Development of a novel quantitative PCR assay as a measurement for the presence of geosmin-producing fungi

Nafees Bacha (1, 2) , Zerif Echarki (3) , Florence Mathieu (1) , Ahmed Lebrihi (1)

1 LGC - Laboratoire de Génie Chimique
2 UET - University of Engineering and Technology [Peshawar]
3 UdeS - Université de Sherbrooke

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 (R2 = 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’.

Mots clés: 5- Penicillium expansum; Cytochrome P450 gene; Geosmin; P. restrictum; Quantitative PCR

Domaines: Génie chimique; Génie des procédés

Nafees Bacha, Zerif Echarki, Florence Mathieu, Ahmed Lebrihi. Development of a novel quantitative PCR assay as a measurement for the presence of geosmin-producing fungi. Journal of Applied Microbiology, 2015, 118 (5), pp.1144-1151. ⟨10.1111/jam.12747⟩. ⟨hal-02134795⟩