表面材質及生理狀態對 Pantoea spp. 轉移至香瓜之行為影響

Abstract

細菌從污染源轉移至食品可能對食品安全及品質構成威脅，因其增加食源性疾病及食品腐敗的風險。本實驗室先前分別從香瓜及截切小黃瓜中分離出兩株具高度生物膜形成能力之 Pantoea 屬菌株，分別為 P. vagans M17 及 P. eucrina B1-6，其中 P. vagans M17 具導致香瓜腐敗之能力。本研究旨在探討上述兩株菌從受污染之食品接觸面轉移至香瓜之行為，並聚焦於不同接觸面材質及細菌生理狀態—浮游態和生物膜狀態—對轉移行為之影響。以微量孔盤法評估生物膜生成能力，結果顯示 P. eucrina B1-6之生物膜生成能力較 P. vagans M17 強。接著，本研究在不鏽鋼、玻璃及聚苯乙烯三種常見食品接觸面材質上進行生物膜培養，結果顯示表面材質對生物膜內菌數及生物膜生物量皆無顯著影響，且方片、菌株之表面特性及菌株自聚集能力，與生物膜生成之關聯性不明顯。在轉移行為的結果中，本研究應用數學模型擬合多次連續接觸轉移曲線，其中以對數線性模型擬合效果最佳。轉移率及轉移曲線下降速率參數皆顯示方片材質對 P. eucrina B1-6 轉移至香瓜具有一定程度的影響，不鏽鋼及玻璃表面的生物膜在初期轉移比例較高，而聚苯乙烯上的生物膜則展現持續性汙染的風險。另一方面，Pantoea 屬之浮游態細胞與生物膜細胞間轉移率存在顯著差異，然而不同菌株受生理狀態所影響的趨勢並不一致；觀察連續轉移曲線，皆以浮游態細胞能維持較穩定的轉移菌量，其中，浮游態 P. vagans M17 因其高轉移率及緩慢降低的連續轉移菌量，顯示出較高的微生物汙染潛力。本研究為不同加工情境下的細菌轉移行為提供初步且具價值之見解，期望能為未來制定有效污染管控策略提供相關科學依據，並促進截切蔬果加工廠衛生管理的優化。

Bacterial transfer from contamination sources to food poses significant safety and quality concerns, as it increases the risk of foodborne illnesses and spoilage. Previous studies from our lab have isolated two strong biofilm-forming Pantoea spp. strains, P. vagans M17 and P. eucrina B1-6, from melon and fresh-cut cucumber, respectively. Notably, P. vagans M17 has been associated with melon spoilage. This study aimed to investigate the transfer dynamics from contaminated coupons to melon of these two strains, focusing on the influence of different contact surface materials and the physiological state of bacteria, including planktonic and biofilm-associated forms. A 96-well plate biofilm formation assay revealed that P. eucrina B1-6 has a stronger biofilm formation ability than P. vagans M17. Subsequently, biofilms were cultivated on three common food-contact surface materials—stainless steel, glass, and polystyrene—and evaluated for biofilm cell counts and biomass. Results demonstrated that the surface materials did not significantly affect biofilm formation. Additionally, the surface characteristics of both the bacteria and the coupons, as well as the bacteria’s autoaggregation abilities, showed no clear relation to biofilm formation. Mathematical modeling was applied to fit the succession contact transfer data, with the Log-linear model providing the best fit. Both transfer rate and the decline-rate parameter (a-value) revealed that surface material influenced the transfer of P. eucrina B1-6 biofilms: biofilms on stainless steel and glass showed higher transfer rates, whereas those on polystyrene exhibited slower declines in transferred cell numbers during successive contacts, indicating potential for persistent contamination. Additionally, transfer rates differed significantly between Pantoea spp. planktonic and biofilm cells, and planktonic cells exhibited more stable transfer curves. In particular, planktonic P. vagans M17 showed high transfer rate and a stable curve, indicating greater potential for food contamination. This study may provide preliminary and valuable insights into bacterial transfer under different food processing scenarios, which could inform future strategies to control contamination and improve hygiene practices in fresh-cut produce processing.