The discovery of antibiotics and pesticides has greatly contributed to the social and economic development of human society but, due to the long-term irrational application, it has led to drug-resistant microorganisms, environmental damage, and other hazards, so the selection of alternative natural, safe, and non-hazardous bioactive substances is an effective solution for this problem. D-limonene is a bioactive compound widely present in various plant essential oils, exhibiting excellent broad-spectrum bioactivity and promising prospects for development and clinical application. This review provides a detailed overview of the biological activities of D-limonene, emphasizing its antimicrobial, anthelmintic, insecticidal, and medicinal potential. While nanoencapsulation technology shows promise in improving the physicochemical properties of D-limonene and enhancing its practical applications, it is also crucial to comprehensively evaluate the potential side effects of D-limonene before use.

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.

This research utilized Jintang navel oranges as the primary raw material, and employed two distinct yeast strains, Saccharomyces cerevisiae SC-125 and Angel yeast SY, for a dual fermentation approach. Employing single-strain fermentation as the control, this study aims to ascertain the physicochemical markers, alterations in organic acids and amino acids, alongside the antioxidant properties throughout the fermentation process, all within an optimized environment. The characterization of flavor compounds in the navel orange wines subjected to diverse yeast strains and mixed fermentation was conducted using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HP-SPME/GC-MS). This method facilitated the identification of flavor compound types and concentrations. Moreover, electronic sensory systems including electronic noses and electronic eyes were harnessed to discern distinctions among various navel orange wines. Through these techniques, the research aimed to elucidate the variances induced by different yeast strains during both individual and mixed fermentation processes, shedding light on their impacts on the ultimate quality of navel orange wines.

Pellicle formation is the most typical characteristic of deteriorating fermented vegetable products. Perilla frutescens essential oil (PEO) is widely used as a useful natural preservative. However, few studies have addressed the antifungal activity and mechanism of PEO in pellicle formation microorganisms, and it is still unclear whether it can inhibit pellicle formation and affect its volatile compounds in Sichuan pickles. The current study showed that PEO can inhibit pellicle formation during fermentation of Sichuan pickles as it had significant antifungal activity against the pellicle formation microorganisms Candida tropicalis SH1 and Pichia kluyveri SH2. The minimum inhibitory concentration (MIC) of PEO against C. tropicalis SH1 and P. kluyveri SH2 was determined to be 0.4 μL/mL, and the minimum fungicidal concentrations (MFCs) were 1.6 μL/mL and 0.8 μL/mL, respectively. The antifungal mechanism was activated as a result of damage to the cell membrane, an increase in the cell permeability, a decrease in the mitochondrial membrane potential, and the inhibition of ATPase activity. Meanwhile, the addition of PEO to Sichuan pickles can enrich the profiles of volatile compounds during fermentation, including limonene, myrcene, 1,8-cineole, linalool, perilla ketone, heptanal, hexanal, α-thujone and β-terpineol and thus improve the overall sensory acceptability. These results indicated that PEO has the potential to be used as a novel food preservative to control pellicle formation in fermented vegetables.

The Pichia kluyveri, a proliferation commonly found in Sichuan pickles (SCPs), can accelerate the growth and reproduction of spoilage bacteria, causing off-odor development and decay. Although D-limonene, a common natural preservative, effectively restricts P. kluyveri, its inhibitory mechanism remains unclear. This study aimed to elucidate this molecular mechanism by investigating the impact on basic P. kluyveri metabolism. The findings revealed that D-limonene inhibited P. kluyveri growth and disrupted the transcription of the genes responsible for encoding the enzymes involved in cell wall and membrane synthesis, oxidative phosphorylation, glycolysis, and the tricarboxylic acid (TCA) cycle pathway. The results indicated that these events disrupted crucial metabolism such as cell wall and membrane integrity, adenosine triphosphate (ATP) synthesis, and reactive oxygen species (ROS) balance. These insights provided a comprehensive understanding of the inhibitory effect of D-limonene on the growth and reproduction of P. kluyveri while highlighting its potential application in the SCP industry.

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.