Kojic acid (KA) with antibacterial activities produced by fermentation was grafted onto konjac glucomannan oligosaccharide (KGO) composed of glucose and mannose linked by β-1,4 glycosidic bonds. A novel KGO derivative, konjac glucomannan oligosaccharide kojic acid (KGOK) possessing both moisture retention and antibacterial activities was synthesized. The structure of KGOK was characterized and analyzed by thermogravimetric analysis (TG), XRD, UV-vis absorption, FTIR, and 1 H NMR. The analysis results suggest that KA was linked to the KGO molecular chain through a covalent bond, and the reaction site of KA was the methylol group. The studies demonstrate that KGOK maintained the excellent moisture absorption and retention properties of KGO and the good antibacterial activities of KA. The minimum inhibitory concentration (MIC) of KGOK is 2 mg/mL for Staphylococcus aureus, Staphylococcus epidermidis, Shewanella putrefaciens, and Salmonella enterica, while its MIC is 3 mg/mL for Escherichia coli. The multi-functionality of the KGOK synthesized from natural sources provides a theoretical foundation for their potential applications in the preservation of food, beverage, aquatic, and cosmetic products.Polymers 2019, 11, 1979 2 of 12 and KGO have many good properties, these functionalities can be further improved through certain molecular modifications. Various forms of KGM derivatives obtained by physical, chemical, and enzymatical modifications have been used in a range of different applications, including biodegradable films, medical and pharmaceutical materials, functional foods, and aerogel [10]. Thus, the modification of KGM and KGO gains much interest from numerous researchers because of their better performance in food applications.Kojic acid (KA), 5-hydroxy-2-hydroxymethyl-1,4-pyrone, is a weakly acidic secondary metabolite produced by aerobic fermentation of Aspergillus, Acetobacter, and Penicillium. KA has a variety of biological activities, including antibacterial, antifungal, antiviral, and antioxidant activities [16][17][18][19]. Therefore, KA and its derivatives have attracted much attention for their variety of biological activities.In aquatic product preservation, the most common challenges are water retention and bacterial inhibition. Foodborne pathogens and spoilage bacteria such as Staphylococcus aureus, Shewanella putrefaciens, Escherichia coli, and Salmonella enterica, which are common strains found in aquatic products [20][21][22]. Staphylococcus epidermidis is a bacterium that breeds on the epidermis of organisms. Most of them are non-pathogenic bacteria and a few can cause diseases. S. aureus is a commensal and opportunistic pathogen that can cause contamination of food products during preparation and processing [23]. S. putrefaciens is a marine, gram-negative bacterium which plays a role in the food industry as a spoilage bacterium of marine fish and chicken due to its ability to produce volatile sulfides, amines, and the fishy-smelling compound trimethylamine [24]. As one of the oligosaccharides...

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