Esikäsiteltyjen kauran kuorien vaikutus mustasotilaskärpäsen toukan kasvuun ja suolistomikrobistoon
Year: 2024
Type: dissertation
Abstract: Food industry currently produces large amounts of fibrous side-streams that are poorly utilized. This contributes to the inefficient use of raw materials in food industry, leading to increased greenhouse gas emissions and land-use. Oat hulls are a good example of a poorly utilized fibrous side-stream, as they are currently mainly burnt for energy. Black soldier fly larvae can be used to convert the fibrous side-streams of food industry back into valuable raw materials. This maintains the proteins, lipids, fats, and nutrients in the circulation, adapting the concept of circular economy. The larvae’s efficient conversion of wide variety of organic material is mainly attributed to the dynamic gut microbiota and enzymes produced by it. However, black soldier fly larvae do not utilize the fibrous side-streams efficiently unless they are pretreated. Therefore, the aim of this thesis was to improve the utilization of oat hulls by black soldier fly larvae through pretreatment by microbial fermentation. Additionally, the aim was to assess the effect of the feeding with fermented oat hulls to the gut microbiota of the larvae. Trichoderma reesei and Bacillus subtilis were used in the biological pretreatment along with frass produced by the larvae as a by-product. T. reesei and B. subtilis were expected to produce enzymes capable of degrading some of the fibers in the oat hulls, improving the feed availability for the larvae. Frass was hypothesised to improve larvae growth by providing nutritional supplement and stabilizing the microbiota of the feeding substrate. T. reesei was found to have the most notable effect on larvae growth and the composition of gut microbiota. This pretreatment method yielded significant improvements in larvae dry weight and bioconversion efficiency. Conversely, significant decrease was observed in survival rate of the larvae and diversity of the gut microbiota. The results highlight a potential trade-of between larvae growth and survivability. Bioconversion efficiency is a critical parameter considering the financial viability of black soldier fly larvae production. In this study, the positive effects outperformed the negative effects, suggesting potential for T. reesei to be used in the pretreatment of oat hulls in this context.
Source: Aaltodoc (Aalto University)
Author: Vähätaini, Saku
Language: English
Subfield: Insect Science
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7056189496