Characterization of a new efficient low molecular weight Bacillus subtilis NRC₁₆ levansucrase and its levan

Abstract

Screening of 18 bacterial honey isolates revealed that all the isolates were levansucrase producers. The most potent isolate that achieved the highest activity (45.66 U/ml) was identified as Bacillus subtilis NRC based on morphological examination and 16S rRNA. The results recorded the necessity of starch (5 g/L), baker's yeast (12.5 g/L), and AlCl 3 (5 mM) in improvement of the enzyme productivity. The Bacillus subtilis levansucrase was eluted as a single protein in one purification step. The enzyme molecular weight was (14 kDa). It showed its optimum activity at 45°C and could retain 60% of its activity after incubation at 50°C for 2 h. Its optimum activity was obtained at pH 8.2 and the enzyme showed great pH stability in both acidic and alkaline ranges.Unlike, most levansucrases all tested metals had an adverse effect in enzyme activity. The enzyme had antioxidant activities and were characterized as spherical micro-and nanoparticles by transmission electron microscopy. The effect of growth conditions and medium composition in levan structure and its fibrinolytic activity was evaluated. K E Y W O R D S

Secretion of Bacillus amyloliquefaciens Levansucrase from Bacillus subtilis and Its Application in the Enzymatic Synthesis of Levan

“…The molecular mass of Ba-SacB is ∼55 kDa, similar to those of most levansucrases from various microbial sources, which range from 45 to 90 kDa. 27,50,51 The enzyme assay confirmed that Ba-SacB was active without trypsin, probably because B. subtilis 168 secretes high levels of extracellular proteases, which partly removed SP amyQ releasing a fraction of the active enzyme.…”

“…The specific enzyme activity was calculated by dividing the enzyme activity by the protein content. 27,28 The optimized enzymatic reaction conditions were determined using different temperature and initial pH values. Ba-SacB (6 μg/mL) was added to Na 2 HPO 4 /NaH 2 PO 4 buffer (0.1 M, pH 6) containing 10 mM CaCl 2 and a 0.1 M sucrose, which was incubated at different temperatures (20,30,40,50, and 60 °C) for 30 min.…”

Evaluation of Different Bacterial Honey Isolates As Probiotics And Their Efficient Roles In Cholesterol Reduction

“…The selection of a probiotic bacteria based on levansucrase production was mentioned by Hamdy et al (2017;. Previously, most of the bacteria isolated from honey form the levan polymer by the action of a levansucrase (Salama et al 2019;Esawy et al (2011;; Gamal et al 2020]. Levan known as prebiotic could increase the bene cial bacteria in the stomach and has a bene cial effect on public health protection (Ragab et al 2020).…”

Fructanogenic traits in halotolerant Bacillus licheniformis OK12 and their predicted functional significance

“…Although almost all fructanogenic Bacillus species have been reported to produce levan-type fructans, FT enzymes from Salipaludibacillus agaradhaerens WDG185 (basionym: Bacillus agaradhaerens), another halotolerant species from the family Bacillaceae, were shown to synthesize short-chain (DP = 3-25) inulins (Kralj et al 2018), indicating that although a rare phenomenon, some Bacillaceae species may also be able to produce inulin-type fructans. The literature is rich with the reports of levan-producing Bacillus species, especially Bacillus subtilis (Salama et al 2019), Bacillus megaterium (Yu et al 2016) andB. licheniformis (Gojgic-Cvijovic et al 2019).…”