（五）、食品中常见的微生物Commonfoodbornemicroorganismsinfoods假单胞菌属：革兰氏阴性、极生鞭毛、可运动、不生芽孢、杆状，新鲜食品中的优势菌，常存在于土壤和水中，广泛分布在食品中。另外，许多菌株是嗜冷菌，是导致新鲜冷冻食品腐败的重要细菌。有时腐败能产生水溶性蓝绿色素。Pseudomonas：Thesegram-negativerodsconstitutethelargestgenusofbacteriathatexistinfreshfoods.Theyaretypicalofsoilandwaterbacteriaandarewidelydistributedamongfoods.Theyare,byfar,themostimportantgroupofbacteriathatbringaboutthespoilageofrefrigeratedfreshfoodssincemanyspeciesandstrainsarepsychrotrophic.Somearenotablebytheirproductionofwater-soluble,blue-greenpigments.产碱杆菌属：革兰氏阴性棒状杆菌，但菌体着色时有时也显现革兰氏阳性反应，周身鞭毛，无芽孢，严格好气，化能有机营养型，大多营养简单。不能发酵糖类，但能产碱（特别是在石芯乳中）。不产色素，分布在各种腐烂物质中，并大量存在于原乳、食用家禽制品以及排泄物中。Alcaligenes:Althoughgramnegative,theseorganismssometimesstaingrampositive.Theyarerodsthatdonot,asthegenericnamesuggested,Nfermentsugarsbutinsteadproducealkalinereactionsespeciallyinlitmusmilk.Nonpigmented,theyarewidelydistribu-tedinnatureindecomposingmatterofalltypes.Rawmilk,poultryproduct,andfecalmatterarecommonsource.沙雷氏菌属:革兰氏阴性、杆状、好氧，能分解蛋白质，有时能产生红色素，而不产色素的菌株则比较少见。液化沙雷氏菌是与食物中毒相关的最常见的菌株，能够引起冷冻蔬菜以及肉类制品的腐败。Serratia：Thesegram-negativerodsbelongtothefamilyEnerobacteriaceaeareaerobicandproteolytic,andtheygenerallyproduceredpigmentsonculturemediaandincertainfoods,althoughnonpigmentedstrainsarenotuncommon.S.liquefaciensisthemostprevalentofthefoodbornspecies;itcausesthespoilageofrefrigeratedvegetableandmeatsproducts.弧菌属:革兰氏阴性，直形或弯曲形杆菌，极生鞭毛，兼厌气性，通常需要一定浓度的盐，可污染咸鱼咸肉，有几株菌株能够引起人体肠胃疾病或其他疾病。Vibrio:Theyaregram-negativestraightorcurvedrods。Severalspeciescausegastroenteritisandotherhumanillness.志贺氏菌属:杆状、不运动、无芽孢、无荚膜、革兰氏阴性，不能利用柠檬酸盐，能产酸但不产气。该属所有菌株都可存在于人体肠道中。Shigella：Allmembersofthisgenusarepresumedtobeenteropathogens.气单胞菌属：典型的水生革兰氏阴性棒状杆菌，极生鞭毛，兼厌气性。能发酵糖类产生大量气体。通常出现在鱼体中。Aeromonas:Thesearetypicallyaquaticgram-negativerods.Asthegenericnamesuggest,theyproducecopiousquantitiesofgasfromthosesugarfermented.弯曲杆菌属：革兰氏阴性，弯曲成螺旋杆状，曾归入弧菌属，厌氧或微好氧。Campylobacter:Thesegramnegative,spirallycurvedrodswereformerlyclassifiedasvibrios.Theyaremicroaerophilictoanaero