Safety evaluations of alternansucrase enzyme expressed in Escherichia coli shows no adverse effects in vivo and in vitro

Background Alternansucrase is a glucansucrase enzyme that mainly functions in synthesis of glucan-like polysaccharides and can be used for production of novel oligosaccharides and polysaccharides having low glycemic index and prebiotics properties which makes them ideal candidates as dietary fibers and food. From a regulatory perspective, it is necessary to prove the safety of alternansucrase before it can be used in any application as it is a novel enzyme and has not been historically used in food processing. Objectives Alternansucrase obtained from Escherichia coli was subjected to toxicological tests to determine its safety for use in various industrial applications. Design Toxicity studies were conducted at acute oral and repeated sub-chronic (14 days and 90 days) levels in rats following the OECD guidelines. The genotoxicity studies were conducted using the bacterial reverse mutation test as well as in vitro mammalian cell micronucleus test as per the OECD guidelines. Results Alternansucrase did not induce any clinical abnormalities or mortality in rats at the dose level of 2000 mg/kg of body weight in the acute oral toxicity test. A 90-day sub chronic repeated dose oral toxicity study with alternansucrase at and up to dose of 1000 mg TOS/kg of body weight did not show any treatment-related significant toxicological effects on body weight, food consumption, organ weights, hematological and clinical chemistry, or histopathology parameters. Alternansucrase was found to be non-mutagenic up to 5000 µg TOS/plate concentration in the bacterial reverse mutation test. Alternansucrase was determined to be non-clastogenic and non-aneugenic up to the test concentration of 1250 µg TOS/mL during the in vitro mammalian cell micronucleus test. Conclusion The lethal dose (LD50) based on this study is greater than 2000 mg/kg body weight, which falls into the category 5 criteria of Globally Harmonized System (GHS). No-Observed-Adverse-Effect-Level (NOAEL) was concluded to be greater than 1000 mg TOS/kg per day. The studies taken together substantiate the safety of alternansucrase enzyme in various food and associated industries. The present study paves a future for safe use of alternansucrase in varied industrial applications.