World Journal of Microbiology and Biotechnology ( IF 4.0 ) Pub Date : 2021-08-18 , DOI: 10.1007/s11274-021-03121-3 Katharina M. Hermann 1, 2 , Anant V. Patel 1 , Alexander Grünberger 2
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The control of root-feeding wireworms has become more challenging as synthetic soil insecticides have been progressively phased out due to environmental risk concerns. Innovative microbial control alternatives such as the so-called attract-and-kill strategy depend on the rapid and successful development of dried encapsulated microorganisms, which is initiated by rehydration. Casein is a functional additive that is already used in food or pharmaceutical industry due to its water binding capacity. Cross-linked forms such as formalin-casein (FC), exhibit altered network structures. To determine whether FC influences the rehydration of alginate beads in order to increase the efficacy of an attract-and-kill formulation for wireworm pest control, we incorporated either casein or FC in different alginate/starch formulations. We investigated the porous properties of alginate/starch beads and subsequently evaluated the activities of the encapsulated entomopathogenic fungus Metarhizium brunneum and the CO2 producing yeast Saccharomyces cerevisiae. Adding caseins altered the porous structure of beads. FC decreased the bead density from (1.0197 ± 0.0008) g/mL to (1.0144 ± 0.0008) g/mL and the pore diameter by 31%. In contrast to casein, FC enhanced the water absorbency of alginate/starch beads by 40%. Furthermore, incorporating FC quadrupled the spore density on beads containing M. brunneum and S. cerevisiae, and simultaneous venting increased the spore density even by a factor of 18. Moreover, FC increased the total CO2 produced by M. brunneum and S. cerevisiae by 29%. Thus, our findings suggest that rehydration is enhanced by larger capillaries, resulting in an increased water absorption capacity. Our data further suggest that gas exchange is improved by FC. Therefore, our results indicate that FC enhances the fungal activity of both fungi M. brunneum and S. cerevisiae, presumably leading to an enhanced attract-and-kill efficacy for pest control.
Graphic abstract
中文翻译：
福尔马林-酪蛋白增强海藻酸钙珠的吸水性和封装的绿僵菌和酿酒酵母的活性
由于环境风险问题，合成土壤杀虫剂已被逐步淘汰，因此控制食根线虫变得更具挑战性。创新的微生物控制替代方案，例如所谓的吸引和杀死策略，取决于干燥包封微生物的快速和成功开发，这是通过再水化启动的。酪蛋白是一种功能性添加剂，由于其水结合能力，已被用于食品或制药行业。交联形式，如福尔马林-酪蛋白 (FC)，表现出改变的网络结构。为了确定 FC 是否影响藻酸盐珠的再水化，以提高吸引和杀死线虫害虫防治配方的功效，我们在不同的藻酸盐/淀粉配方中加入了酪蛋白或 FC。绿僵菌和产生CO 2 的酵母酿酒酵母。添加酪蛋白改变了珠子的多孔结构。FC 将珠密度从 (1.0197 ± 0.0008) g/mL 降低到 (1.0144 ± 0.0008) g/mL，孔径降低了 31%。与酪蛋白相比，FC 将藻酸盐/淀粉珠的吸水率提高了 40%。此外，加入 FC 使含有M. brunneum和S. cerevisiae 的珠子上的孢子密度增加了四倍，同时排气使孢子密度增加了 18 倍。此外，FC 增加了M. brunneum和S. cerevisiae产生的CO 2总量29%。因此，我们的研究结果表明，较大的毛细血管可增强再水化，从而提高吸水能力。我们的数据进一步表明，FC 改善了气体交换。因此，我们的结果表明，FC 增强了真菌M. brunneum和S. cerevisiae的真菌活性，可能导致害虫控制的诱杀功效增强。
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