A genomic and transcriptomic approach to investigate the blue pigment phenotype in Pseudomonas fluorescens

Andreani, Nadia and Carraro, Lisa and Martino, Maria Elena and Fondi, Marco and Fasolato, Luca and Miotto, Giovanni and Magro, Massimiliano and Vianello, Fabio and Cardazzo, Barbara (2015) A genomic and transcriptomic approach to investigate the blue pigment phenotype in Pseudomonas fluorescens. International Journal of Food Microbiology, 213 . pp. 88-98. ISSN 0168-1605

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Abstract

Pseudomonas fluorescens is a well-known food spoiler, able to cause serious economic losses in the food industry due to its ability to produce many extracellular, and often thermostable, compounds. The most outstanding spoilage events involving P. fluorescens were blue discoloration of several food stuffs, mainly dairy products. The bacteria involved in such high-profile cases have been identified as belonging to a clearly distinct phylogenetic cluster of the P. fluorescens group. Although the blue pigment has recently been investigated in several studies, the biosynthetic pathway leading to the pigment formation, as well as its chemical nature, remain challenging and unsolved points.
In the present paper, genomic and transcriptomic data of 4 P. fluorescens strains (2 blue-pigmenting strains and 2 non-pigmenting strains) were analyzed to evaluate the presence and the expression of blue strain-specific genes. In particular, the pangenome analysis showed the presence in the blue-pigmenting strains of two copies of genes involved in the tryptophan biosynthesis pathway (including trpABCDF). The global expression profiling of blue-pigmenting strains versus non-pigmenting strains showed a general up-regulation of genes involved in iron uptake and a down-regulation of genes involved in primary metabolism. Chromogenic reaction of the blue-pigmenting bacterial cells with Kovac's reagent indicated an indole-derivative as the precursor of the blue pigment. Finally, solubility tests and MALDI-TOF mass spectrometry analysis of the isolated pigment suggested that its molecular structure is very probably a hydrophobic indigo analog.

Keywords:Pseudomonas fluorescens, Comparative genomics and transcriptomics, Blue mozzarella, JCNotOpen
Subjects:C Biological Sciences > C510 Applied Microbiology
D Veterinary Sciences, Agriculture and related subjects > D610 Food Science
C Biological Sciences > C500 Microbiology
Divisions:College of Science > School of Life Sciences
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ID Code:27504
Deposited On:19 May 2017 09:20

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