Effects of Alginate-Encapsulation on Bacterial Cell Viability

David Hong-Sheng, Wee (2025) Effects of Alginate-Encapsulation on Bacterial Cell Viability. Masters thesis, UNIMAS.

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Abstract

Alginate-encapsulation of bacterial cells is a type of cell immobilisation technique used in various biotechnology fields due to its numerous benefits. One of the cited benefits is the increased preservation of bacterial cell viability post-encapsulation. However, the process of encapsulation itself may inherently negatively affect cell viability. This thesis aims to study changes in cell viability after subjecting Escherichia coli BL21 DE3 cells to alginate-encapsulation. Cell viability of free cells were compared with cells that have undergone alginate-encapsulation by analysis using resazurin microtitre assay (REMA) and viability-PCR (vPCR). To reliably assess the viability of the encapsulated cells, a decapsulation step was designed and it was found that the optimal decapsulation conditions determined involved incubating encapsulated cells at 37 °C for 2 hours in PBS containing 55 mM sodium citrate and 500 ug/mL alginate lyase. To ensure REMA and vPCR were performing optimally, heat-killed cells were prepared by heating at 75 °C to preserve DNA integrity, and DNA extracts were treated with 10 ug/uL RNAse A to eliminate interference by RNA during DNA quantification. Overall, it was found that cell viability decreased following cell encapsulation with both REMA and vPCR showing a mean reduction of 14.43% and 31.54% respectively. These results could have important implications in applications whereby cell viability is of utmost importance. Our study is also the first, to our current knowledge, to employ vPCR in encapsulated cells and our workflow may serve as a reference for other relevant ongoing studies. Further research should be conducted to elucidate the relationship between encapsulated cell viability with more practical endpoints.

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