Identification of bacterial contaminants from calcium carbonate filler production lines and an evaluation of biocide based decontamination procedures

The aim of this study was to analyze the bacterial community in the production line of a calcium carbonate filler production company and to investigate possible causes for bacterial presence. Throughout 2012, 24 carbonate slurry and six groundwater samples were analyzed. <i>Pseudomonas</i> and <i>Microbacterium</i> were the most frequent contaminants in the slurry, whereas <i>Pseudomonas</i> and <i>Brevundimonas</i> dominated the groundwater samples. Of the 43 different bacterial strains isolated, only five were found both in the slurry and the groundwater, indicating that the latter was not a major source of contamination. The efficacy of 54 commercial biocidal formulations was tested against an artificial bacterial consortium composed of selected slurry isolates. A formulation containing 7.5–15% (v v^–1) bronopol and 1.0–2.5% (v v^–1) [chloroisothiazolinone (CIT) + methylisothiazolinone (MIT)] exhibited the highest efficacy. Of the possible causes for bacterial presence, sporogenesis and biocide adsorption to carbonate particles were found to be less probable compared to bacterial adsorption to particles, and the acquisition of resistance to biocides.

本研究旨在分析某碳酸钙填料生产企业生产线内的细菌群落，并探究细菌污染的潜在成因。2012年全年，研究人员共采集并分析了24份碳酸盐浆液样本与6份地下水样本。浆液样本中检出频率最高的污染物为假单胞菌属（*Pseudomonas*）与微杆菌属（*Microbacterium*），而地下水样本中的优势菌群则为假单胞菌属与短波单胞菌属（*Brevundimonas*）。在所分离得到的43株不同细菌菌株中，仅有5株同时在浆液与地下水样本中被检出，这表明地下水并非该污染的主要来源。研究人员针对由筛选出的浆液分离菌株构建的人工细菌群落，测试了54种商用杀菌制剂的抑菌效果。其中，含有7.5%~15%（体积比）溴硝醇（bronopol），以及总占比为1.0%~2.5%（体积比）的氯异噻唑啉酮（CIT）与甲基异噻唑啉酮（MIT）复配体系的制剂，抑菌效能最优。在该细菌污染的潜在成因中，相较于细菌吸附于颗粒表面以及菌株获得杀菌剂抗性两种因素，芽孢形成与杀菌剂吸附于碳酸盐颗粒表面的可能性更低。