Abstract：
Viral diseases are a serious threat to humans while the most antiviral drugs have low efficiency and side effects on human health. Therefore, using microbial biopolymers as the drugs alternate to treat viral infections seems cost-effective and human friendly option. In the present study, thirty-four exopolysaccharides (EPSs) producing bacteria were isolated, and EPSs production capacity of five salt-tolerant isolates was determined under 0, 100 and 150 mM NaCl. Among these, two isolates exhibiting high anti-coliphage activity were identified through 16S rRNA gene analysis. Moreover, the EPSs were characterized by Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis, and their composition was determined. Five salt-tolerant bacteria (MK1, MK2, MK10, MK22 and MK29) exhibited higher production of EPSs at 100 mM NaCl compared to that under non-saline control. At 100 mM NaCl, the yield of EPSs ranged between 105 and 330 mg 100 mL-1 broth. The EPSs produced by the isolates MK1 and MK2 exhibited higher anti-coliphage activity (plaque forming unit decreased from 43 × 106 mL-1 to 3 × 106 and 4 × 106 mL-1, respectively), and were comprised of glucose, fructose, galactose, sucrose, lactose and xylose sugars. FTIR spectroscopy depicted that EPSs are mainly composed of hydroxyl, aliphatic, carboxyl, sulfate and phosphate functional groups, which could have bound coliphage and thus conferred higher anti-coliphage activities to the EPSs. Phylogenetic analysis revealed that MK1 and MK2 isolates formed clades within genus Priestia and Bacillus sequences, respectively. High EPSs production capacity of bacterial isolates under saline condition and high anti-coliphage activity of the EPSs implies that bacterial biopolymers could be useful in antiviral drugs therapy.
摘要：
病毒性疾病严重威胁着人类，而大多数抗病毒药物对人类健康具有低效率和副作用。因此,使用微生物生物聚合物作为替代药物来治疗病毒感染似乎是具有成本效益和人类友好的选择。在本研究中,分离出34种产生胞外多糖(EPS)的细菌，在0、100和150mMNaCl下确定了5种耐盐分离株的EPSs生产能力。其中,通过16SrRNA基因分析鉴定出两个具有高抗大肠杆菌噬菌体活性的分离株。此外，通过傅里叶变换红外(FTIR)光谱和X射线衍射(XRD)分析,并确定了它们的组成。与非盐水对照相比，五种耐盐细菌（MK1，MK2，MK10，MK22和MK29）在100mMNaCl下表现出更高的EPS产量。在100mMNaCl，EPS的产量在105至330mg100mL-1肉汤之间。分离物MK1和MK2产生的EPS表现出较高的抗大肠杆菌噬菌体活性（菌斑形成单位分别从43×106mL-1降低到3×106和4×106mL-1），由葡萄糖组成，果糖,半乳糖,蔗糖,乳糖和木糖糖。FTIR光谱表明，EPS主要由羟基组成，脂肪族,羧基，硫酸盐和磷酸盐官能团，可以结合大肠杆菌噬菌体，从而赋予EPS更高的抗大肠杆菌噬菌体活性。系统发育分析表明，MK1和MK2分离株在Priestia属和Bacillus序列中形成了进化枝，分别。在盐水条件下细菌分离株的高EPS生产能力和EPS的高抗大肠杆菌噬菌体活性意味着细菌生物聚合物可用于抗病毒药物治疗。
