An innovative way to treat cash crop wastes: The fermentation characteristics and functional microbial community using different substrates to produce Agricultural Jiaosu.

With the increase of global demand for cash crops, a large of cash crop waste was produced and caused severe environmental issues. To produce Agricultural Jiaosu (AJ) using these wastes is a sustainable waste disposal method. However, the fermentation mechanism, metabolites, and microbial characteristics of AJ fermented with different substrates remain unclear. In this study, the effects of different substrates (fruit and vegetable waste and Chinese herbal medicine waste) on the fermentation characteristics of AJ, including metabolites and microbial community properties, were investigated. The results revealed that AJ fermentation was a process of converting organic matter into organic acids and other metabolites, mainly including hydrolysis, acidogenesis, and maturation stages. At the genus level, Lactobacillus, Acetobacter, Hydrogenibacillus, Halomonas, and Prevotella_1 were the dominant bacteria in the fermentation system. The bacterial diversity of composite substrate AJ was higher than that of single substrate AJ. The organic acids and secondary metabolites concentration and the composition of key microorganisms depended on the substrate type. Furthermore, AJ's potential functional genes were mainly concentrated in cofactors and vitamin, carbohydrate, and amino acid metabolism. The findings of this study indicated that AJ is an innovative eco-friendly technology that can convert cash crop wastes into sustainable eco-products, and that its characteristics depend on the substrate type. Therefore, the substrate used to produce AJ should be carefully selected according to the application field.

Agricultural Jiaosu: An Eco-Friendly and Cost-Effective Control Strategy for Suppressing Fusarium Root Rot Disease in Astragalus membranaceus.

Root rot caused by the pathogenic fungi of the Fusarium genus poses a great threat to the yield and quality of medicinal plants. The application of Agricultural Jiaosu (AJ), which contains beneficial microbes and metabolites, represents a promising disease control strategy. However, the action-effect of AJ on Fusarium root rot disease remains unclear. In the present study, we evaluated the characteristics and antifungal activity of AJ fermented using waste leaves and stems of medicinal plants, and elucidated the mechanisms of AJ action by quantitative real-time PCR and redundancy analysis. The effects of AJ and antagonistic microbes isolated from it on disease suppression were further validated through a pot experiment. Our results indicate that the AJ was rich in beneficial microorganisms (Bacillus, Pseudomonas, and Lactobacillus), organic acids (acetic, formic, and butyric acids) and volatile organic compounds (alcohols and esters). It could effectively inhibit Fusarium oxysporum and the half-maximal inhibitory concentration (IC50) was 13.64%. The antifungal contribution rate of the microbial components of AJ reached 46.48%. Notably, the redundancy analysis revealed that the Bacillus and Pseudomonas genera occupied the main niche during the whole inhibition process. Moreover, the abundance of the Bacillus, Pseudomonas, and Lactobacillus genera were positively correlated with the pH-value, lactic, formic and butyric acids. The results showed that the combined effects of beneficial microbes and organic acid metabolites increased the efficacy of the AJ antifungal activity. The isolation and identification of AJ's antagonistic microbes detected 47 isolates that exhibited antagonistic activities against F. oxysporum in vitro. In particular, Bacillus subtilis and Bacillus velezensis presented the strongest antifungal activity. In the pot experiment, the application of AJ and these two Bacillus species significantly reduced the disease incidence of Fusarium root rot and promoted the growth of Astragalus. The present study provides a cost-effective method to control of Fusarium root rot disease, and establishes a whole-plant recycling pattern to promote the sustainable development of medicinal plant cultivation.

The effects of C/N (10-25) on the relationship of substrates, metabolites, and microorganisms in "inhibited steady-state" of anaerobic digestion.

The carbon/nitrogen ratio (C/N) is a key parameter that affects the performance of anaerobic digestion (AD). Recent AD research has focused on optimizing the C/N of feedstock. The so-called "inhibited steady-state" refers to a special state of ammonia inhibition of AD that often occurs at low-C/N (below 25) when degradable nitrogen-rich substrates, such as livestock manure, are used as feedstock. However, the mechanism behind the "inhibited steady-state" is still unknown. In the current study, co-digestion and recirculation were used to create a C/N gradient in the influent to explore the relationship between substrates, metabolites, and microorganisms in the "inhibited steady-state." Data were collected at the macro, microbial, and genetic levels. Three CSTRs were successfully made run into the "inhibited steady-state" using influent C/Ns of 10-12. Digestion performance levels of R10-R12 were low and stable, transitioning from an aceticlastic methane-producing pathway to a hydrogenotrophic pathway as the C/N gradually decreased. As the abundance of the hydrogenophilic methanogens increased, the abundance of syntrophic acetate-oxidizing bacteria (SAOB) also increased. The succession between populations of Methanosaeta and Methanosarcina may be used as a microbiological indicator of ammonia inhibition. Under high-C/Ns, cooperation among bacteria was high, while under low-C/Ns, competition among bacteria was high. These results clarify the processes underlying the "inhibited steady-state," which is a condition often faced in actual large-scale biogas facilities that use degradable nitrogen-rich substrates. Moreover, practical guidelines for evaluating ammonia inhibition are provided, and strategies to alleviate ammonia suppression are developed.

A microbial ecosystem: agricultural Jiaosu achieves effective and lasting antifungal activity against Botrytis cinerea.

Synthetic fungicides are eco-unfriendly to agriculture and the environment. Agricultural Jiaosu (AJ), which originates from organic wastes, has the potential to be a substitute for synthetic fungicides. In this study, the characteristics of AJ and its antifungal activity against Botrytis cinerea were investigated for the first time. AJ was rich in lactic acid (4.46 g/L), acetic acid (1.52 g/L), Lactobacillus (72.45%) and Acetobacter (15.23%), which was a microbial ecosystem consisting of acid-based substances (AS) and beneficial microorganisms (BM). The results of the antifungal assays suggested that B. cinerea was effectively inhibited by AJ, with the half-maximal inhibitory concentration (IC50) of 9.24%. AJ showed the strongest and most-lasting inhibitory effect compared to cell-free supernatant and microbial solution of AJ, indicating that AS and BM and their synergistic effect contributed to the antifungal activity of AJ. Two-step inhibition' is an antifungal mode of AJ. Firstly, AS not only inhibited the pathogen directly but also provided a dominant niche for BM of AJ. Then, BM in AJ, especially Acetobacter, proliferated and metabolized acetic acid continuously. Thus, AJ achieved high-efficiency and long-acting inhibition. AJ is a promising biological agent considering its features of an eco-friendly, low-cost and easy-to-operate biological agent in rural areas.

Accelerated biomethane production from lignocellulosic biomass: Pretreated by mixed enzymes secreted by Trichoderma viride and Aspergillus sp.

Biological pretreatment is a promising technology to increase biogas yield. The methane yield and microbial community resulting from anaerobic digestion of maize straw after pretreatment of enzymes [extracted from Trichoderma viride (ETv) and Aspergillus sp. (EAs)] at different mixing ratios [5/0, 4/1, 3/2, 2/3, 1/4, 0/5] were evaluated. The methane yields from mixed enzymes pretreatment were higher than single enzymes pretreatments of ETv and EAs. The optimal enzymes mixing ratio of ETv and EAs was found to be 2/3, with the cumulative methane yield 512.64 mL/g TSadded, which was 31.74% higher than the control. Enzymatic pretreatment promoted an increase in the abundance of bacteria and archaea associated with cellulose decomposition. The majority of bacteria and archaea were assigned to Bacteroidetes, Firmicutes and Methanosaeta.

Spiral spin order of self-assembled Co nanodisk arrays.

Spin order in hexagonal close packed cobalt nanodisk rows is quantitatively determined by off-axis electron holography. Periodic variation in the density of the local magnetic flux shows features of a spiral spin arrangement along the row axis, resulting from a tilted magnetic moment of nanoparticles with respect to the nanodisk axis.