Cucumber fermentations are one of the most important vegetable fermentations in the United States. The fermentation is usually driven by lactic acid bacteria (LAB) indigenous to fresh cucumbers. But LAB are greatly outnumbered by many Gram-negative bacteria on fresh cucumbers, which may influence the growth of LAB and the incidence of bloater defect (hollow cavities formed inside fermented cucumbers) leading to serious economic loss to the pickle industry. Rapid elimination of Gram-negative bacteria is crucial to the dominance of LAB and the reduction of bloater defect in the fermentation. Various factors can affect the viability of Gram-negative bacteria in cucumber fermentation. Bacteriophages (phages) may be one of such factors. This study explored the abundance, diversity, and functional role of phages infecting Gram-negative bacteria in a commercial cucumber fermentation. Cover brine samples were taken from a commercial fermentation tank over a 30-day period. On day 1 and day 3 of the fermentation, 39 Gram-negative bacteria and 26 independent phages were isolated. Nearly 67% of Gram-negative bacterial isolates were susceptible to phage infection. Phage hosts include Enterobacter, Citrobacter, Escherichia, Pantoea, Serratia, Leclercia, Providencia, and Pseudomonas species. About 88% of the isolated phages infected the members in the family Enterobacteriaceae and 58% of phages infected Enterobacter species. Eight phages with unique host ranges were characterized. These phages belong to the Myoviridae, Siphoviridae, or Podoviridae family and showed distinct protein profiles and DNA fingerprints. The infectivity of a phage against Enterobacter cancerogenus was evaluated in cucumber juice as a model system. The phage infection at the multiplicity of infection 1 or 100 resulted in a 5-log reduction in cell concentration within 3 h and rapidly eliminated its host. This study revealed the abundance and variety of phages infecting Gram-negative bacteria, particularly Enterobacteriaceae, in the commercial cucumber fermentation, suggesting that phages may play an important role in the elimination of Gram-negative bacteria, thereby facilitating the dominance of LAB and minimizing bloater defect. To our knowledge, this is the first report on the ecology of phages infecting Gram-negative bacteria in commercial cucumber fermentations.

黄瓜发酵是美国最重要的蔬菜发酵之一。发酵通常由新鲜黄瓜固有的乳酸菌（LAB）驱动。但是新鲜黄瓜上的许多革兰氏阴性细菌远远超过了乳酸菌，这可能会影响乳酸菌的生长和膨胀缺陷（发酵黄瓜内部形成的空心空腔）的发生，从而给腌制业带来严重的经济损失。快速消除革兰氏阴性细菌对于控制LAB的优势和减少发酵中膨胀剂缺陷至关重要。各种因素均可影响黄瓜发酵中革兰氏阴性菌的生存能力。噬菌体（噬菌体）可能是此类因素之一。这项研究探索了丰富性，多样性，黄瓜发酵中噬菌体感染革兰氏阴性菌的功能和功能 在30天的时间里，从商业发酵罐中采集了卤水样本。在发酵的第1天和第3天，分离出39个革兰氏阴性细菌和26个独立的噬菌体。几乎67％的革兰氏阴性细菌分离株易感染噬菌体。噬菌体宿主包括肠杆菌， 柠檬杆菌， 埃希氏菌属， 潘托亚， 沙雷氏菌， 勒克莱西亚， 普罗维登西亚和 假单胞菌种类。大约88％的孤立噬菌体感染了家庭成员肠杆菌科 58％的噬菌体被感染 肠杆菌种类。表征了具有独特宿主范围的八个噬菌体。这些噬菌体属于肌病毒科， 剑叶病毒科， 要么 足病毒科家族，并显示出不同的蛋白质谱和DNA指纹图谱。噬菌体对肠杆菌Ë致癌性在黄瓜汁中作为模型系统进行了评估。感染数为1或100的噬菌体感染导致3小时内细胞浓度降低了5个对数，并迅速消除了其宿主。这项研究揭示了感染革兰氏阴性细菌的噬菌体数量众多且种类繁多，特别是肠杆菌科，在商品黄瓜发酵中，表明噬菌体可能在消除革兰氏阴性细菌中起重要作用，从而促进了LAB的优势并最小化了膨胀剂缺陷。据我们所知，这是关于在商业黄瓜发酵中感染革兰氏阴性细菌的噬菌体生态学的首次报道。