Microbially influenced corrosion (MIC) in anaerobic environments accounts for many severe failures and losses in different industries. Sulfate-reducing bacteria (SRB) represent a typical class of corrosive microorganisms capable of acquiring electrons from steel through extracellular electron transfer processes, thereby inducing severe electrical microbially influenced corrosion (EMIC). Although prior research has underscored the significance of extracellular electron transfer, the contribution of EMIC to the whole MIC has not been comprehensively studied. In this study, Q235 steel coupons were employed in an H-shaped electrochemical cell to conduct electrochemical and coupon immersion experiments, aiming to determine the contribution of EMIC to the overall MIC. The experiments were conducted under two distinct carbon source conditions: 100% carbon source (CS) and 1% CS environments. It was observed that the biotic electrodes exhibited significantly higher cathodic currents, with the most pronounced biological cathodic activity detected in the 100% CS biotic medium. The voltammetric responses of the electrodes before and after changes in the medium confirmed the biocatalytic capability of the attached biofilm in stimulating the cathodic reaction. The proportion of EMIC in MIC was calculated using linear polarization resistance, revealing a trend over time. Additionally, weight loss tests indicated that the contribution of EMIC to the total MIC was approximately 27.69%. Furthermore, the results demonstrated that while the overall corrosion rate was lower in the 1% CS environment, the proportion of EMIC in MIC increased to approximately 37.68%.

Daqu is the core saccharifying and fermenting agent in Baijiu production and a pivotal factor in flavor formation. Challenges that often hinder traditional strong-flavor Daqu brewing include low enzymatic activity and insufficient aroma. Therefore, we have developed a novel Daqu brewing system. Furthermore, we investigated the differences in flavor profiles between traditional and novel Daqu by performing headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). We comparatively analyzed the microbial communities, metabolic functions, and flavor compositions in the two Daqu types via absolute quantitative metagenomics. Functional microorganisms were significantly enriched in the novel Daqu, which exhibited enhanced carbohydrate metabolism and a highly robust acidic environment owing to the fostering of core functional genera such as Aspergillus, Saccharomyces, and Pediococcus. This significantly increased the aldehyde and organic acid levels, which resulted in pronounced aldehydic and acidic sensory characteristics. Carbohydrate-Active EnZyme (CAZy) profiling confirmed the significantly elevated abundance of glycoside hydrolases (GHs) and glycosyltransferases (GTs) in novel Daqu, which improved starch bioconversion and synthesis of flavor precursors. Thus, this study shows that novel Daqu promotes ethanol accumulation and the synthesis of flavor compounds like acetals by strengthening the core microbiota and metabolic networks. These findings provide a theoretical foundation for enriching the aromatic complexity of Baijiu.