Kombucha fungus bio-coating for improving mechanical and antibacterial properties of cellulose composites

Abstract

Some microorganisms can produce biofilm to create survival conditions. These biofilms are highly resistant to different environmental conditions, and dealing with them is challenging. However, it significantly increases bacterial resistance. Hence, most relevant articles focus on destroying and preventing microorganisms' biofilm creation, and very few articles have been written on the use of microorganism biofilm for manufacturing (especially biocomposite manufacturing). Also, biofilm production by microorganisms on the intended surface (bio-coating process) is challenging. This study planned the conditions so kombucha fungus produces biofilm on a cellulose layer (bio-coating on the surface). As a result of this action, Kombucha biofilm created a biocomposite with good barrier properties and mechanical properties (tensile index: 59 k Nm/kg, burst index: 4.8 kPa.m2/g, air permeability: 189 ml/min, porosity percentage: %10, density: 0.85 gr/cm3, contact angle:72°)The composite has such strong antibacterial properties that a significant inhibition zone was formed in the well diffusion test, and a semi-inhibition zone was also observed. This inhibition zone for the Gram-positive pathogen (S. aureus) was 10.2 mm, close to the tetracycline control sample (11 mm). (the other antibacterial test results for S. aureus: MIC:15 µl, MBC:25 µl,R-number:8,and for E.coli MIC: 15 µl, MBC:25 µl, R-number7: inhibition zone:7.4 mm) These results, along with the results of the permeability and mechanical tests, further demonstrate the operational success of this surface modification. Also, due to its properties, this biocomposite can be suggested for use in wound dressing, pharmaceutical coating, and protecting food with high nutritional value and perishability.