Utilization of the sugar fraction from Arabica coffee pulp as a carbon source for bacteria producing cellulose and cytotoxicity with human keratinocyte

Abstract

Coffee pulp (CP), a by-product of coffee production, is an underutilized resource with significant potential value. CP contains monosaccharides that can serve as an ideal carbon source for bacterial cultivation, enabling the production of value-added components such as medical-grade cellulose. Herein, we extracted the sugar fraction from Arabica CP and used it as a supplement in a growing media of a bacteria cellulose (BC), Komagataeibacter nataicola. The BC was then characterized and tested for cytotoxicity. The CP sugar fraction yielded approximately 7% (w/w) and contained glucose at 4.52 mg/g extract and fructose at 7.34 mg/g extract. Supplementing the sugar fraction at different concentrations (0.1, 0.3, 0.5, 0.7, and 1 g/10 mL) in sterilized glucose yeast extract broth, the highest yield of cellulose (0.0020 g) occurred at 0.3 g/10 mL. It possessed similar physicochemical attributes to the BC using glucose, with some notable improvements in fine structure and arrangement of the functional groups. In cytotoxicity assessments on HaCaT keratinocyte cells, bacterial cellulose concentrations of 2–1000 µg/mL exhibited viability of ≥ 80%. However, higher concentrations were toxic. This research innovatively uses coffee pulp for bacterial cellulose, aligning with the principles of a bio-circular economy that focuses on sustainable biomass utilization.

RESEARCH HIGHLIGHTS

• The sugar fraction of Arabica CP (6.64 g/100 g sample) contained glucose and fructose of 4.52 and 7.34 mg/g extract respectively.

• Different sugar fraction concentrations (0.1, 0.3, 0.5, 0.7, and 1 g/10 mL) were tested in sterilized glucose yeast extract broth. Optimal BC yield (0.0020 g) was achieved at 0.3 g/10 mL.

• The BC exhibited comparable physicochemical characteristics to cellulose obtained from glucose.

• The cytotoxicity indicate that HaCaT cells exposed to 2–1000 µg/mL of BC had a percentage cell viability of ≥80%, but it was toxic at higher concentrations.

• CP represents a cheap and readily-available source for BC production, contributing to the bio-circular economic goal.

Keywords:

• Characteristic
• HaCaT cells
• komagataeibacter nataicola
• pharmaceuticals

Acknowledgments

We would like to acknowledge the student fund in the forms of scholarship and Teaching Assistant and Research Assistant (TA/RA) from Graduate School, Chiang Mai University and Southeast Asian Regional Center for Graduate Study and Research in Agriculture (Student Mobility Grant and PhD Research Scholarship) granted to Jiraporn Sangta.

Credit authorship contribution statement

Jiraporn Sangta: Methodology, Investigation, Validation, Formal analysis, Writing – original draft, Visualization. Warintorn Ruksiriwanich; Korawan Sringam; Pornchai Rachtanapun: Formal analysis. Chuda Chittasupho: Methodology & Investigation. Cassie Bakshani; William Willats: Writing – review & editing. Sarana Rose Sommano: Conceptualization, Supervision, Writing – review & editing, Project administration.

Disclosure statement

No potential conflict of the interest was reported by the author(s). The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability statement

Not applicable.

Additional information

Funding

This research project was supported by Fundamental Fund 2022 (FF65/004), Chiang Mai University.