An Introduction of Techniques to Aid in Building Microbial-Containing Formulations: From the Selection of Components to Foliage Application

摘要

The spectrum of the complexity of microbes (fungi, bacteria, viruses) as a biocontrol agent is much higher than that of the traditional chemical compounds used as an active ingredient (Al) in pesticide formulations. To develop an effective formulation using biologicals as an Al, one should consider both the physicochemical characteristics of the other components used to make up the formulation as well as the biological properties of the microbes themselves. Interface adsorption, ionic strength, ultraviolet (UV) light, radiation, residual moisture, shear forces, temperature, and the choice of surfactants are among the pivotal causes of the instability of microorganisms that one can overcome by designing a robust formulation. For microbial-containing formulations, it is also vital that the biocontrol agent both remain inactive during storage and become stimulated to its active form once applied in the environment. Furthermore, the biocontrol agent must also remain viable long enough for its mode of action to be expressed once applied in the field. In this paper, we review the main constraints, strategies to overcome them, and usual methodologies applied to the development of a successful formulation containing fungi and bacteria. In addition, we discuss methods for screening microbial adhesion to solid surfaces and monitoring the microbial cellular function in the presence of surfactants and other molecules, as well as a method for determining the formulation's ability to mitigate UV damage to the microbes. Last, we propose a new methodology to quantify microbes on leaves, which aid in the screening of formulations prior to greenhouse and field trials. Methods and cautions are presented based on case studies encompassing the development of two different formulations: (i) a water-dispersible granule formulation using Trichoderma (fungus) as the Al and (ⅱ) a suspension concentrate formulation using Bacillus (bacteria). The methodologies applied here may be useful as a basic guide for the development of microbial-containing formulations.