N Bacha1, Z Echarki, F Mathieu, A Lebrihi. 1. Center of Biotechnology and Microbiology, University of Peshawar, Khyber Pakhtunkhwa, Pakistan; Laboratoire de Génie Chimique, INPT-UPS, Université de Toulouse, Castanet-Tolosan Cedex, France.
Abstract
AIMS: To provide an efficient technique for monitoring the off-flavoured fungal compound geosmin. METHODS AND RESULTS: Geosmin-associated gpe1 gene of Penicillium expansum displayed ≥99% similarity to cytochrome P450 gene of geosmin-producing P. restrictum, but ≤40% similarities to geosmin biosynthesis, non-cytochromic gene of Streptomyces avermitilis and cytochrome P450 genes of non-geosmin-producing Neotyphodium lolii, Phoma betae and P. paxilli. Serial 10-fold dilutions of P. expansum's DNA was subjected to a previously reported qPCR assay (Atoui et al. 2007), utilizing gpe1 specific primer pair 'SNgpe1F/SNgpe1R'. A linear relationship between DNA quantity and Cycle Threshold (Ct ), with strong correlative coefficient, was observed. Using the available physico-chemical method, geosmin was quantified in 188 grape samples. Penicillium spp's DNA was quantified in these samples, utilizing the developed qPCR assay. A strong positive correlation (R(2) = 0·97) between Penicillium's DNA and geosmin concentration was observed. Furthermore, <50 ng μl(-1) Penicillium's DNA corresponds to geosmin level below the permitted intensity limit i.e. 4, for 'Flavour Profile Analysis'. CONCLUSIONS: Penicillium spp., genomic DNA level can provide an efficient way to quantify geosmin. SIGNIFICANCE AND IMPACT OF THE STUDY: This particular qPCR technique can be utilized in numerous food industries, for the timely detection and monitoring of geosmin contamination.
AIMS: To provide an efficient technique for monitoring the off-flavoured fungal compound geosmin. METHODS AND RESULTS: Geosmin-associated gpe1 gene of Penicillium expansum displayed ≥99% similarity to cytochrome P450 gene of geosmin-producing P. restrictum, but ≤40% similarities to geosmin biosynthesis, non-cytochromic gene of Streptomyces avermitilis and cytochrome P450 genes of non-geosmin-producing Neotyphodium lolii, Phoma betae and P. paxilli. Serial 10-fold dilutions of P. expansum's DNA was subjected to a previously reported qPCR assay (Atoui et al. 2007), utilizing gpe1 specific primer pair 'SNgpe1F/SNgpe1R'. A linear relationship between DNA quantity and Cycle Threshold (Ct ), with strong correlative coefficient, was observed. Using the available physico-chemical method, geosmin was quantified in 188 grape samples. Penicillium spp's DNA was quantified in these samples, utilizing the developed qPCR assay. A strong positive correlation (R(2) = 0·97) between Penicillium's DNA and geosmin concentration was observed. Furthermore, <50 ng μl(-1) Penicillium's DNA corresponds to geosmin level below the permitted intensity limit i.e. 4, for 'Flavour Profile Analysis'. CONCLUSIONS: Penicillium spp., genomic DNA level can provide an efficient way to quantify geosmin. SIGNIFICANCE AND IMPACT OF THE STUDY: This particular qPCR technique can be utilized in numerous food industries, for the timely detection and monitoring of geosmin contamination.
Authors: Mie B Lukassen; Nadieh de Jonge; Sabine M Bjerregaard; Raju Podduturi; Niels O G Jørgensen; Mikael A Petersen; Gianmarco S David; Reinaldo J da Silva; Jeppe L Nielsen Journal: Front Microbiol Date: 2019-10-31 Impact factor: 5.640