Cell immobilization of recombinant kluyveromyces lactis on carbon nanomaterial for the improvement of xylanase production

• Main Author: Abdul Manaf, Shoriya Aruni
• Format: Thesis
• Language: English; English; English
• Published: 2022
• Subjects: TP Chemical technology
• Online Access: http://eprints.uthm.edu.my/8486/

Xylanase is a major hydrolysis enzyme that is important for xylan degradation in applications such as paper pulping, food additive production and animal feedstocks. It is typically found in fungi with low productivity and complex processes. As a result, an alternative method for increasing xylanase production that is simple and less time-consuming is desired. The goal of this research is to produce a large-scale xylanase by immobilizing recombinant Kluyveromyces lactis with carbon nanomaterial and to apply a direct whole cell biocatalyst method for xylooligosaccharides production. Therefore, four carbon nanomaterials were screened using the pretreatment process that measured xylanase activity and cell growth. Carbon nanotubes (CNT) and graphene oxide (GO) were analyzed and their immobilization and culture condition factors were optimized using Response Surface Methodology (RSM) with different design models, as well as large-scale production process using a bioreactor. Analysis on the carbon nanomaterial was done using a Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray (FESEM-EDX) and Fourier Transform Infrared spectroscopy (FTIR) while Ultra High-Performance Liquid Chromatography (UHPLC) was used to analyze the final sugar product. The most important factors in xylanase production with low cell leakage are cell loading and agar concentration. Following RSM screening and optimization, the xylanase production from free cells (1.39 U/mL) increased tenfold after cell immobilization (10.30 U/mL), and increased to 15 U/mL during the upscale process in the bioreactor. The immobilized cells can be reused for up to 7 fermentation cycles and stored at 4 ℃ for up to 90 days. The end products of lignocellulosic biomass bioconversion are xylobiose and xylotriose. Cell immobilization with carbon nanomaterials has been shown to successfully enhance xylanase production, opening up a new path to improved bioprocessing, particularly for the production of enzymes with reusability and long-term storage.