Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón (IA2), Universidad de Zaragoza-CITA, Zaragoza, Spain.
Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón (IA2), Universidad de Zaragoza-CITA, Zaragoza, Spain; Departamento de Ciencias Naturales, Facultad de Ciencias y Tecnología, Universidad Tecnológica de Panamá, Campus Metropolitano Víctor Levi Sasso, Panamá, Panamá.
Int J Food Microbiol. 2020 Apr 16;319:108495. doi: 10.1016/j.ijfoodmicro.2019.108495. Epub 2019 Dec 28.
Bovine lactoferrin (bLF) is an iron-binding glycoprotein used in functional and therapeutic products due to its biological properties, the most important being its antimicrobial activity. In this study, hydrolysates of bovine lactoferrin (bLFH) obtained with pepsin, chymosin and microbial rennet were assayed against Cronobacter sakazakii (10 CFU/mL) in different media: phosphate buffered saline (PBS), bovine skim milk and whey, and reconstituted powdered infant formula (PIFM). The results obtained have shown that hydrolysis of bLF enhances its antibacterial activity against C. sakazakii. The three types of bLFH dissolved in PBS reduced C. sakazakii growth from a concentration of 0.1 mg/mL and inhibited it completely above 0.5 mg/mL, after 4 and 8 h of incubation at 37 °C. The three bLFH (1 and 2 mg/mL) did not show any antibacterial activity in skim milk, whey and reconstituted PIFM after 8 h of incubation at 37 °C. However, C. sakazakii growth was completely inhibited in whey when pepsin and chymosin bLFH (2 mg/mL) were combined with undigested bLF (2 mg/mL), after 8 h of incubation at 37 °C. On the other hand, the combination of any of the three hydrolysates with bLF showed very low activity in skim milk and practically no activity in reconstituted PIFM. Furthermore, the effect of temperature after reconstitution (4, 23 and 37 °C), on the antibacterial activity of bLF (2.5 and 5 mg/mL) in reconstituted PIFM contaminated with C. sakazakii (10-10 CFU/mL) was also investigated. bLF at 5 mg/mL significantly reduced (p < .05) the proliferation of C. sakazakii in reconstituted PIFM at 37 °C until 2 h. C. sakazakii did not grow at 4 °C for 6 days in reconstituted PIFM with or without bLF. The effect of microwave heating (450, 550 and 650 W for 5, 10 and 15 s) on the antibacterial activity and stability of bLF (2.5 mg/mL) in reconstituted PIFM contaminated with C. sakazakii (10-10 CFU/mL) was also studied. The antibacterial activity of bLF was maintained after treatments at 450 and 550 W for 5 s, which kept 94 and 89% of bLF immunoreactivity, respectively. Moreover, microwave treatments of reconstituted PIFM with or without bLF, at 650 W for 5 s, and at 450, 550 and 650 W for 10 and 15 s, completely inactivated C. sakazakii.
牛乳铁蛋白（bLF）是一种铁结合糖蛋白，由于其生物特性，特别是其抗菌活性，被用于功能性和治疗性产品。在这项研究中，用胃蛋白酶、凝乳酶和微生物凝乳酶水解的牛乳铁蛋白（bLFH）在不同的培养基中对阪崎克罗诺杆菌（10 CFU/mL）进行了检测：磷酸盐缓冲盐水（PBS）、牛脱脂乳和乳清，以及重组婴儿配方奶粉（PIFM）。结果表明，bLF 的水解增强了其对阪崎克罗诺杆菌的抗菌活性。三种类型的 bLFH 在 PBS 中溶解，在 37°C 孵育 4 和 8 小时后，从 0.1mg/mL 的浓度开始降低阪崎克罗诺杆菌的生长，并在 0.5mg/mL 以上完全抑制其生长。在 37°C 孵育 8 小时后，三种 bLFH（1 和 2mg/mL）在脱脂乳、乳清和重组 PIFM 中均未显示出任何抗菌活性。然而，当胃蛋白酶和凝乳酶 bLFH（2mg/mL）与未消化的 bLF（2mg/mL）结合时，在 37°C 孵育 8 小时后，乳清中的阪崎克罗诺杆菌生长完全被抑制。另一方面，在脱脂乳和重组 PIFM 中，任何三种水解物与 bLF 的组合活性都非常低，在重组 PIFM 中几乎没有活性。此外，还研究了重组 PIFM（含 10-10 CFU/mL 阪崎克罗诺杆菌）中 bLF（2.5 和 5mg/mL）在再配制后的温度（4、23 和 37°C）对其抗菌活性的影响。5mg/mL 的 bLF 显著减少（p <.05）了 37°C 下重组 PIFM 中阪崎克罗诺杆菌的增殖，直到 2 小时。在含有或不含有 bLF 的重组 PIFM 中，阪崎克罗诺杆菌在 4°C 下 6 天内未生长。还研究了微波加热（450、550 和 650 W 下 5、10 和 15 s）对含 10-10 CFU/mL 阪崎克罗诺杆菌的重组 PIFM 中 bLF（2.5mg/mL）的抗菌活性和稳定性的影响。在 450 和 550 W 下处理 5 s 后，bLF 的抗菌活性得以保持，分别保持了 94%和 89%的 bLF 免疫反应性。此外，在 650 W 下，无论是否含有 bLF，用微波处理重组 PIFM 5 s、450、550 和 650 W 10 和 15 s，均可完全使阪崎克罗诺杆菌失活。
Appl Environ Microbiol. 2013-1-11
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