MyMedR

Exochelin production in Mycobacterium neoaurum

Chan KG

Int J Mol Sci, 2009 Jan;10(1):345-53.

PMID: 19333449

Mycobacterium neoaurum is a soil saprophyte and obligate aerobic bacterium. This group of mycobacterium is relatively fast-growing. They form colonies on nutrient agar at 37 masculineC within 3 - 4 days. In natural soil habitats, bioavailability of iron is limited. To facilitate iron uptake, most mycobacteria produce siderophores. One example is exochelin, which is extracellular and water-soluble. In this report, the production of exochelin in M. neoaurum was induced in iron-deficiency, but repressed under ironsufficiency growth conditions. It is however not induced under zinc-deficiency growth conditions. The growth of this mycobacterium was correlated with exochelin secretion under iron-deficiency culture conditions. When M. neoaurum was grown in defined medium containing 0.04 microg Fe(III)/mL (final concentration), the production of exochelin reached a maximum and the corresponding cell growth was comparable to that under iron-sufficiency conditions. In this study, exochelin was purified from spent supernatant of M. neoaurum by semi-preparative chromatography. When saturated ferric chloride solution was added into the purified exochelin, a ferri-exochelin complex was formed. It is proposed that iron uptake in M. neoaurum is exochelin-mediated.

A novel medium for the isolation of N-acylhomoserine lactone-degrading bacteria

Chan KG, Yin WF, Sam CK, Koh CL

J Ind Microbiol Biotechnol, 2009 Feb;36(2):247-51.

PMID: 18946694 DOI: 10.1007/s10295-008-0491-x

A novel chemically defined medium, named KG medium, supplemented with N-3-oxo-hexanoylhomoserine lactone (3-oxo-C6-HSL), an acylhomoserine lactone (AHL) used as signalling molecules in Gram-negative bacterial cell-to-cell communication, as the sole source of carbon and nitrogen, was designed and successfully used for the enrichment and isolation of AHL-degrading bacteria. A 3-oxo-C6-HSL-degrading bacterium, 13sw7, was isolated from sewage after six enrichment transfers in the 3-oxo-C6-HSL-containing KG medium. On the basis of the almost complete 16S ribosomal DNA sequence, isolate 13sw7 was clustered with unculturable beta-proteobacteria. This study indicates that the AHL-containing KG medium is effective in isolating AHL-degrading bacteria, including those previously considered unculturable, from environmental sources. To the best of our knowledge, this is the first documentation of the isolation of an AHL-degrading proteobacterium from sewage.

Fulltext Microbial contamination of orthodontic buccal tubes from manufacturers

Purmal K, Chin S, Pinto J, Yin WF, Chan KG

Int J Mol Sci, 2010 Sep 16;11(9):3349-56.

PMID: 20957099 DOI: 10.3390/ijms11093349

This study aimed to test the sterility of new unused orthodontic buccal tubes received from manufacturers. Four different types of buccal tubes were used straight from the manufactures package without any additional sterilizing step. Of these buccal tubes tested, three genera of bacteria, implicated as opportunistic pathogens, namely Micrococcus luteus, Staphylococcus haemolyticus and Acinetobacter calcoaceticus were recovered from these buccal tubes. Our data showing microbial contamination on buccal tubes highlights the need of sterilization before clinical use. We also suggest that manufacturers should list the sterility state of orthodontic buccal tubes on their packaging or instructions stating the need for sterilization.

Rapid degradation of N-3-oxo-acylhomoserine lactones by a Bacillus cereus isolate from Malaysian rainforest soil

Chan KG, Wong CS, Yin WF, Sam CK, Koh CL

Antonie Van Leeuwenhoek, 2010 Oct;98(3):299-305.

PMID: 20376561 DOI: 10.1007/s10482-010-9438-0

A bacterial strain, KM1S, was isolated from a Malaysian rainforest soil sample by using a defined enrichment medium that specifically facilitates selection of quorum quenching bacteria. KM1S was clustered closely to Bacillus cereus by 16S ribosomal DNA sequence analysis. It degraded N-3-oxo-hexanoyl homoserine lactone and N-3-oxo-octanoyl homoserine lactone in vitro rapidly at 4.98 and 6.56 microg AHL h(-1) per 10(9) CFU/ml, respectively, as determined by the Rapid Resolution Liquid Chromatography. The aiiA homologue, encoding an autoinducer inactivation enzyme catalyzing the degradation of N-acylhomoserine lactones, of KM1S was amplified and cloned. Sequence analysis indicated the presence of the motif (106)HXDH-59 amino acids-H(169)-21 amino acids-D(191) for N-acylhomoserine lactone lactonases.

Quorum sensing in Aeromonas species isolated from patients in Malaysia

Chan KG, Puthucheary SD, Chan XY, Yin WF, Wong CS, Too WS, et al.

Curr Microbiol, 2011 Jan;62(1):167-72.

PMID: 20544198 DOI: 10.1007/s00284-010-9689-z

Bacterial quorum sensing signal molecules called N-acylhomoserine lactone (AHL) controls the expression of virulence determinants in many Gram-negative bacteria. We determined AHL production in 22 Aeromonas strains isolated from various infected sites from patients (bile, blood, peritoneal fluid, pus, stool and urine). All isolates produced the two principal AHLs, N-butanoylhomoserine lactone (C4-HSL) and N-hexanoyl homoserine lactone (C6-HSL). Ten isolates also produced additional AHLs. This report is the first documentation of Aeromonas sobria producing C6-HSL and two additional AHLs with N-acyl side chain longer than C(6). Our data provides a better understanding of the mechanism(s) of this environmental bacterium emerging as a human pathogen.

Fulltext Characterization of N-acylhomoserine lactone-degrading bacteria associated with the Zingiber officinale (ginger) rhizosphere: co-existence of quorum quenching and quorum sensing in Acinetobacter and Burkholderia

Chan KG, Atkinson S, Mathee K, Sam CK, Chhabra SR, Cámara M, et al.

BMC Microbiol, 2011 Mar 08;11:51.

PMID: 21385437 DOI: 10.1186/1471-2180-11-51

BACKGROUND: Cell-to-cell communication (quorum sensing (QS)) co-ordinates bacterial behaviour at a population level. Consequently the behaviour of a natural multi-species community is likely to depend at least in part on co-existing QS and quorum quenching (QQ) activities. Here we sought to discover novel N-acylhomoserine lactone (AHL)-dependent QS and QQ strains by investigating a bacterial community associated with the rhizosphere of ginger (Zingiber officinale) growing in the Malaysian rainforest.

RESULTS: By using a basal growth medium containing N-(3-oxohexanoyl)homoserine lactone (3-oxo-C6-HSL) as the sole source of carbon and nitrogen, the ginger rhizosphere associated bacteria were enriched for strains with AHL-degrading capabilities. Three isolates belonging to the genera Acinetobacter (GG2), Burkholderia (GG4) and Klebsiella (Se14) were identified and selected for further study. Strains GG2 and Se14 exhibited the broadest spectrum of AHL-degrading activities via lactonolysis while GG4 reduced 3-oxo-AHLs to the corresponding 3-hydroxy compounds. In GG2 and GG4, QQ was found to co-exist with AHL-dependent QS and GG2 was shown to inactivate both self-generated and exogenously supplied AHLs. GG2, GG4 and Se14 were each able to attenuate virulence factor production in both human and plant pathogens.

CONCLUSIONS: Collectively our data show that ginger rhizosphere bacteria which make and degrade a wide range of AHLs are likely to play a collective role in determining the QS-dependent phenotype of a polymicrobial community.

Malabaricone C from Myristica cinnamomea exhibits anti-quorum sensing activity

Chong YM, Yin WF, Ho CY, Mustafa MR, Hadi AH, Awang K, et al.

J Nat Prod, 2011 Oct 28;74(10):2261-4.

PMID: 21910441 DOI: 10.1021/np100872k

A methanol-soluble extract of the bark of Myristica cinnamomea was found to exhibit anti-quorum sensing activity, and subsequent bioassay-guided isolation led to the identification of the active compound malabaricone C (1). Compound 1 inhibited violacein production by Chromobacterium violaceum CV026 when grown in the presence of a cognate signaling molecule, N-3-oxohexanoyl-homoserine lactone. Furthermore, 1 inhibited the quorum sensing-regulated pyocyanin production and biofilm formation in Pseudomonas aeruginosa PAO1. These results suggest that the anti-quorum sensing activity of 1 and related molecules should be investigated further.

Characterization of wetland quorum quenching Pseudomonas aeruginosa strain 2SW8 and its 2-heptyl-3-hydroxy-4-quinolone production

Wong CS, Yin WF, Sam CK, Koh CL, Chan KG

New Microbiol., 2012 Jan;35(1):43-51.

PMID: 22378552

Most Proteobacteria produce N-acylhomoserine lactones for bacterial cell-to-cell communication, a process called quorum sensing. Interference of quorum sensing, commonly known as quorum quenching, represents an important way to control quorum sensing. This work reports the isolation of quorum quenching bacterium strain 2WS8 from Malaysia tropical wetland water (2°11'8"N, 102°15'2"E, in 2007) by using a modified version of a previously reported KG medium. Strain 2WS8 was isolated based on its ability to utilize N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL) as the sole source of energy. This bacterium clustered closely to Pseudomonas aeruginosa PAO1. Strain 2SW8 possesses both quiP and pvdQ homologue acylase genes. Rapid Resolution Liquid Chromatography analysis confirmed that strain 2SW8 preferentially degraded N-acylhomoserine lactones with 3-oxo group substitution but not those with unsubstituted groups at C3 position in the acyl side chain. Strain 2SW8 also showed 2-heptyl-3-hydroxy-4-quinolone production.

Coexistence of quorum-quenching and quorum-sensing in tropical marine Pseudomonas aeruginosa strain MW3A

Wong CS, Yin WF, Choo YM, Sam CK, Koh CL, Chan KG

World J Microbiol Biotechnol, 2012 Feb;28(2):453-61.

PMID: 22806840 DOI: 10.1007/s11274-011-0836-x

A chemically defined medium called KGm medium was used to isolate from a sample of sea water a bacterial strain, MW3A, capable of using N-3-oxohexanoyl-L: -homoserine lactone as the sole carbon source. MW3A was clustered closely to Pseudomonas aeruginosa by 16S ribosomal DNA sequence analysis. It degraded both N-acylhomoserine lactones (AHLs) with a 3-oxo group substitution and, less preferably, AHLs with unsubstituted groups at C3 position in the acyl side chain, as determined by Rapid Resolution Liquid Chromatography. Its quiP and pvdQ homologue gene sequences showed high similarities to those of known acylases. Spent supernatant of MW3A harvested at 8-h post inoculation was shown to contain long-chain AHLs when assayed with the biosensor Escherichia coli [pSB1075], and specifically N-dodecanoyl-L: -homoserine lactone and N-3-oxotetradecanoyl-L: -homoserine lactone by high resolution mass spectrometry. Hence, we report here a novel marine P. aeruginosa strain MW3A possessing both quorum-quenching and quorum-sensing properties.

Fulltext Heavy-metal resistance of a France vineyard soil bacterium, Pseudomonas mendocina strain S5.2, revealed by whole-genome sequencing

Chong TM, Yin WF, Mondy S, Grandclément C, Dessaux Y, Chan KG

J Bacteriol, 2012 Nov;194(22):6366.

PMID: 23105092 DOI: 10.1128/JB.01702-12

Here we present the draft genome of Pseudomonas mendocina strain S5.2, possessing tolerance to a high concentration of copper. In addition to being copper resistant, the genome of P. mendocina strain S5.2 contains a number of heavy-metal-resistant genes known to confer resistance to multiple heavy-metal ions.

Fulltext Draft genome sequence of an Aeromonas sp. strain 159 clinical isolate that shows quorum-sensing activity

Chan XY, Chua KH, Puthucheary SD, Yin WF, Chan KG

J Bacteriol, 2012 Nov;194(22):6350.

PMID: 23105081 DOI: 10.1128/JB.01642-12

Aeromonas is a pathogenic organism that is often found to infect humans. Here we report the draft genome of a clinical isolate in Malaysia, Aeromonas sp. strain 159, which shows N-acylhomoserine lactone production. In the draft genome of strain 159, luxI and luxR homologue genes were found to be located at contig 47, and these genes are believed to be important for the quorum-sensing system present in this pathogen.

Fulltext Genome sequence of Dyella japonica strain A8, a quorum-quenching bacterium that degrades N-acylhomoserine lactones, isolated from Malaysian tropical soil

Chen JW, Chan KG

J Bacteriol, 2012 Nov;194(22):6331.

PMID: 23105069 DOI: 10.1128/JB.01637-12

Dyella japonica strain A8 is a Malaysian tropical soil bacterial strain which shows N-acylhomoserine lactone-degrading activity. Here, we present its draft genome sequence. A putative quorum-quenching gene was identified based on the genome sequence analysis of strain A8. To the best of our knowledge, this is the first genome announcement of a member from the genus of Dyella, and this is also the first work that reports the quorum-quenching activity of Dyella japonica.

Fulltext Whole-genome sequence of Cupriavidus sp. strain BIS7, a heavy-metal-resistant bacterium

Hong KW, Thinagaran Da, Gan HM, Yin WF, Chan KG

J Bacteriol, 2012 Nov;194(22):6324.

PMID: 23115161 DOI: 10.1128/JB.01608-12

Cupriavidus sp. strain BIS7 is a Malaysian tropical soil bacterium that exhibits broad heavy-metal resistance [Co(II), Zn(II), Ni(II), Se(IV), Cu(II), chromate, Co(III), Fe(II), and Fe(III)]. It is particularly resistant to Fe(II), Fe(III), and Zn(II). Here we present the assembly and annotation of its genome.

Fulltext Whole-genome sequence of N-acylhomoserine lactone-synthesizing and -degrading Acinetobacter sp. strain GG2

Hong KW, Koh CL, Sam CK, Yin WF, Chan KG

J Bacteriol, 2012 Nov;194(22):6318.

PMID: 23105061 DOI: 10.1128/JB.01579-12

Acinetobacter sp. strain GG2 is a quorum-sensing and quorum-quenching bacterium isolated from the ginger rhizosphere. It degrades a broad range of N-acylhomoserine lactone molecules via lactonase. The genome sequence of strain GG2 may provide insights on the regulation of quorum-sensing and quorum-quenching mechanisms in this bacterium.

Fulltext Complete genome sequence of Burkholderia sp. Strain GG4, a betaproteobacterium that reduces 3-oxo-N-acylhomoserine lactones and produces different N-acylhomoserine lactones

Hong KW, Koh CL, Sam CK, Yin WF, Chan KG

J Bacteriol, 2012 Nov;194(22):6317.

PMID: 23105060 DOI: 10.1128/JB.01578-12

Burkholderia sp. strain GG4, isolated from the ginger rhizosphere, possesses a unique N-acylhomoserine lactone (AHL)-modifying activity that reduces 3-oxo-AHLs to 3-hydroxy-AHLs. To the best of our knowledge, this is the first sequenced genome from a bacterium of the genus Burkholderia that shows both quorum-sensing and signaling confusion activities.

Fulltext Whole-genome sequence of Enterobacter sp. strain SST3, an endophyte isolated from Jamaican sugarcane (Saccharum sp.) stalk tissue

Gan HM, McGroty SE, Chew TH, Chan KG, Buckley LJ, Savka MA, et al.

J Bacteriol, 2012 Nov;194(21):5981-2.

PMID: 23045495 DOI: 10.1128/JB.01469-12

Enterobacter sp. strain SST3 is an endophytic bacterium isolated from Saccharum spp. Here we present its annotated draft genome that may shed light on its role as a bacterial endophyte of sugarcane. To our knowledge, this is the first genome announcement of a sugarcane-associated bacterium from the genus Enterobacter.

Fulltext Genome sequence of Roseomonas sp. strain B5, a quorum-quenching N-acylhomoserine lactone-degrading bacterium isolated from Malaysian tropical soil

Chen JW, Gan HM, Yin WF, Chan KG

J Bacteriol, 2012 Dec;194(23):6681-2.

PMID: 23144419 DOI: 10.1128/JB.01866-12

Roseomonas sp. strain B5 was isolated from Malaysian tropical soil that showed N-acylhomoserine lactone degradation. This is the first genome announcement of a member from the genus of Roseomonas and the first report on the quorum-quenching activity of Roseomonas spp.

Fulltext Insights from the genome sequence of quorum-quenching Staphylococcus sp. strain AL1, isolated from traditional Chinese soy sauce brine fermentation

Chong TM, Tung HJ, Yin WF, Chan KG

J Bacteriol, 2012 Dec;194(23):6611-2.

PMID: 23144375 DOI: 10.1128/JB.01669-12

We report the draft genome sequence of Staphylococcus sp. strain AL1, which degrades quorum-sensing molecules (namely, N-acyl homoserine lactones). To the best of our knowledge, this is the first documentation that reports the whole genome sequence and quorum-quenching activity of Staphylococcus sp. strain AL1.

Fulltext Draft genome sequence of Pantoea sp. strain A4, a Rafflesia-associated bacterium that produces N-acylhomoserine lactones as quorum-sensing molecules

Hong KW, Gan HM, Low SM, Lee PK, Chong YM, Yin WF, et al.

J Bacteriol, 2012 Dec;194(23):6610.

PMID: 23144374 DOI: 10.1128/JB.01619-12

Pantoea sp. strain A4 is a Gram-negative bacterium isolated from the Rafflesia flower. We present here, for the first time, the genome sequence of Rafflesia-associated Pantoea sp. strain A4, which exhibited quorum-sensing activity.

Fulltext Characterization of quorum sensing and quorum quenching soil bacteria isolated from Malaysian tropical montane forest

Chong TM, Koh CL, Sam CK, Choo YM, Yin WF, Chan KG

Sensors (Basel), 2012;12(4):4846-59.

PMID: 22666062 DOI: 10.3390/s120404846

We report the production and degradation of quorum sensing N-acyl-homoserine lactones by bacteria isolated from Malaysian montane forest soil. Phylogenetic analysis indicated that these isolates clustered closely to the genera of Arthrobacter, Bacillus and Pseudomonas. Quorum quenching activity was detected in six isolates of these three genera by using a series of bioassays and rapid resolution liquid chromatography analysis. Biosensor screening and high resolution liquid chromatography-mass spectrometry analysis revealed the production of N-dodecanoyl-L-homoserine lactone (C12-HSL) by Pseudomonas frederiksbergensis (isolate BT9). In addition to degradation of a wide range of N-acyl-homoserine lactones, Arthrobacter and Pseudomonas spp. also degraded p-coumaroyl-homoserine lactone. To the best of our knowledge, this is the first documentation of Arthrobacter and Pseudomonas spp. capable of degrading p-coumaroyl-homoserine lactone and the production of C12-HSL by P. frederiksbergensis.

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