Prakash Palkar Omkar, Rayasam Keerthi, Peddireddy Vidyullatha, Chaitanya Kolluru Viswanatha
Department of Life Sciences, GITAM School of Science, GITAM (Deemed to Be University), Visakhapatnam, Andhra Pradesh, 530045, India.
Department of Nutrition Biology, School of Interdisciplinary & Applied Sciences, Central University of Haryana, Jant-Pali, Mahendergarh, Haryana, 123031, India.
Int Microbiol. 2024 Sep 26. doi: 10.1007/s10123-024-00597-5.
Levan, an exopolysaccharide, has applications in the medical and food sectors. Under natural conditions, levan is produced at a low concentration by microorganisms. This current study focuses on optimizing levan production by a one-variable-at-a-time approach from a novel marine bacterium, Calidifontibacillus erzurumensis LEV207. The growth and levansucrase production by C. erzurumensis LEV207 were studied to optimize the media components and conditions. Sucrose and yeast extract proved to be a good levansucrase inducer. The pH of 6.0 and temperature of 30 °C, along with MgSO as salt, increased the enzyme activity. Sucrose and yeast extract at the concentration of 50% and 1%, respectively, produced the maximum enzyme activity of 427.4 µmol/mL/min after 48 h of incubation. Sevag reagent was used for the purification of levan. The optimization process increased the levan (EPSLEV207) production sevenfold with a final yield of 65.58 g/L. To confirm the structure and nature of EPSLEV207, NMR and XRD were performed, and the functional groups present in EPSLEV207 were determined using FTIR. Chemical hydrolysis of levan confirmed fructose as the monomer, making EPSLEV207 a homopolysaccharide. EPSLEV207 exhibited 49% and 22% radical scavenging activity against DPPH and ABTS radicals, respectively, and promoted the growth of probiotic strain. EPSLEV207 showed an 88% water solubility index and 78% water retention capacity. The optimization process has increased the yield of levan, highlighting the potential of C. erzurumensis LEV207 to be a viable option for industrial applications.
果聚糖是一种胞外多糖，在医疗和食品领域均有应用。在自然条件下，微生物产生果聚糖的浓度较低。本研究聚焦于采用逐一变量法，从一种新型海洋细菌——埃尔祖鲁姆热泉芽孢杆菌LEV207优化果聚糖的生产。对埃尔祖鲁姆热泉芽孢杆菌LEV207的生长和果聚糖蔗糖酶生产进行了研究，以优化培养基成分和条件。结果证明，蔗糖和酵母提取物是良好的果聚糖蔗糖酶诱导剂。pH值为6.0、温度为30℃，以及以硫酸镁作为盐，均可提高酶活性。蔗糖和酵母提取物的浓度分别为50%和1%时，孵育48小时后产生的最大酶活性为427.4微摩尔/毫升/分钟。采用Sevag试剂对果聚糖进行纯化。优化过程使果聚糖（EPSLEV207）产量提高了7倍，最终产量为65.58克/升。为确认EPSLEV207的结构和性质，进行了核磁共振（NMR）和X射线衍射（XRD）分析，并使用傅里叶变换红外光谱（FTIR）确定了EPSLEV207中存在的官能团。果聚糖的化学水解证实果糖为单体，这使得EPSLEV207成为一种同多糖。EPSLEV207对二苯基苦味酰基自由基（DPPH）和2,2'-联氮-双-3-乙基苯并噻唑啉-6-磺酸自由基（ABTS）的清除活性分别为49%和22%，并促进了益生菌菌株的生长。EPSLEV207的水溶性指数为88%，保水能力为78%。优化过程提高了果聚糖的产量，突出了埃尔祖鲁姆热泉芽孢杆菌LEV207在工业应用中成为可行选择的潜力。
