The Streptomyces antibiotic regulatory protein (SARP) family regulators have been shown to control the production of secondary metabolites in many Streptomyces species as the most downstream regulators in the regulatory cascade. Streptomyces lavendulae FRI-5 produces a blue pigment (indigoidine) together with two types of antibiotics: D-cycloserine and the nucleoside antibiotics. The production of these secondary metabolites is governed by a signaling system consisting of a γ-butyrolactone, IM-2 [(2R,3R,1'R)-2-1'-hydroxybutyl-3-hydroxymethyl-γ-butanolide], and its cognate receptor, FarA. Here, we characterized two regulatory genes of the SARP family, farR3 and farR4, which are tandemly located in the proximal region of farA. farR3 is transcribed both as a monocistronic RNA and as a bicistronic farR4-farR3 mRNA, and the expression profile is tightly controlled by the IM-2/FarA system. Loss of farR3 delayed and decreased the production of indigoidine without any changes in the transcriptional profile of other far regulatory genes, indicating that FarR3 positively controls the biosynthesis of indigoidine and is positioned in the downstream region of the IM-2/FarA signaling system. Meanwhile, loss of farR4 induced the early production of IM-2 by increasing transcription of an IM-2 biosynthetic gene, farX, indicating that FarR4 negatively controls the biosynthesis of IM-2. Thus, our results suggested differential contributions of the SARP family regulators to the regulation of secondary metabolism in S. lavendulae FRI-5. This is the first report to show that an SARP family regulator is involved in the biosynthesis of a signaling molecule functioning at the most upstream region of the regulatory cascade for Streptomyces secondary metabolism.

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In breweries, rapid and accurate identification of unknown microbial contaminants and the associated risk assessment of beer spoilage are of critical importance to ensure proper corrective measures are taken. In this context, the nanopore based sequencer, MinION, developed by Oxford Nanopore Technologies, is of particular interest. MinION is a low cost, portable, real time device for DNA and RNA sequencing. Recently, our group developed and evaluated a MinION sequencer based microbial identification platform for beer spoilage bacteria. In this study, it is used to identify yeast strains. The nuclear ribosomal RNA genes and their internal transcribed spacer regions from a wide variety of beer spoilage yeasts, commonly found in the brewery environment, were sequenced using two different sequencing kits ‐ Ligation Sequencing Kit and Rapid Barcoding Kit ‐ and analysed using consensus sequence‐based approach. Comparative evaluation of Sanger sequencing and MinION sequencing was performed to evaluate the performance of the MinION platform in the identification of yeasts. Our methods successfully identified yeasts at the species level rapidly (approximately 3.5 hours from DNA extraction to data analysis), and with high accuracy that is comparable to Sanger sequencing (average percentage identity >98.9%). The MinION sequencer based microbial identification platform, equipped for both bacterial and yeast identification, is a powerful tool for on‐field rapid and accurate identification of beer spoilage and brewery related microorganisms. This new identification approach will potentially revolutionise the way microbial identification is performed in brewery quality control and assurance laboratories. © 2021 The Institute of Brewing & Distilling