Levan-typed fructooligosaccharide (LFOS), a β-2,6 linked oligofructose, displays the potential application as a prebiotic and therapeutic dietary supplement. In the present study, LFOS was synthesized using levansucrase from Bacillus amyloliquefaciens KK9 (LsKK9). The wild-type LsKK9 was cloned and expressed in E. coli, and purified by cation exchanger chromatography. Additionally, Y237S variant of LsKK9 was constructed based on sequence alignment and structural analysis to enhance the LFOS production. High-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD) analysis indicated that Y237S variant efficiently produced a higher amount of short-chain LFOS than wild type. Also, the concentration of enzyme and sucrose in the reactions was optimized. Finally, prebiotic activity assay demonstrated that LFOS produced by Y237S variant had higher prebiotic activity than that of the wild-type enzyme, making the variant enzyme attractive for food biotechnology.

Levan is a biopolymer composed of fructose chains covalently linked by β−2,6 glycosidic linkages. This polymer self−assembles into a nanoparticle of uniform size, making it useful for a wide range of applications. Also, levan exhibits various biological activities such as antioxidants, anti-inflammatory, and anti-tumor, that make this polymer very attractive for biomedical application. In this study, levan synthesized from Erwinia tasmaniensis was chemically modified by glycidyl trimethylammonium chloride (GTMAC) to produce cationized nanolevan (QA-levan). The structure of the obtained GTMAC−modified levan was determined by FT-IR, ¹H-NMR and elemental (CHN) analyzer. The size of the nanoparticle was calculated using the dynamic light scattering method (DLS). The formation of DNA/QA-levan polyplex was then investigated by gel electrophoresis. The modified levan was able to increase the solubility of quercetin and curcumin by 11-folds and 205-folds, respectively, compared to free compounds. Cytotoxicity of levan and QA−levan was also investigated in HEK293 cells. This finding suggests that GTMAC−modified levan should have a potential application for drug and nucleic acid delivery.

There have been a relatively small number of studies on microplastics (MPs) in commercial freshwater prawns, although MP contamination in aquatic habitats is a global issue. This study presents the shapes, sizes, colors, and concentrations of microplastics discovered in 90 Macrostemum rosenbergii specimens gathered from three cultivated ponds in central Thailand. Microplastics in each prawn's four anatomical compartments (intestinal tract, hepatopancreas, muscle, and exoskeleton) were examined independently. MPs were detected in all studied specimens, with an average of 79.3 ± 2.92 MPs/individual. The intestinal tract had an average of 26.82 ± 0.92 MPs/individual, followed by the hepatopancreas at 21.09 ± 1.11 MPs/individual, muscle at 16.70 ± 0.63 MPs/individual, and the exoskeleton at 14.69 ± 0.65 MPs/individual. Fibers were predominant over fragments and spheres, with an average of 58.84%, 41.0%, and 0.16%. The most commonly observed microplastics were between 100 and 250 µm and 250 and 500 µm. Blue (58.09%) was the most common color of microplastic, followed by white/transparent (33.30%), red (7.06%), violet (1.42%), green (0.10%), and yellow (0.03%), respectively. Polyethylene terephthalate, polyvinyl acetate, and polyacrylonitrile-co-butadiene were the most frequent polymers, accounting for nearly 61% of all MPs found. There was a significant correlation (r = 0.85, p = 0.000, and r = 0.054, p = 0.002) between the weights of male and female prawn organs and the number of microplastics found in each. Male and female prawns showed no difference in microplastics larger than 500 µm across all organs (p > 0.05). This finding suggests that prawns in central Thailand's cultivated ponds are not free of microplastic pollution. The information offered here allows us to better understand the potential problems connected with human consumption of various tissues from contaminated prawns.