Sphenophorus levis and Helicoverpa armigera as sources of polystyrene-degrading microorganisms

• Grant number: 23/11974-8
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2024
• End date: January 31, 2026
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Flavio Henrique da Silva
• Grantee: Flavio Henrique da Silva
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated researchers: Milene Ferro ; Silvia Helena Prado Bettini

Abstract

Polystyrene is a low-cost polymer that, like other plastics, has very versatile physical and chemical properties that allow the development of a wide range of products for different applications. However, in proportion to the increasing use of this material, its accumulation in the environment is observed, leading to environmental problems. Numerous research studies have been conducted with the objective of addressing these issues, focusing on the biodegradation of this particular polymer. In this context, it has been demonstrated that specific insect larvae possess the ability to utilize polystyrene as a carbon source, and this phenomenon appears to be associated with their intestinal microbiota. This project aims to use the larvae of the coleoptera species Sphenophorus levis and the caterpillars of the lepidoptera species Helicoverpa armigera as an experimental system to investigate microorganisms and essential genes involved in the process of polymer biodegradation. The study will consist of subjecting insect larvae and caterpillars to a diet containing polystyrene and a conventional one. The objective is to compare the diversity of their intestinal microbiota with that of animals that are exclusively fed an artificial diet. Microorganisms (bacteria and filamentous fungi) will be isolated from the intestines of insects for the enrichment process in a culture medium whose only carbon source will be polystyrene. The microorganisms will be isolated and cultured on a polymer film, and the formation of biofilm and modifications to the material will be assessed. The complete sequencing of bacterial genomes will be conducted to identify the bacteria and to analyze the genes involved in the degradation process. Furthermore, alongside the investigation pertaining to bacteria, we will undertake an examination of the fungal population (comprising both unicellular and filamentous organisms) within the identical samples. The fungi will be identified by sequencing the internal transcribed spacer region (ITS), and the filamentous ones, which we will emphasize, will be isolated from solid medium plating. Furthermore, their enrichment will take place after to their growth in a culture medium supplemented with polystyrene, either as part of a mixed diet or as the sole carbon source. Following the process of isolation, fungi will be cultivated on a polystyrene film, similar to the method employed for bacteria. Subsequently, a study will be conducted to evaluate the formation of biofilm and any alterations in the material. Ultimately, the identification of individual filamentous fungi will be accomplished through sequencing the Internal Transcribed Spacer (ITS) region. In this way, we intend to characterize the intestinal fungi of the larvae of the two insects, an information still unpublished, and also verify their possible participation in the degradation of polystyrene. (AU)