ABSTRACT

The gut microbiome is a vast reservoir of microbes, some of which produce antimicrobial peptides called bacteriocins that may inhibit specific bacteria associated with disease. Fusobacterium nucleatum is an emerging human bacterial pathogen associated with gastrointestinal diseases including colorectal cancer (CRC). In this study, fecal samples of healthy donors were screened for potential bacteriocin-producing probiotics with antimicrobial activity against F. nucleatum. A novel isolate, designated as Streptococcus salivarius DPC6993 demonstrated a narrow-spectrum of antimicrobial activity against F. nucleatum in vitro. In silico analysis of the S. salivarius DPC6993 genome revealed the presence of genes involved in the production of the bacteriocins salivaricin A5 and salivaricin B. After 6 h in a colon fermentation model, there was a significant drop in the number of F. nucleatum in samples that had been simultaneously inoculated with S. salivarius DPC6993 + F. nucleatum DSM15643 compared to those inoculated with F. nucleatum DSM15643 alone (mean ± SD: 9243.3 ± 3408.4 vs 29688.9 ± 4993.9 copies/μl). Furthermore, 16S rRNA amplicon analysis revealed a significant difference in the mean relative abundances of Fusobacterium between samples inoculated with both S. salivarius DPC6993 and F. nucleatum DSM15643 (0.05%) and F. nucleatum DSM15643 only (0.32%). Diversity analysis indicated minimal impact exerted by S. salivarius DPC6993 on the surrounding microbiota. Overall, this study highlights the ability of a natural gut bacterium to target a bacterial pathogen associated with CRC. The specific targeting of CRC-associated pathogens by biotherapeutics may ultimately reduce the risk of CRC development and positively impact CRC outcomes.

摘要

肠道微生物组是一个巨大的微生物库，其中一些微生物产生称为细菌素的抗菌肽，可以抑制与疾病相关的特定细菌。具核梭杆菌是一种新兴的人类细菌病原体，与包括结直肠癌 (CRC) 在内的胃肠道疾病有关。在这项研究中，对健康捐赠者的粪便样本进行了筛选，以寻找具有抗具核梭菌活性的潜在产生细菌素的益生菌。一种新的分离株，命名为唾液链球菌DPC6993，在体外证明了对 F. nucleatum 的窄谱抗菌活性。唾液链球菌的计算机分析DPC6993 基因组显示存在与细菌素 salivaricin A5 和 salivaricin B 产生有关的基因。在结肠发酵模型中 6 小时后，同时接种S的样品中具核梭菌的数量显着下降. salivarius DPC6993 +  F. nucleatum DSM15643 与单独接种F. nucleatum DSM15643 的相比（平均值 ± SD：9243.3 ± 3408.4 vs 29688.9 ± 4993.9 拷贝/μl）。此外，16S rRNA 扩增子分析显示，接种S. salivarius DPC6993 和F. nucleatum的样品之间梭杆菌的平均相对丰度存在显着差异仅 DSM15643 (0.05%) 和具核梭菌 DSM15643 (0.32%)。多样性分析表明S. salivarius DPC6993 对周围微生物群的影响最小。总体而言，这项研究强调了天然肠道细菌靶向与 CRC 相关的细菌病原体的能力。生物治疗剂对 CRC 相关病原体的特异性靶向可能最终降低 CRC 发展的风险并对 CRC 结果产生积极影响。