March 2020 | Vol. 48 | No. 1 Microbiol. Biotechnol. Lett. (2020), 48(1), 12–23 http://dx.doi.org/10.4014/mbl.1909.09016 pISSN 1598-642X eISSN 2234-7305 Microbiology and Biotechnology Letters Enhancement of β-cyclodextrin Production and Fabrication of Edible Antimicrobial Films Incorporated with Clove Essential Oil/β-cyclodextrin Inclusion Complex Mohamed G. Farahat* Botany and Microbiology Department, Faculty of Science, Cairo University, 12613 Giza, Egypt Received: October 1, 2019 / Revised: November 24, 2019 / Accepted: November 26, 2019 Introduction Microbial contamination of food products accelerates the deterioration process and increases the risk of food- borne illness caused by potentially life-threatening pathogens. Ordinarily, food contamination originates superficially therefore, proper surface treatment and packaging is crucial for assuring food quality and safety [1]. Recently, edible films have gained much interest in preserving various food products, retaining their firmness and restricting weight loss that occurs due to loss of moisture [2-4]. Chitosan is an abundantly available biodegradable polysaccharide that demon- strates remarkable film-forming properties [5-7]. Furthermore, the edible films could be used as a vehicle for additives such as antioxidants and antimicrobials, Edible films containing antimicrobial agents can be used as safe alternatives to preserve food products. Essential oils are well-recognized antimicrobials. However, their low water solubility, volatility and high sensitivity to oxygen and light limit their application in food preservation. These limitations could be overcome by embedding these essential oils in complexed product matrices exploiting the encapsulation efficiency of β-cyclodextrin. This study focused on the maximization of β-cyclodextrin production using cyclodextrin glucanotransferase (CGTase) and the evaluation of its encapsulation efficacy to fabricate edible antimicrobial films. Response surface methodology (RSM) was used to optimize CGTase production by Brevibacillus brevis AMI-2 isolated from mangrove sediments. This enzyme was partially purified using a starch adsorption method and entrapped in calcium alginate. Cyclodextrin produced by the immobilized enzyme was then confirmed using high performance thin layer chromatography, and its encapsulation effi- ciency was investigated. The clove oil/β-cyclodextrin inclusion complexes were prepared using the co- precipitation method, and incorporated into chitosan films, and subjected to antimicrobial testing. Results revealed that β-cyclodextrin was produced as a major product of the enzymatic reaction. In addition, the incorporation of clove oil/β-cyclodextrin inclusion complexes significantly increased the antimicrobial activity of chitosan films against Staphylococcus aureus, Staphylococcus epidermidis, Salmonella Typhimurium, Escherichia coli, and Candida albicans. In conclusion, B. brevis AMI-2 is a promising source for CGTase to synthesize β-cyclodextrin with considerable encapsulation efficiency. Further, the obtained results suggest that chitosan films containing clove oils encapsulated in β-cyclodextrin could serve as edi- ble antimicrobial food-packaging materials to combat microbial contamination. Keywords: β-cyclodextrin glucanotransferase, Brevibacillus, RSM, optimization, immobilization *Corresponding author Tel: +20-1116080701, Fax: +20-235727556 E-mail: farahat@cu.edu.eg © 2020, The Korean Society for Microbiology and Biotechnology