Posgrado en Biociencias, Universidad de Guanajuato Campus Irapuato-Salamanca, División de Ciencias de la Vida, Irapuato, Guanajuato, 36500, México.
Departamento de Alimentos, Universidad de Guanajuato Campus Irapuato-Salamanca, División de Ciencias de la Vida, Irapuato, Guanajuato, 36500, México.
Probiotics Antimicrob Proteins. 2023 Aug;15(4):955-966. doi: 10.1007/s12602-022-09952-2. Epub 2022 May 24.
Thurincin H, a bacteriocin produced by Bacillus thuringiensis, exhibits antibacterial activity against Gram-positive and Gram-negative bacteria. While much is known about its expression and antimicrobial spectrum, its hemolytic property has yet to be established. In this study, thurincin H was produced in a plasmid-free acrystalliferous strain of B. thuringiensis (Bt CryB) that naturally lacked antimicrobial and hemolytic activities. When grown in Tryptic Soy Broth (TSB), the bacteriocin's maximal production in Bt CryB harboring the thurincin H genetic cluster (Bt CryB/pThur) was observed at 24 h. Thurincin H was purified as a sole peptide of ~5 kDa using three purification steps, i.e., salt precipitation, ultrafiltration, and gel filtration chromatography. The bacteriocin showed inhibitory activity against B. cereus (5631 U), Bt CryB (8827 U), E. faecium wild type (11,197 U), and E. faecium ATCC 19,434 (6950 U), but not against Bt CryB/pThurH and Bt CryB/pThurHΔThnA. In addition, a minimum inhibitory concentration (MIC) of 5.0 μg/mL against B. cereus 183 was observed. In silico predictions suggested that thuricin H lacks hemolytic activity, which was validated in vitro using 4 × the MIC, i.e., 20 μg/ml. Our data lay a foundation for the potential safe use of thurincin H as an antibacterial peptide for medical use, in food products, and for expression in probiotic bacteria.
苏云金菌素 H 是一种由苏云金芽孢杆菌产生的细菌素，对革兰氏阳性和革兰氏阴性细菌均具有抗菌活性。虽然人们对其表达和抗菌谱了解较多，但它的溶血特性尚未确定。在这项研究中，苏云金菌素 H 是在一种无质粒的不结晶苏云金芽孢杆菌（Bt CryB）中产生的，该菌株天然缺乏抗菌和溶血活性。当在胰蛋白酶大豆肉汤（TSB）中生长时，在携带苏云金菌素 H 基因簇的 Bt CryB 中（Bt CryB/pThur）观察到细菌素的最大产量出现在 24 小时。苏云金菌素 H 是通过三种纯化步骤，即盐沉淀、超滤和凝胶过滤色谱法，作为唯一的 5kDa 多肽进行纯化的。该细菌素对蜡状芽孢杆菌（5631 U）、Bt CryB（8827 U）、野生粪肠球菌（11197 U）和粪肠球菌 ATCC 19434（6950 U）具有抑制活性，但对 Bt CryB/pThurH 和 Bt CryB/pThurHΔThnA 没有抑制活性。此外，对蜡状芽孢杆菌 183 的最小抑菌浓度（MIC）为 5.0μg/ml。计算机预测表明苏云金菌素 H 缺乏溶血活性，这在体外使用 4 倍 MIC，即 20μg/ml 时得到了验证。我们的数据为苏云金菌素 H 作为一种用于医疗、食品和益生菌细菌表达的抗菌肽的潜在安全使用奠定了基础。
