Fermentation Optimization, Fungistatic Effects and Tomato Growth Promotion of Four Biocontrol Bacterial Strains

Yao Zhang,Jiayin Liu,Sibo Liang,Xingyuan Wang,Yuying Shi,Aoxue Wang,Xiuling Chen

doi:10.3390/agriculture11070686

Abstract

Tomato is a widely cultivated crop that is important for its nutritional value and genetic diversity. Tomato production is seriously challenged by pests and diseases, among which tomato gray mold and leaf mold are particularly serious. Biological control is one of the most preferred methods for disease management in tomato production. At present, the fungi used to control tomato gray mold are mainly Trichoderma and yeast. Bacillus and actinomycetes are the most effective microorganisms for controlling tomato leaf mold. Tomato gray mold and leaf mold often occur at the same time during the production process, yet there are fewer strains for controlling both diseases at the same time. Biocontrol bacteria Pseudomonas azotoformans WXCDD51, Bacillus sp. WXCDD105, Bacillus subtilis BS and Bacillus amyloliquefaciens BS WY-1, which were isolated and screened in the previous stage, can prevent both tomato gray mold and leaf mold. Here, we optimized liquid fermentation for the four biocontrol bacterial strains together. We obtained the best fermentation medium formula and fermentation conditions for the four biocontrol bacteria. The broad-spectrum properties of the four biocontrol bacteria were tested, and, on this basis, compound strains were constructed. The control effect of single and compound strains on tomato gray mold and leaf mold was evaluated. Their potential effects on the growth of tomato seeds and seedlings were also studied. This research provides a foundation for the development and use of compound bacteria for growth promotion and disease management in tomato production.

Highlights

Gray mold and leaf mold are prevalent in tomato production, leading to huge economic losses [1,2,3]
The strain WXCDD105 was previously identified as Bacillus subtilis suBap.subtilis (Figures S1 and S2)
The end of logarithmic growth was at 18–30 h; 18 h was selected as this the best inoculation age, while the bacteria count reached a maximum at 48 h (Figure S3)

Summary

Introduction

Gray mold and leaf mold are prevalent in tomato production, leading to huge economic losses [1,2,3]. They were originally controlled with chemical pesticides; this control method is not sustainable due to the high cost of synthetic pesticides and their long-term effect on the environment. Botrytis cinerea (teleomorph: Botryotinia fuckeliana) is an airborne plant pathogen with a necrotrophic lifestyle, attacking over 200 crop hosts worldwide [4]. It causes the gray mold disease in tomato and can damage many parts of the crop plant, leading to identifiable symptoms. Low temperature and high humidity, weak host growth, low ventilation, high planting density, continuous rainy weather and repeated cropping are all likely to induce these two diseases [8]

Methods

Results

Discussion

Conclusion