McPhillips Leah, O'Callaghan John, Shortiss Carmel, Jackson Stephen A, O'Leary Niall D
John Innes Centre, Norwich NR4 7UH, UK.
School of Microbiology, University College Cork, T12 K8AF Cork, Ireland.
Antibiotics (Basel). 2024 Oct 11;13(10):956. doi: 10.3390/antibiotics13100956.
Research-engaged academic institutions offer the opportunity to couple undergraduate education/citizen science projects with antimicrobial biodiscovery research. Several initiatives reflecting this ethos have been reported internationally (e.g., Small World, Tiny Earth, MicroMundo, Antibiotics Unearthed). These programs target soil habitats due to their high microbial diversity and promote initial screening with non-selective, nutrient media such as tryptic soy agar (TSA). However, evaluation of published outputs to date indicates that isolate recovery on TSA is consistently dominated by the genera , and . In this study, we evaluated the potential of soil extract agar to enhance soil isolate diversity and antibiosis induction outcomes in our undergraduate Antibiotics Unearthed research program. We comparatively screened 229 isolates from woodland and garden soil samples on both tryptic soy agar (TSA) and soil extract agar (SEA) for antimicrobial activity against a panel of clinically relevant microbial pathogens. On one or both media, 15 isolates were found to produce zones of clearing against respective pathogens. 16S rRNA gene sequencing linked the isolates with three genera: (7), (6), and (2). Six of the isolates and one demonstrated antimicrobial activity when screened on SEA, with no activity on TSA. Furthermore, incorporation of the known secondary metabolite inducer N acetyl-glucosamine (20 mM) into SEA media altered the pathogen inhibition profiles of 14 isolates and resulted in broad-spectrum activity of one isolate, not observed on SEA alone. In conclusion, SEA was found to expand the diversity of culturable isolates from soil and specifically enhanced the recovery of members of the genus . SEA was also found to be a superior media for antibiosis induction among isolates when compared to TSA. It was noted that isolates' antibiosis induction demonstrated a strain-specific response with respect to the growth media used. The authors propose SEA inclusion of in soil screening protocols as a cost-effective, complementary strategy to greatly enhance outcomes in undergraduate/citizen science-engaged antimicrobial biodiscovery initiatives.
从事研究的学术机构提供了将本科教育/公民科学项目与抗微生物生物发现研究相结合的机会。国际上已经报道了几项体现这种理念的倡议（例如，小世界、微小地球、微观世界、挖掘抗生素）。这些项目以土壤栖息地为目标，因为其微生物多样性高，并促进使用胰蛋白胨大豆琼脂（TSA）等非选择性营养培养基进行初步筛选。然而，对迄今为止已发表成果的评估表明，TSA上的分离物回收一直由 属、 属和 属主导。在本研究中，我们评估了土壤提取物琼脂在我们的本科挖掘抗生素研究项目中增强土壤分离物多样性和抗菌诱导结果的潜力。我们在胰蛋白胨大豆琼脂（TSA）和土壤提取物琼脂（SEA）上对来自林地和花园土壤样本的229个分离物进行了比较筛选，以检测其对一组临床相关微生物病原体的抗菌活性。在一种或两种培养基上，发现15个分离物对各自的病原体产生了抑菌圈。16S rRNA基因测序将这些分离物与三个属联系起来： 属（7个）、 属（6个）和 属（2个）。其中6个 属分离物和1个 属分离物在SEA上筛选时表现出抗菌活性，而在TSA上无活性。此外，将已知的次生代谢物诱导剂N-乙酰葡糖胺（20 mM）加入SEA培养基中，改变了14个分离物的病原体抑制谱，并导致1个 属分离物产生广谱活性，而单独在SEA上未观察到这种情况。总之，发现SEA扩大了土壤可培养分离物的多样性，并特别提高了 属成员的回收率。与TSA相比，还发现SEA是 属分离物抗菌诱导的优质培养基。值得注意的是， 属分离物的抗菌诱导表现出针对所用生长培养基的菌株特异性反应。作者建议在土壤筛选方案中纳入SEA，作为一种经济有效的补充策略，以大大提高本科/公民科学参与的抗微生物生物发现倡议的成果。
