国产乳粉中嗜热杆菌的生物膜特性及其危害机制研究

A previous study on microbial contamination confirmed that thermophilic bacilli contamination in domestic milk was serious, which affected the quality and safety of domestic milk powder. Biofilm formation on the dairy processing lines is an important source of thermophilic bacilli contamination of dairy products. The process of biofilm formation varies with species and environmental changes The process of thermophile contamination and subsequent biofilm formation in dairy manufacturing plants is still not clearly understood. This project will analyze the influence of the cell surface physicochemical properties (including surface hydrophobicity, surface charge, surface proteins, extracellular polysaccharides, etc.), stainless steel surface properties, environmental changes and the synergistic or inhibitory between strains on thermophilic bacilli adhesion and biofilm formation on the surface of stainless steel, and further analyze the physiological properties of biofilms (including growth, maturity, spores generation and stability of the biofilm ) and its potential harm (including corruption activity release and the release of bacterial spores), and then clarify the mechanism of thermophilic bacilli biofilm formation and its hazards scientifically to provide the necessary foundation for developing measures to control contamination and improving the quality and safety of domestic milk powder. Moreover, this study will enrich and deepen the knowledge on the potential security risks of domestic milk powders especially for infant formula.

我们之前对乳粉微生物污染情况的研究证实国产乳粉嗜热杆菌污染严重，影响着乳粉的品质和安全。在生产线上形成生物膜是嗜热杆菌污染乳制品的重要来源，生物膜的形成过程因微生物物种和环境变化而不同，乳制品加工领域嗜热杆菌的生物膜形成机制并不明确。本课题旨在采用科学的研究方法和手段全面分析国产乳粉中的嗜热杆菌菌体表面的理化特性（包括表面疏水性、表面电荷、表面蛋白质、胞外多糖等）、不锈钢表面性质、环境变化及菌株间的协同或抑制作用对其在不锈钢表面粘附和形成生物膜的影响，进一步分析生物膜的生理学特性(包括生长、成熟、芽孢产生以及生物膜的稳定性)及其潜在危害性（包括腐败酶活性的释放、菌体及芽孢的释放），客观科学地阐明这些微生物的生物膜形成及危害机制，为制定污染控制措施，改善国产乳粉品质及保障安全提供必要研究基础。本项目的研究结果有助于丰富和加深对国产乳粉，尤其是婴儿配方乳粉潜在质量和安全风险的认知。

国产乳粉嗜热杆菌污染严重，影响着乳粉的品质和安全。在生产线上形成生物膜是嗜热杆菌污染乳制品的重要来源，生物膜的形成过程因微生物物种和环境变化而不同，本课题采用科学的研究方法和手段全面分析国产乳粉中的嗜热杆菌菌体表面的理化特性、不锈钢表面性质、环境变化及菌株间的协同或抑制作用对其在不锈钢表面粘附和形成生物膜的影响，进一步分析生物膜的生理学特性及潜在危害性。研究结果表明嗜热杆菌主要是通过菌体自身表面的疏水性及表面电荷与不锈钢表面之间发生相互吸引，粘附并进而形成稳定生物膜。生物膜会向周边物料释放活性菌体进而污染物料并带来致腐败风险。菌体粘附能力因菌种和菌株不同而有差异，并且受到温度、pH、所处基质以及清洗条件等多方面因素的影响。通过对影响菌体粘附的外部环境条件控制以及不锈钢表面的清洗处理，有可能抑制菌体粘附并清除嗜热杆菌生物膜。本研究结果丰富和加深对国产乳粉潜在质量和安全风险的认知，为乳粉生产过程中制定有效控制嗜热芽孢杆菌污染的措施提供必要的研究基础，有助于生产企业改进生产和清洗条件来有效控制乳粉中嗜热杆菌污染，改善国产乳粉品质保障安全。