color with FeSO4/ferricyanide.
The nature of the melanin was investigated further by UV, IR and EPR. In the UV spectrum, the absorbance of melanin first increased and then progressively decreased as the wavelength increased, in agreement with the results of other (Bell and Wheeler 1986). The absorption spectrum showed characteristic absorption peaks in the UV regions at 210 nm (Fig. 1), due to the presence of many complex conjugated structures in the melanin molecule (Cockell and Knowland 1999). The decrease in absorption with increasing wavelength is almost linear in the case of melanins. Hence, the slopes of linear plots are often used to identify melanins (Chet et al. 1967; Ellis and Griffiths 1974; Ravishankar et al. 1995). Daniel (1938) showed that the log of optical density of a melanin solution when plotted against wavelength produces a linear curve with negative slopes from −0.0015 to −0.0030 (Ellis and Griffiths 1974; Suryanarayanan et al. 2004). Such characteristic straight lines with negative slopes have been obtained for some terrestrial and marine fungi (Chet et al. 1967; Ellis and Griffiths 1974; Ravishankar et al. 1995). The melanin of Phyllosticta capitalensis gave a straight line with a negative slope of −0.0015 (Suryanarayanan et al. 2004). The pigment of A. auricula also gave a straight line with a negative slope of −0.0028 (Fig. 2).
IR spectra have been employed to study the structural peculiarities of melanin pigments (Bonner and Duncan 1962). The IR spectrum of the isolated melanin was in accordance with the results of Suryanarayanan et al. (2004), who found typical absorption bands of hydroxyl group at 3,287.6 cm−1, of N–H stretch at 2,925.8 cm−1 and of carboxylic groups at 1,702.3 cm−1 (Fig. 3).
Characteristic EPR behavior is another diagnostic feature of melanin according to the organic free radicals present (Enochs et al. 1993). The peak at 2.0042 (G value) of the EPR spectrum of A. auricula melanin (Fig. 4) indicated the presence of free radicals, as also reported by Enochs et al. (1993). Though these spectra were performed in an attempt to obtain structural information on melanin, it is still difficult to know the exact structure of melanin polymers (Selvakumar et al. 2008), which needs further investigation in the future.
Effects of A, auricula pigment on biofilm formation
The A. auricula melanin MIC values were 160 μg ml−1, 640 μg ml−1 and 320 μg ml−1 for E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3, respectively. Figure 5 shows the effects of A. auricula melanin on the formation of E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3 biofilms. Auricularia auricula melanin exhibited concentration-dependent inhibitory activity, which showed a reduction in biofilm biomass with the increase in concentration. As shown in Fig. 5, A. auricula melanin at a sub-MIC of 80 μg ml−1 inhibited biofilm formation of E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3 up to 71.3, 61.7 and 63.2%, respectively. Interestingly, A. auricula melanin inhibited biofilm formation of the three strains without inhibiting growth of their planktonic cells (Table 1), thus proving that biofilm inhibition by A. auricula melanin is not due to an antibacterial effect.
Image analysis of bacterial biofilms by CLSM
The effects on E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3 biofilms of A. auricula melanin were also studied using CLSM. CLSM z-section analyses showed that the three strains formed thick and compact biofilms when grown in the absence of A. auricula melanin. In contrast, A. auricula melanin at a sub-MIC of 80 μg ml−1 resulted in thinner and looser cell aggregations on surfaces instead of normal biofilm architecture (Figs. 6, 7). Besides the difference in biofilm thickness, A. auricula melanin also influenced the surface area covered. The CLSM top-view images of E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3 biofilms showed that the biofilms of control groups (without A. auricula melanin) covered the entire surface of the coverslips. In the presence of Auricularia auricula melanin at a concentration of 80 μg ml−1, CLSM assessments of the three bacteria revealed an obvious decrease in the surface coverage of coverslips, and the density of bacteria was decreased significantly (Fig. 6).
In this study, a pigment from A. auricula, which has been used as a delicious food in China for many years, was isolated and characterized. It was shown that A. auricula melanin inhibits QS-regulated biofilm formation in E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3 without interfering with their growth. A wide spectrum of QS-regulated behaviors, such as biofilm formation, has been reported in several bacteria (Waters et al. 2008). In our research, A. auricula melanin was found to inhibit biofilm formation at a range below MIC. The inhibitory effect was regulated by QS. A significant number of reports have appeared on the persistence of some foodborne pathogens on food contact surfaces and biofilms, leading to serious economic and health problems. Pathogen outbreaks associated with biofilms have been related to the presence of E. coli and Pseudomonas spp. (Hentzer et al. 2002; Herzberg et al. 2006). Effective control of these pathogenic bacteria and dental plaque is the key to the prevention and treatment of these diseases. Research may contribute to the prevention of bacterial diseases without raising further concerns about antibiotic resistance.
Melanin is a common substance produced by animals, plants and micro-organisms. Melanins are irregular, dark-brown polymers that are used frequently in medicine, pharmacology and cosmetics preparations (Casadevall et al. 2000; Dastager et al. 2006; Jacobson 2000; Langfelder et al. 2003). As shown in previous studies, melanin has a number of healthful functions, such as antioxidation (Tu et al. 2009), free radical-scavenging (Wu et al. 2008), anti-HIV (Manning et al. 2003) and immunomodulatory (Sava et al. 2001) activity. However, there is little information available in literature investigating the antibiofilm activity of melanin from A. auricula. In this study, a pigment from A. auricula was characterized as melanin based on UV, IR, EPR spectra and chemical tests. Biofilm formation in E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3 was regulated by QS. In this paper, A. auricula melanin inhibited QS-regulated biofilm formation in E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3 without interfering with the growth of these organisms. Biosynthesis of melanin with tyrosinase transforms the tyrosine into L-DOPA (3, 4-dihydroxy phenyl-l-alanine), which is further converted into dopachrome and auto-oxidized to indol-5,6-quinone. The latter is polymerized spontaneously into DOPA-melanin, which is a dark-brown pigment (Mencher and Heim 1962). Many heterocyclic compounds, e.g., dopaquinone, leucodopachrome and cysteinyldopas, participate in the whole pigment synthesis process. These intermediate compounds all contain carboxyl and amino groups that easily form a carbonyl group with heterocycle by intra- or inter-molecular dehydration. After dehydration, the conformation of the generating compound is similar to N-acyl homoserine lactone without the side chain. Presumably, these inhibitory compounds could inhibit acyl homoserine lactone (AHL)-regulated behaviors by binding competitively to the AHL receptor protein. This may explain why natural melanin from A. auricula can inhibit QS systems in bacteria. Because A. auricula has been used safely for a long time, the isolated melanin has a great advantage over the use of toxic compounds for humans. These findings suggest that melanin from A. auricula might have potential for application in clinical medicine and the food industry.
Acharya K, Samui K, Rai M, Dutta B, Achary R (2004) Antioxidant and nitric oxide synthase activation properties of Auricularia auricula. Indian J Exp Biol 42:538–540
Bell AA, Wheeler MH (1986) Biosynthesis and functions of fungal melanins. Annu Rev Phytopathol 24:411–451
Berney M, Hammes F, Bosshard F, Weilenmann HU, Egli T (2007) Assessment and interpretation of bacterial viability by using the LIVE/DEAD BacLight Kit in combination with flow cytometry. Appl Environ Microbiol 73:3283–3290
Bilinska B (1996) Progress of infrared investigations of melanin structures. Spectrochim Acta A 52:1157–1162
Bonner TG, Duncan A (1962) Infrared spectra of some melanins. Nature 194:1078–1079
Brooun A, Liu SH, Lewis K (2000) A dose-response study of antibiotic resistance in Pseudomonas aeruginosa biofilms. Antimicrob Agents Ch 44:640–646
Camilli A, Bassler BL (2006) Bacterial small-molecule signaling pathways. Science 311:1113–1116
Casadevall A, Rosas AL, Nosanchuk JD (2000) Melanin and virulence in Cryptococcus neoformans. Curr Opin Microbiol 3:354–358
Chet I, Henis Y, Mitchell R (1967) Chemical composition of hyphal and sclerotial walls of Sclerotium rolfsii Sacc. Can J Bot 13:137–141
Cheung PCK (1996) The hypocholesterolemic effect of two edible mushrooms: Auricularia auricula (tree-ear) and Tremella fuciformis (white jelly-leaf ) in hypercholesterolemic rats. Nutr Res 16:1721–1725
Cockell CS, Knowland J (1999) Ultraviolet radiation screening compounds. Biol Rev 74:311–345
Costerton JW, Stewart PS, Greenberg EP (1999) Bacterial biofilms: a common cause of persisitent infections. Science 284:1318–1322
Daniel J (1938) Studies of multiple allelomorphic series in the house mouse. 111. A spectrophotometricstudy of mouse melanin. J Genet 36:139–143
Dastager SG, Li WJ, Dayanand A, Tang SK, Tian XP, Zhi XY, Xu LH, Jiang CL (2006) Separation, identification and analysis of pigment (melanin) production in Streptomyces. Afr J Biotechnol 5:1131–1134
Domka J, Lee J, Bansal T, Wood TK (2007) Temporal gene-expression in Escherichia coli K-12 biofilms. Environ Microbiol 9:332–346
Ellis DH, Griffiths DA (1974) The location and analysis of melanin in the cell walls of some soil fungi. Can J Microbiol 20:1379–1386
Enochs WS, Nilges MJ, Swartz HW (1993) A standardized test for the identification and characterization of melanins using electron paramagnetic resonance (EPR) spectroscopy. Pigm Cell Res 6:91–99
Finkel T, Holbrook NJ (2000) Oxidants, oxidative stress and the biology of aging. Nature 408:239–247
Girennavar B, Cepeda ML, Soni KA, Vikram A, Jesudhasan P, Jayaprakasha, Pillai SD, Patil BS (2008) Grapefruit juice and its furocoumarins inhibits autoinducer signaling and biofilm formation in bacteria. Int J Food Microbiol 125:204–208
Hentzer M, Riedel K, Rasmussen TB, Heydorn A, Andersen JB, Parsek MR, Rice SA, Eberl L, Molin S, Høiby N, Kjelleberg S, Givskov M (2002) Inhibition of quorum sensing in Pseudomonas aeruginosa biofilm bacteria by a halogenated furanone compound. Microbiology 148:87–102
Herzberg M, Kaye IK, Peti W, Wood TK (2006) YdgG (TqsA) controls biofilm formation in Escherichia coli K-12 through autoinducer 2 transport. J Bacteriol 188:587–598
Jacobson ES (2000) Pathogenic roles for fungal melanins. Clin Microbiol Rev 13:708–717
Khan MS, Zahin M, Hasan S, Husain FM, Ahmad I (2009) Inhibition of quorum sensing regulated bacterial functions by plant essential oils with special reference to clover oil. Lett Appl Microbiol 49:354–360
Langfelder K, Streibel M, Jahn B, Haase G, Brakhage AA (2003) Biosynthesis of fungal melanins and their importance for human pathogenic fungi. Fungal Genet Biol 38:143–158
Manning JT, Bundred PE, Henzi P (2003) Melanin and HIV in sub-Saharan Africa. J Theor Biol 223:131–133
Mencher JR, Heim AH (1962) Melanin biosynthesis by Streptomyces lavendulae. J Gen Microbiol 28:665–670
Misaki A, Kakuta M, Sasaki T, Tanaka M, Miyaji H (1981) Studies on interrelation of structure and antitumor effects of polysaccharides: antitumor action of periodatemodified, branched (1 goes to 3)-beta-d-glucan of Auricularia auricula-juade, and other polysaccharides containing (1 goes 3)-glycosidic linkages. Carbohyd Res 92:115–129
Mizuno T, Saito H, Nishitoba T, Kawagishi H (1995) Antitumoractive substances from mushrooms. Food Rev Int 11:23–61
Paim S, Linhares LF, Magrich AS, Martin JP (1990) Characterization of fungal melanins and soil humic acids by chemical analysis and infrared spectroscopy. Biol Fertil Soils 10:72–76
Percival SL, Cutting KF (2009) Biofilms: possible strategies for suppression in chronic wounds. Nurs Stand 23:64–68
Rasmussen TB, Givskov M (2006) Quorum sensing inhibitors: a bargain of effects. Microbiology 152:895–904
Rasmussen TB, Bjarnsholt T, Skindersoe ME, Hentzer M, Kristoffersen P, Köte M, Nielsen J, Eberl L, Givskov M (2005) Screening for quorum-sensing inhibitors (QSI) by use of a novel genetic system, the QSI selector. J Bacteriol 187:1799–1814
Ravishankar JP, Muruganandam V, Suryanarayanan TS (1995) Isolation and characterization of melanin from a marine fungus. Bot Mar 38:413–416
Sava VM, Galkin BN, Hong MY, Yang PC, Huang GS (2001) A novel melaninlike pigment derived from black tea leaves with immuno-stimulating activity. Food Res Int 34:337–343
Selvakumar P, Rajasekar S, Periasamy K, Raaman N (2008) Isolation and characterization of melanin pigment from Pleurotus cystidiosus (telomorph of Antromycopsis macrocarpa). World J Microbiol Biotechnol 24:2125–2131
Suryanarayanan TS, Ravishankar JP, Venkatesan G, Murali TS (2004) Characterization of the melanin pigment of a cosmopolitan fungal endophyte. Mycol Res 108:974–978
Takeujchi H, He P, Mooi L (2004) Reductive effect of hot- water extracts from woody ear (Auricularia auricula-juade Quel.) on food intake and blood glucose concentration in genetically diabetic KK-Ay mice. J Nutr Sci Vitaminol (Tokyo) 50:300–304
Tu Y, Sun Y, Tian Y, Xie M, Chen J (2009) Physicochemical characterisation and antioxidant activity of melanin from the muscles of Taihe Black-bone silky fowl (Gallus gallus domesticus Brisson). Food Chem 114:1345–1350
Wang Y, Dai Y, Zhang Y, Hu YB, Yang BY, Chen SY (2007) Effects of quorum sensing autoinducer degradation gene on virulence and biofilm formation of Pseudomonas aeruginosa. Sci China Ser C-Life Sci 50:385–391
Waters CM, Lu W, Rabinowitz JD, Bassler BL (2008) Quorum sensing controls biofilm formation in Vibrio cholerae through modulation of cyclic di-GMP levels and repression of vpsT. J Bacteriol 190:2527–2536
Wu Y, Shan L, Yang S, Ma A (2008) Identification and antioxidant activity of melanin isolated from Hypoxylon archeri, a companion fungus of Tremella fuciformis. J Basic Microb 48:217–221
Yoon SJ, Yu MA, Pyun YR, Hwang JK, Chu DC, Juneja LR, Mourão PA (2003) The nontoxic mushroom Auricularia auricula contains a polysaccharide with anticoagulant activity mediated by antithrombin. Thromb Res 112:151–158
Zhang L, Yang L, Ding Q, Chen XF (1995) Studies on molecular weights of polysaccharides of Auricularia auricula-juade. Carbohyd Res 270:1–10
Zhu H, He CC, Chu QH (2011) Inhibition of quorum sensing in Chromobacterium violaceum by pigments extracted from Auricularia auricular. Lett Appl Microbiol 52(3):269–274
This work was supported by Natural Science Foundation of China (No.30700627) and Agricultural Science Independent Innovation Fund of Jiangsu [No.CX (08) 113].
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Bin, L., Wei, L., Xiaohong, C. et al. In vitro antibiofilm activity of the melanin from Auricularia auricula, an edible jelly mushroom. Ann Microbiol 62, 1523–1530 (2012). https://doi.org/10.1007/s13213-011-0406-3
- Auricularia auricula
- Escherichia coli
- Pseudomonas aeruginosa
- Pseudomonas fluorescens