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Characterization of bacteria in ballast water using MALDI-TOF mass spectrometry.

Emami K, Askari V, Ullrich M, Mohinudeen K, Anil AC, Khandeparker L, Burgess JG, Mesbahi E - PLoS ONE (2012)

Bottom Line: To evaluate a rapid and cost-effective method for monitoring bacteria in ballast water, several marine bacterial isolates were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).Seawater samples collected from the North Sea were incubated in steel ballast tanks and the presence of potentially harmful species of Pseudomonas was also investigated.At the genus-level, the identification of thirty six isolates using MALDI-TOF MS produced similar results to those obtained by 16S rRNA gene sequencing.

View Article: PubMed Central - PubMed

Affiliation: School of Biology, Newcastle University, Newcastle upon Tyne, United Kingdom. kaveh.emami@ncl.ac.uk

ABSTRACT
To evaluate a rapid and cost-effective method for monitoring bacteria in ballast water, several marine bacterial isolates were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Since International Maritime Organization (IMO) regulations are concerned with the unintended transportation of pathogenic bacteria through ballast water, emphasis was placed on detecting species of Vibrio, enterococci and coliforms. Seawater samples collected from the North Sea were incubated in steel ballast tanks and the presence of potentially harmful species of Pseudomonas was also investigated. At the genus-level, the identification of thirty six isolates using MALDI-TOF MS produced similar results to those obtained by 16S rRNA gene sequencing. No pathogenic species were detected either by 16S rRNA gene analysis or by MALDI-TOF MS except for the opportunistically pathogenic bacterium Pseudomonas aeruginosa. In addition, in house software that calculated the correlation coefficient values (CCV) of the mass spectral raw data and their variation was developed and used to allow the rapid and efficient identification of marine bacteria in ballast water for the first time.

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Comparison of Pseudomonas stutzeri and Proteus vulgaris MALDI-TOF mass spectra.Isolates S04, S24 and S38 were identified as P. stutzeri through 16S rRNA gene sequencing; however isolate S24 showed a different peak pattern and was identified as Proteus vulgaris by the Biotyper software. Examples of common peaks are indicated by vertical lines and unique peaks are indicated by the arrows.
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pone-0038515-g008: Comparison of Pseudomonas stutzeri and Proteus vulgaris MALDI-TOF mass spectra.Isolates S04, S24 and S38 were identified as P. stutzeri through 16S rRNA gene sequencing; however isolate S24 showed a different peak pattern and was identified as Proteus vulgaris by the Biotyper software. Examples of common peaks are indicated by vertical lines and unique peaks are indicated by the arrows.

Mentions: Isolate S04 was identified as Pseudomonas stutzeri by both MTB and 16S rRNA gene sequencing. Isolate S24 was also identified as Pseudomonas stutzeri by 16S rRNA gene analysis whereas by MTB, this isolate was identified as Proteus vulgaris. The mass-spectrum of isolate S04, was compared with that of isolate S24 (Figure 8) showing that, although there are common peaks between the two isolates, there are also clear differences that separate them as two different genera. For example, S24 has more peaks in the higher m/z range than S04. They both had an m/z 7272 peak but the m/z 6624–25 peak was missing in the S24 isolate mass spectrum and peaks at m/z 6273 and 5510 in S24 were missing in S04. Therefore it appears that the MTB method is providing more reliable information on a strain’s identity. The mass-spectrum of isolate S24 showed relatively high relatedness to a Proteus vulgaris isolate in the study by Fernandez-No et al. [37] who used MALDI-TOF MS to characterize food-borne pathogens (Table 2, Fig. 8). Although the m/z 6265 and 6499 peaks were missing in S24, the maximum difference observed between the other 11 peaks was only ±3 Da. It is important to note that Fernandez-No et al. [38] used a different mass spectrometer (Voyager DE STR, Applied Biosystems) and followed a different protocol for sample preparation. These experimental differences on the one hand and the broad concurrence of data on the other further demonstrate the high level of reproducibility of the MTB method.


Characterization of bacteria in ballast water using MALDI-TOF mass spectrometry.

Emami K, Askari V, Ullrich M, Mohinudeen K, Anil AC, Khandeparker L, Burgess JG, Mesbahi E - PLoS ONE (2012)

Comparison of Pseudomonas stutzeri and Proteus vulgaris MALDI-TOF mass spectra.Isolates S04, S24 and S38 were identified as P. stutzeri through 16S rRNA gene sequencing; however isolate S24 showed a different peak pattern and was identified as Proteus vulgaris by the Biotyper software. Examples of common peaks are indicated by vertical lines and unique peaks are indicated by the arrows.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3369924&req=5

pone-0038515-g008: Comparison of Pseudomonas stutzeri and Proteus vulgaris MALDI-TOF mass spectra.Isolates S04, S24 and S38 were identified as P. stutzeri through 16S rRNA gene sequencing; however isolate S24 showed a different peak pattern and was identified as Proteus vulgaris by the Biotyper software. Examples of common peaks are indicated by vertical lines and unique peaks are indicated by the arrows.
Mentions: Isolate S04 was identified as Pseudomonas stutzeri by both MTB and 16S rRNA gene sequencing. Isolate S24 was also identified as Pseudomonas stutzeri by 16S rRNA gene analysis whereas by MTB, this isolate was identified as Proteus vulgaris. The mass-spectrum of isolate S04, was compared with that of isolate S24 (Figure 8) showing that, although there are common peaks between the two isolates, there are also clear differences that separate them as two different genera. For example, S24 has more peaks in the higher m/z range than S04. They both had an m/z 7272 peak but the m/z 6624–25 peak was missing in the S24 isolate mass spectrum and peaks at m/z 6273 and 5510 in S24 were missing in S04. Therefore it appears that the MTB method is providing more reliable information on a strain’s identity. The mass-spectrum of isolate S24 showed relatively high relatedness to a Proteus vulgaris isolate in the study by Fernandez-No et al. [37] who used MALDI-TOF MS to characterize food-borne pathogens (Table 2, Fig. 8). Although the m/z 6265 and 6499 peaks were missing in S24, the maximum difference observed between the other 11 peaks was only ±3 Da. It is important to note that Fernandez-No et al. [38] used a different mass spectrometer (Voyager DE STR, Applied Biosystems) and followed a different protocol for sample preparation. These experimental differences on the one hand and the broad concurrence of data on the other further demonstrate the high level of reproducibility of the MTB method.

Bottom Line: To evaluate a rapid and cost-effective method for monitoring bacteria in ballast water, several marine bacterial isolates were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS).Seawater samples collected from the North Sea were incubated in steel ballast tanks and the presence of potentially harmful species of Pseudomonas was also investigated.At the genus-level, the identification of thirty six isolates using MALDI-TOF MS produced similar results to those obtained by 16S rRNA gene sequencing.

View Article: PubMed Central - PubMed

Affiliation: School of Biology, Newcastle University, Newcastle upon Tyne, United Kingdom. kaveh.emami@ncl.ac.uk

ABSTRACT
To evaluate a rapid and cost-effective method for monitoring bacteria in ballast water, several marine bacterial isolates were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Since International Maritime Organization (IMO) regulations are concerned with the unintended transportation of pathogenic bacteria through ballast water, emphasis was placed on detecting species of Vibrio, enterococci and coliforms. Seawater samples collected from the North Sea were incubated in steel ballast tanks and the presence of potentially harmful species of Pseudomonas was also investigated. At the genus-level, the identification of thirty six isolates using MALDI-TOF MS produced similar results to those obtained by 16S rRNA gene sequencing. No pathogenic species were detected either by 16S rRNA gene analysis or by MALDI-TOF MS except for the opportunistically pathogenic bacterium Pseudomonas aeruginosa. In addition, in house software that calculated the correlation coefficient values (CCV) of the mass spectral raw data and their variation was developed and used to allow the rapid and efficient identification of marine bacteria in ballast water for the first time.

Show MeSH
Related in: MedlinePlus