Coronas Roberta, Zara Giacomo, Gallo Antonio, Rocchetti Gabriele, Lapris Marco, Petretto Giacomo Luigi, Zara Severino, Fancello Francesco, Mannazzu Ilaria
Department of Agricultural Sciences, University of Sassari, Sassari, Italy.
Department of Animal Science, Food and Nutrition (DIANA), Faculty of Agricultural, Food and Environmental Sciences, Università Cattolica del Sacro Cuore, Piacenza, Italy.
Front Microbiol. 2023 Jul 31;14:1223741. doi: 10.3389/fmicb.2023.1223741. eCollection 2023.
Dairy propionibacteria are Gram positive Actinomycetota, routinely utilized as starters in Swiss type cheese making and highly appreciated for their probiotic properties and health promoting effects. In this work, within the frame of a circular economy approach, 47 and spp. were isolated from goat cheese and milk, and ewe rumen liquor, and characterized in view of their possible utilization for the production of novel pro-bioactive food and feed on scotta, a lactose rich substrate and one of the main by-products of the dairy industry. The evaluation of the Minimum Inhibitory Concentration (MIC) of 13 among the most common antibiotics in clinical practice revealed a general susceptibility to ampicillin, gentamycin, streptomycin, vancomycin, chloramphenicol, and clindamycin while confirming a lower susceptibility to aminoglycosides and ciprofloxacin. Twenty-five isolates, that proved capable of lactose utilization as the sole carbon source, were then characterized for functional and biotechnological properties. Four of them, ascribed to species, and harboring resistance to bile salts (growth at 0.7-1.56 mM of unconjugated bile salts), acid stress (>80% survival after 1 h at pH 2), osmostress (growth at up to 6.5% NaCl) and lyophilization (survival rate > 80%), were selected and inoculated in scotta. On this substrate the four isolates reached cell densities ranging from 8.11 ± 0.14 to 9.45 ± 0.06 Log CFU mL and proved capable of producing different vitamin B9 vitamers after 72 h incubation at 30°C. In addition, the semi-quantitative analysis following the metabolomics profiling revealed a total production of cobalamin derivatives (vitamin B12) in the range 0.49-1.31 mg L, thus suggesting a full activity of the corresponding biosynthetic pathways, likely involving a complex interplay between folate cycle and methylation cycle required in vitamin B12 biosynthesis. These isolates appear interesting candidates for further investigation regarding the production of pro-bioactive scotta.
乳源丙酸杆菌是革兰氏阳性放线菌，常用于瑞士型奶酪制作的发酵剂，因其益生菌特性和促进健康的作用而备受赞誉。在这项工作中，在循环经济方法的框架内，从山羊奶酪、牛奶和母羊瘤胃液中分离出47株丙酸杆菌属和谢氏丙酸杆菌，并鉴于它们可能用于以富含乳糖的底物斯科塔（乳制品行业的主要副产品之一）生产新型益生元活性食品和饲料进行了表征。对临床实践中13种最常见抗生素的最低抑菌浓度（MIC）评估表明，这些菌株对氨苄青霉素、庆大霉素、链霉素、万古霉素、氯霉素和克林霉素普遍敏感，同时证实对氨基糖苷类和环丙沙星的敏感性较低。然后对25株能够以乳糖作为唯一碳源利用的分离株进行了功能和生物技术特性表征。其中4株归为丙酸杆菌属，具有耐胆盐能力（在0.7 - 1.56 mM未结合胆盐条件下生长）、耐酸应激能力（在pH 2条件下1小时后存活率>80%）、耐渗透压能力（在高达6.5% NaCl条件下生长）和冻干能力（存活率>80%），被挑选出来接种到斯科塔中。在这种底物上，这4株分离株的细胞密度达到8.11±0.14至9.45±0.06 Log CFU/mL，并在30°C孵育72小时后证明能够产生不同的维生素B9异构体。此外，代谢组学分析后的半定量分析显示钴胺素衍生物（维生素B12）的总产量在0.49 - 1.31 mg/L范围内，因此表明相应生物合成途径具有完全活性，可能涉及维生素B12生物合成中叶酸循环和甲基化循环之间的复杂相互作用。这些分离株似乎是进一步研究生产益生元活性斯科塔的有趣候选菌株。
