Strain-specific polyketide synthase genes of Aspergillus niger

• Published in: International journal of food microbiology 2012-04, Vol.155 (3), p.137-145
• Main Authors: Ferracin, Lara Munique, Fier, Carla Beatriz, Vieira, Maria Lucia Carneiro, Monteiro-Vitorello, Claudia Barros, Varani, Alessandro de Mello, Rossi, Maria Magdalena, Müller-Santos, Marcelo, Taniwaki, Marta Hiromi, Thie Iamanaka, Beatriz, Fungaro, Maria Helena Pelegrinelli
• Format: Article
• Language: English
• Subjects: Aspergillus niger; Aspergillus niger - enzymology; Aspergillus niger - genetics; Bioinformatics; Computational Biology; Data processing; DNA, Fungal - genetics; Genes, Fungal; Genetic Variation; Genomes; Multigene Family; Mycotoxin; Nucleotide sequence; Nucleotides; Ochratoxin; Ochratoxins - biosynthesis; Polyketide synthase; Polyketide Synthases - genetics; Polymerase chain reaction; Secondary metabolites; Sequence Analysis, DNA; Species Specificity; Strain-specific polyketide synthase
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2012.01.020

In silico comparison of 34 putative pks genes in Aspergillus niger strain CBS 513.88 versus A. niger strain ATCC 1015 genome revealed significant nucleotide identity (>95% covering a minimum of 99% of the gene sequence) for 31 of these genes (approximately 91%). A. niger CBS 513.88 harbors three putative pks genes (An01g01130, An11g05940, and An15g07920), for which nucleotide identity was not found in A. niger ATCC 1015. To compare the results of the in silico analysis with the in vivo situation, experimental data were obtained for a large number of A. niger strains obtained from different substrates and geographical regions. Three putative pks genes that were found to be variable between the two A. niger strains using bioinformatics tools were in fact strain-specific genes based on experimental data. The PCR amplification signals for the An01g01130, An11g05940, and An15g07920 pks genes were detected in only 97%, 71%, and 26% of the strains, respectively. Southern blot analyses confirmed the PCR data. Because one of the strain-specific pks genes (An15g07920) is located in a putative ochratoxin cluster, we focused our investigation on that region. We assessed the ochratoxin production capability of the 119 A. niger strains and found a positive association between the presence of this pks gene and the capability of the respective strain to produce ochratoxin. ► In silico analyses were performed to the pks gene inventory of two A. niger genomes. ► A. niger CBS 513.88 harbors three pks genes that are not in A. niger ATCC 1015. ► We compare the results of the in silico analyses with the in vivo situation. ► An association between the An15g07920 pks gene and ochratoxin production was found.