Quintieri Laura, Fanelli Francesca, Zühlke Daniela, Caputo Leonardo, Logrieco Antonio Francesco, Albrecht Dirk, Riedel Katharina
Institute of Sciences of Food Production, Italian National Research Council, Bari, Italy.
Institute of Microbiology, University of Greifswald, Greifswald, Germany.
Front Microbiol. 2020 May 28;11:991. doi: 10.3389/fmicb.2020.00991. eCollection 2020.
In food chain, spp. cause spoilage by reducing shelf life of fresh products, especially during cold storage, with a high economic burden for industries. However, recent studies have shed new light on health risks occurring when they colonize immunocompromised patient tissues. Likewise to , they exhibit antibiotic resistance and biofilm formation, responsible for their spread and persistence in the environment. Biofilm formation might be induced by environmental stresses, such as temperature fluctuations causing physiological and metabolic changes exacerbating food spoilage (by protease and pigment synthesis), and the production of adhesion molecules, chemotactic or underestimated virulence factors. In order to provide a new insight into phenotypic biodiversity of spoilers isolated from cold stored cheese, in this work 19 spp. were investigated for biofilm, pigments, exopolysaccharide production and motility at low temperature. Only nine strains showed these phenotypic traits and the blue pigmenting cheese strain ITEM 17298 was the most distinctive. In addition, this strain decreased the survival probability of infected larvae, showing, for the first time, a pathogenic potential. Genomic and proteomic analyses performed on the ITEM 17298 planktonic cells treated or not with lactoferrin derived antibiofilm peptides allowed to reveal specific biofilm related-pathways as well as proteins involved in pathogenesis. Indeed, several genes were found related to signaling system by cGMP-dependent protein kinases, cellulose, rhamnolipid and alginate synthesis, antibiotic resistance, adhesion and virulence factors. The proteome of the untreated ITEM 17298, growing at low temperature, showed that most of the proteins associated with biofilm regulation, pigmentation motility, antibiotic resistance and pathogenecity were repressed, or decreased their levels in comparison to that of the untreated cultures. Thus, the results of this work shed light on the complex pathways network allowing psychrotrophic pseudomonads to adapt themselves to food-refrigerated conditions and enhance their spoilage. In addition, the discovery of virulence factors and antibiotic resistance determinants raises some questions about the need to deeper investigate these underestimated bacteria in order to increase awareness and provide input to update legislation on their detection limits in foods.
在食物链中，假单胞菌属（Pseudomonas spp.）通过缩短新鲜产品的保质期导致食品变质，尤其是在冷藏期间，给相关产业带来了沉重的经济负担。然而，最近的研究揭示了它们在免疫功能低下患者组织中定殖时所产生的健康风险。与其他细菌类似，它们表现出抗生素抗性和生物膜形成能力，这导致它们在环境中传播和持续存在。生物膜的形成可能由环境压力诱导，例如温度波动导致生理和代谢变化，加剧食品变质（通过蛋白酶和色素合成），以及产生粘附分子、趋化因子或未被充分认识的毒力因子。为了深入了解从冷藏奶酪中分离出的假单胞菌属腐败菌的表型生物多样性，本研究对19株假单胞菌属菌株进行了低温下生物膜、色素、胞外多糖产生及运动性的研究。只有9株菌株表现出这些表型特征，其中蓝色色素沉着的奶酪菌株ITEM 17298最为独特。此外，该菌株降低了被感染的果蝇幼虫的存活概率，首次显示出致病潜力。对经乳铁蛋白衍生的抗生物膜肽处理或未处理的ITEM 17298浮游细胞进行的基因组和蛋白质组分析，揭示了与生物膜相关的特定途径以及参与致病过程的蛋白质。实际上，发现了几个与环鸟苷酸依赖性蛋白激酶信号系统、纤维素、鼠李糖脂和藻酸盐合成、抗生素抗性、粘附和毒力因子相关的基因。在低温下生长的未处理的ITEM 17298的蛋白质组显示，与生物膜调节、色素沉着运动、抗生素抗性和致病性相关的大多数蛋白质被抑制，或者与未处理培养物相比其水平降低。因此，本研究结果揭示了允许嗜冷假单胞菌适应食品冷藏条件并增强其腐败能力的复杂途径网络。此外，毒力因子和抗生素抗性决定因素的发现引发了一些问题，即是否需要更深入地研究这些未被充分认识的细菌，以提高认识并为更新食品中它们的检测限立法提供依据。
