The fungal community in Qu plays a key role in the formation of turbid rice wine (TRW) style. The Sichuan Basin and its surrounding areas have become one of the main TRW production regions in China; however, the fungal community in Qu and how they affect the characteristics of TRW remain unknown. Therefore, this study provided insight into the fungal biomarkers in Qu from Guang’an (GQ), Dazhou (DQ), Aba (AQ), and Liangshan (LQ), as well as their relationships with compounds in TRW. The main biomarkers in GQ were Rhizopus arrhizus, Candida glabrata, Rhizomucor pusillus, Thermomyces lanuginosus and Wallemia sebi. However, they changed to Saccharomycopsis fibuligera and Mucor indicus in DQ, Lichtheimia ramose in AQ, and Rhizopus microsporus and Saccharomyces cerevisiae in LQ. As a response to fungal biomarkers, the reducing sugar, ethanol, organic acids, and volatile compounds were also changed markedly in TRWs. Among important volatile compounds (VIP > 1.00), phenethyl alcohol (14.1–29.4%) was dominant in TRWs. Meanwhile, 3-methyl-1-butanol (20.6–56.5%) was dominant in all TRWs except that fermented by GQ (GW). Acetic acid (29.4%) and ethyl palmitate (10.1%) were dominant in GW and LW, respectively. Moreover, GQ biomarkers were positively correlated with acetic acid and all unique important volatile compounds in GW. DQ biomarkers had positive correlations with unique compounds of acetoin and ethyl 5-chloro-1,3,4-thiadiazole-2-carboxylate in DW. Meanwhile, the AQ biomarkers were positively correlated with all AW unique, important, and volatile compounds. Although there were not any unique volatile compounds in LW, 16 important volatile compounds in LW were positively related to LQ biomarkers. Obviously, biomarkers in different geographic Qu played vital roles in the formation of important volatile compounds, which could contribute specific flavor to TRWs. This study provided a scientific understanding for future efforts to promote the excellent characteristics of TRW by regulating beneficial fungal communities.

Phytohormones have the potential to enhance the nutrient removal efficiency of aquatic plants in wastewater treatment. Here, we investigated the impact of indoleacetic acid (IAA) on nitrogen removal by Hydrocotyle vulgaris Lam during the remediation process of eutrophic water. This investigation involved evaluating the biological indicators of H. vulgaris Lam, the nitrogen salt removal efficiency in eutrophic water, as well as analyzing the bacterial structure and function in both the rhizosphere and eutrophic water surrounding H. vulgaris Lam. The results indicated that surface-sprayed 50 mg/L IAA significantly stimulated the growth of H. vulgaris Lam, including parameters such as blade number, leaf area, petiole length, stem thickness, stem length, and root length of H. vulgaris Lam. Furthermore, exogenous application of IAA significantly accelerated the nitrogen removal of NH₄⁺−N, NO₃⁻−N and total nitrogen (TN) in eutrophic water by promoting the NH₄−N uptake of H. vulgaris Lam and NO₃⁻−N denitrification. These findings suggest a potential application for exogenous IAA to enhance the nitrogen removal of H. vulgaris Lam in eutrophication control.