de Brito Leandro Paes, da Silva Elaine Cristina, Lins Leandro Fragoso, Severo de Medeiros Rosália, Silva Francisca Crislândia Oliveira, Pastrana Lorenzo, Cavalcanti Iago Dillion Lima, de Britto Lira-Nogueira Mariane Cajubá, Cavalcanti Maria Taciana Holanda, Porto Ana Lúcia Figueiredo
Federal University of Pernambuco, Av. Prof. Moraes Rego, 1235 - Cidade Universitária, 50670-901, Recife, Pernambuco, Brazil.
Federal Rural University of Pernambuco, Street Dom Manuel de Medeiros, s/n - Dois Irmãos, 52171-900, Recife, Pernambuco, Brazil.
Int J Biol Macromol. 2024 Dec;282(Pt 4):136926. doi: 10.1016/j.ijbiomac.2024.136926. Epub 2024 Oct 31.
The aim of this study was to select the best exopolysaccharide (EPS) producer among the Enterococcus strains to optimize, characterize, and evaluate its biological properties. Among the eleven strains, Enterococcus faecium KT990028 was selected, and the production conditions were optimized: 16.3 % (w/v) sucrose, 0.70 % (w/v) yeast extract, 8.3 % (w/v) reconstituted skimmed milk, at 38 °C in 15 h of incubation, producing 2.880 g/L of EPS. High performance anion exchange chromatography (HPAEC) analysis revealed that the molecular weight was 166.98 kDa. HPAEC, spectroscopy (FTIR), and nuclear magnetic resonance (H NMR) analyses revealed that the EPS was a heteropolysaccharide composed of galactose (37.74 %), rhamnose (19.79 %), arabinose (17.71 %), glucose (9.50 %), fucose (7.93 %), and mannose (7.33 %). Scanning electron microscopy showed a three-dimensional microstructure in the form of decompressed plates, with wrinkles, and pores. By means of dynamic light scattering (DLS), the EPS showed an average size varying from 135.25 ± 10.56 nm and 410.60 ± 45.20 nm, as the concentration was increased from 0.5 mg/mL to 2.0 mg/mL, respectively. X-ray diffraction revealed that the EPS has an amorphous and crystalline nature, while thermogravimetric analysis indicated stability up to 400 °C. The antioxidant effect (5 mg/mL) against DPPH, ABTS, OH, and O was 64.50 ± 0.71 %, 47.50 ± 0.10 %, 68.36 ± 0.59 %, and 44.83 ± 0.86 %, respectively. It was also able to inhibit and biofilm disruption of Escherichia coli ATCC 25922 and Enterococcus faecalis ATCC 6057 and had an antimicrobial effect from 50 mg/mL for the strains of against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Listeria monocytogenes ATCC 19117, Staphylococcus aureus ATCC 6538, and Enterococcus faecalis ATCC 6057. Cell cytotoxicity carried out using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that the EPS was safe and promoted the proliferation of Vero cells. Thus, the results indicated that the EPS from E. faecium KT990028 is a promising functional biopolymer for possible applications in the food and pharmaceutical fields.
本研究的目的是在肠球菌菌株中筛选出最佳的胞外多糖（EPS）生产者，以优化、表征并评估其生物学特性。在11株菌株中，选择了粪肠球菌KT990028，并对其生产条件进行了优化：16.3%（w/v）蔗糖、0.70%（w/v）酵母提取物、8.3%（w/v）复原脱脂乳，在38℃下培养15小时，产EPS 2.880 g/L。高效阴离子交换色谱（HPAEC）分析显示其分子量为166.98 kDa。HPAEC、光谱（FTIR）和核磁共振（H NMR）分析表明，该EPS是一种杂多糖，由半乳糖（37.74%）、鼠李糖（19.79%）、阿拉伯糖（17.71%）、葡萄糖（9.50%）、岩藻糖（7.93%）和甘露糖（7.33%）组成。扫描电子显微镜显示其三维微观结构为解压板状，有皱纹和孔隙。通过动态光散射（DLS），随着浓度从0.5 mg/mL增加到2.0 mg/mL，EPS的平均尺寸分别从135.25±10.56 nm变化到410.60±45.20 nm。X射线衍射表明该EPS具有无定形和结晶性质，而热重分析表明其在400℃以下稳定。对DPPH、ABTS、OH和O的抗氧化作用（5 mg/mL）分别为64.50±0.71%、47.50±0.10%、68.36±0.59%和44.83±0.86%。它还能够抑制大肠杆菌ATCC 25922和粪肠球菌ATCC 6057的生物膜形成并破坏其生物膜，对大肠杆菌ATCC 25922、铜绿假单胞菌ATCC 27853、单核细胞增生李斯特菌ATCC 19117、金黄色葡萄球菌ATCC 6538和粪肠球菌ATCC 6057等菌株，从50 mg/mL起具有抗菌作用。使用3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐（MTT）法进行的细胞毒性试验表明，该EPS是安全的，并能促进Vero细胞的增殖。因此，结果表明粪肠球菌KT990028产生的EPS是一种有前景的功能性生物聚合物，可能在食品和制药领域得到应用。
