Influence of climatic variation on microbial communities during organic Pinot noir wine production

Abstract

To assess the possible impact of climatic variation on microbial community composition in organic winemaking, we employed a metabarcoding approach to scrutinize the microbiome in a commercial, organic, Pinot noir wine production system that utilizes autochthonous fermentation. We assessed microbial composition across two vintages (2018 and 2021) using biological replicates co-located at the same winery. Microbial dynamics were monitored over four important fermentation time points and correlated with contemporaneous climate data. Bacterial (RANOSIM = 0.4743, p = 0.0001) and fungal (RANOSIM = 0.4738, p = 0.0001) compositions were different in both vintages. For bacteria, Lactococcus dominated the diversity associated with the 2018 vintage, while Tatumella dominated the 2021 vintage. For fungal populations, while Saccharomyces were abundant in both vintages, key differences included Starmerella, copious in the 2018 vintage; and Metschnikowia, substantive in the 2021 vintage. Ordination plots correlated the climatic variables with microbial population differences, indicating temperature as a particularly important influence; humidity values also differed significantly between these vintages. Our data illustrates how climatic conditions may influence microbial diversity during winemaking, and further highlights the effect climate change could have on wine production.

Fig 1

Relative abundance of bacterial genera in (A) 2018 vintage replicate A; (B) 2018 vintage replicate B; (C) 2021 vintage replicate A; (D) 2021 vintage replicate B. Relative abundances are shown at the genus level. Bacteria which could not be resolved to the genus level are shown at the family level. Similarities between the replicates in each vintage can be observed. SW = Samples Winery; SV = Samples Vineyard.

Fig 2

Bacterial alpha diversity (Shannon diversity index) of the ferment samples from (A) Replicate A; (B) Replicate B. The 2018 vintage displayed a higher diversity compared to the 2021 vintage. A similar conclusion can be drawn from both replicates.

Fig 3

Relative abundance of Fungal genera in (A) 2018 vintage replicate A; (B) 2018 vintage replicate B; (C) 2021 vintage replicate A; (D) 2021 vintage replicate B. Relative abundances are shown at the genus level. Replicates in each vintage bear close resemblance. SW = Samples Winery; SV = Samples Vineyard.

Fig 4

NMDS ordination for (A) Bacterial ASVs (B) Fungal ASVs associated with vintage 2018 and 2021 ferments. Fitting with environmental variables shows Maximum temperature (Max_Te) as the major factor influencing the 2021 vintage (blue) and the other climatic variables i.e Minimum temperature (Min. Te), Average temperature (Ave. Te), Minimum relative humidity (Min.RH), Average relative humidity (Ave. RH), Maximum relative humidity (Mx. RH), and rain, all correlating (S3 File) and having an impact on the 2018 community (purple). Red points depict the amplicon sequence variants (ASVs). Ellipses shown represent 95% confidence intervals.