Genomic Features of a Food-Derived Pseudomonas aeruginosa Strain PAEM and Biofilm-Associated Gene Expression under a Marine Bacterial α-Galactosidase.

Larissa Balabanova,Irina Bakunina,Lubov Slepchenko,Daria Cheraneva,Liudmila Tekutyeva,Oksana Son,Yuri Shkryl,Olga Nedashkovskaya,Anna Podvolotskaya

doi:10.3390/ijms21207666

Abstract

The biofilm-producing strains of P. aeruginosa colonize various surfaces, including food products and industry equipment that can cause serious human and animal health problems. The biofilms enable microorganisms to evolve the resistance to antibiotics and disinfectants. Analysis of the P. aeruginosa strain (serotype O6, sequence type 2502), isolated from an environment of meat processing (PAEM) during a ready-to-cook product storage (−20 °C), showed both the mosaic similarity and differences between free-living and clinical strains by their coding DNA sequences. Therefore, a cold shock protein (CspA) has been suggested for consideration of the evolution probability of the cold-adapted P. aeruginosa strains. In addition, the study of the action of cold-active enzymes from marine bacteria against the food-derived pathogen could contribute to the methods for controlling P. aeruginosa biofilms. The genes responsible for bacterial biofilm regulation are predominantly controlled by quorum sensing, and they directly or indirectly participate in the synthesis of extracellular polysaccharides, which are the main element of the intercellular matrix. The levels of expression for 14 biofilm-associated genes of the food-derived P. aeruginosa strain PAEM in the presence of different concentrations of the glycoside hydrolase of family 36, α-galactosidase α-PsGal, from the marine bacterium Pseudoalteromonas sp. KMM 701 were determined. The real-time PCR data clustered these genes into five groups according to the pattern of positive or negative regulation of their expression in response to the action of α-galactosidase. The results revealed a dose-dependent mechanism of the enzymatic effect on the PAEM biofilm synthesis and dispersal genes.

Highlights

With the growth of antibiotic resistance of pathogens, metabolites of marine bacteria with antimicrobial activity are of great interest for creating new approaches to combat them, because they may affect unknown metabolic pathways in the bacterial competitors [1,2]
The P. aeruginosa PAEM genome (6.4 Mb) has a G+C content of 66.4%, and the assemblies contain 6185 (207 contigs with protein-encoding genes, PEG), and 5864 (36 contigs with PEG of more than 500 bp) potential coding sequences (CDSs) with the bacterial core genes coverage 98.9% according to the RAST and EzBiocloud annotations, respectively (Figure 1, Table S1)
The highest similarity of the PAEM whole genome is with the epidemic strain LESB58 (96.6%), comparative genomics showed that its closest homologues are the soil microorganisms associated with agricultural crops, such as the strains M18 (95.5%) and F7696 (95, 4%)

Summary

Introduction

With the growth of antibiotic resistance of pathogens, metabolites of marine bacteria with antimicrobial activity are of great interest for creating new approaches to combat them, because they may affect unknown metabolic pathways in the bacterial competitors [1,2]. When the concentration of signaling molecules reaches a threshold level, they activate cellular processes, which, as a rule, affect the expression of genes in the entire population. The second messenger, intracellular signaling molecule of cyclic diguanylate monophosphate (c-di-GMP), is responsible for the synthesis of the extracellular matrix’s polysaccharides and proteins as the main metabolites for biofilm formation, as well as flagellum-dependent motility [10,11]. In P. aeruginosa, c-di-GMP stimulates the synthesis of two different extracellular polysaccharides Pel and Psl with multiple pathways of transcriptional control for the transition from the free-living bacteria to their sessile forms, i.e., formation of the biofilms with emphasizing the importance of Psl as a surface attachment determinant [12]. It is known that c-di-GMP can bind to various classes of proteins that differ in structure and amino acid sequences [16,17,19]

Methods

Results

Conclusion