Aims The aims of this study were to identify the structure of antibacterial lipopeptide (LP) produced by Bacillus amyloliquefaciens strain FJAT‐2349, to analyse the effects of the culture medium and temperature on LP production and to assess the biocontrol efficiency of the LPs against tomato bacterial wilt. Methods and Results Lipopeptides were extracted by acid precipitation and resolved in methanol and their structure was identified through LC‐QTOF‐MS/MS method. The antibacterial activities of the LPs were evaluated through inhibition zone experiments. The biocontrol efficiency of the LPs against tomato bacterial wilt was examined by a pot test. The LPs were composed of iturin (C₁₄–C₁₇ iturin A), fengycin (C₁₄/C₁₆ fengycin A, C₁₄ fengycin B₂, C₁₆ fengycin A₂/B₂, C₁₆–C₁₇ fengycin B, C₁₅ fengycin A derivatives and C₁₅ fengycin B derivatives) and surfactin (C₁₂–C₁₆ surfactin A). Moreover, the composition of the LPs was significantly influenced by the culture medium and temperature; the contents of iturin, fengycin and surfactin varied within the range from 0·41–5·89, 4·54–181·67 and 2·05–19·65 mg l⁻¹ in the different culture media and from 0·39–11·04, 1·45–215·14 and 7·79–24·43 mg l⁻¹ under different culture temperatures respectively. The results indicated that the contents of the LP mixture, fengycin and surfactin secreted from FJAT‐2349 all decreased along with an increasing culture temperature. The fermentation supernatants and LP extracts had the strongest inhibition activities of Ralstonia solanacearum when strain FJAT‐2349 was incubated at 25°C using potato dextrose broth as the culture medium among all the assayed culture conditions. The purified fengycin was found to be the active antibacterial compound against R. solanacearum, but the purified surfactin was not. The pot experiments demonstrated that the LPs secreted from the strain FJAT‐2349 could effectively control the tomato bacterial wilt with a biocontrol efficiency of 97·6%. Conclusions The LPs secreted from strain FJAT‐2349 could serve as potential biocontrol agents against tomato bacterial wilt. Significance and Impact of the Study The LPs exhibited good potential applications in the biocontrol of tomato bacterial wilt.

Chinese jasmine tea, a type of flower-scented tea, is produced by repeatedly mixing the base tea with the aromatic flowers of Jasminum sambac. The aim of this study was to analyze the changes in the volatiles, chemical components, and antioxidant activities of Chinese jasmine tea during six rounds of the scenting processes. The results indicated that benzyl alcohol, linalool, benzyl acetate, (Z)-3-hexenyl benzoate, methyl anthranilate, indole, and α-farnesene were seven major volatile compounds of jasmine tea. Moreover, the total amount of the volatile compounds increased gradually with increasing scenting rounds. The absorption of linalool became saturated quickly, while those of the other six major volatile compounds exhibited nearly linear increases throughout all six repeated scenting rounds. Importantly, the value of the jasmine tea flavor index, an evaluating indicator of the aroma quality, gradually increased with the progression of the repeated scenting rounds. The change of each detected taste component was less than 15% during six rounds of the scenting process. The antioxidant activities of the tea samples decreased in the first two rounds and later increased in the succeeding four rounds of the scenting process. However, the antioxidant activity of the finished tea was lower than that of the base tea, being significantly correlated with the change of catechin concentration. The findings provided insight into the changes in the volatiles, chemical components, and antioxidant activity of Chinese jasmine green tea during the repetitious scenting process, which could provide beneficial insight on improving the quality grade of the tea.

Tomato bacterial wilt (BW) caused by Ralstonia solanacearum seriously restricts tomato production and no effective control measures are available. A microbial restoration substrate (MRS) had been proved to be effective control of tomato BW in a greenhouse cultivation. In this study, MRS was combined with an avirulent Ralstonia solanacearum (aRS) strain to control the disease under an open field condition. In the two consecutive year (2017 and 2018) trials, the combined use of aRS and MRS resulted in better disease control compared with either aRS or MRS alone. Moreover, the combined treatment was more effective than expected and suggesting a synergistic control effect. Compared with control (CK, non-aRS or MRS), the application of aRS and MRS treatments alone or in combination could all promote plant growth, increase root activity and yield (e.g. the yield for the treatment of aRS + MRS increased by 463.64% in 2017). Soil nutrients, including soil organic carbon, total nitrogen, total phosphorus and total potassium contents were also significantly increased by the application of aRS and MRS treatments alone or in combination (P < 0.05). The application of MRS or in combination with aRS changed the soil from acidic to neutral, which is one of the key factors for controlling BW. The soil enzymatic activities were notably influenced by the combined use of aRS and MRS, which increased urease (87.37% in 2017 and 60.89% in 2018), catalase (93.67% in 2017 and 279.37% in 2018) and alkaline phosphatase activities (193.77% in 2017 and 455.73% in 2018). These results suggest that the combination of MRS and aRS could effectively control tomato BW and thus represents a promising new tool to control this disease.