① 一yi個ge菌jun種zhong不bu是shi純chun的de群qun體ti，而er是shi由you一yi些xie變bian異yi株zhu混hun合he組zu成cheng，這zhe些xie變bian異yi株zhu所suo占zhan的de比bi例li決jue定ding該gai菌jun種zhong的de特te性xing。一yi個ge由you單dan菌jun落luo發fa育yu而er來lai的de菌jun種zhong在zai固gu體ti培pei養yang基ji上shang分fen離li
，可ke以yi長chang出chu許xu多duo種zhong形xing態tai培pei養yang特te征zheng的de菌jun落luo。這zhe些xie不bu同tong的de菌jun落luo類lei型xing在zai代dai謝xie和he生sheng長chang繁fan殖zhi速su度du等deng方fang麵mian有you一yi定ding差cha異yi。培pei養yang條tiao件jian可ke以yi影ying響xiang各ge變bian異yi株zhu在zai培pei養yang物wu中zhong的de比bi例li而er改gai變bian該gai菌jun種zhong的de特te性xing。同tong一yi個ge菌jun種zhong的de單dan孢bao子zi分fen離li在zai不bu同tong的de培pei養yang基ji上shang，所suo生sheng長chang出chu的de單dan菌jun落luo，其qi形xing態tai培pei養yang特te征zheng有you顯xian著zhu差cha異yi

，各ge種zhong類lei型xing菌jun落luo所suo占zhan的de比bi例li也ye不bu同tong。如ru灰hui色se鏈lian黴mei菌jun(Streptomyces griseus)在豌豆瓊脂培養基上，單孢子分離呈現出3～4zhongjunluoleixing，erzaihuangdoufenpeiyangjishangjinchuxianliangzhongjunluoleixing。zaikaishijunzhongxuanyugongzuoshi，yaoyanjiudanjunluodefenlipeiyangji
，zhaochunengchengxianjiaoduojunluoleixingdefenlipeiyangji。junluoleixinghefajiaochanliangzhijiancunzaizhemouzhongchengdudexiangguanxing。zaixuanzhongshijianzhong，renmenjingguoduijunluoxingtaidekaocha，youyishididiuqiyixiebeirenweishidichandejunluo
，tiaoxuannaxiekenengshigaochandejunluo。

② junzhongpeiyangjiketongguoyingxiangjunzhongdeshenglizhuangkuangeryingxiangfajiaochanliang。junzhongpeiyangjiyingyangguoyufengfubuliyubaozixingcheng，yineryingxiangfajiao。junzhongpeiyangjiyingyangpinfayetongyangbuliyufajiao。yinweijunzhongzaiyingyangpinfadepeiyangjizhongduocichuandai，huishijuntixibaoneiquefamouxieshengchangyinziershuailaoshenzhisiwang。yinci，ziranxuanyuhuojunzhongpeiyangsuoyongdepeiyangjiyingxuanzejuyoujunzhongchuandaihoushengchannenglixiajiangbumingxian、菌體不易衰老和自溶的正常形態菌落
、孢子豐富的培養基。

③ zaimouxiepeiyangtiaojianxia，juntidemouxiejiyinchuyuhuohuazhuangtaihuozuezhuangtai，ershijunzhongdeshenglizhuangtaigaibian。zhezhonggaibiankenengyileisiyushenglixingchiyanhuoxibaofenhuadejizhibaochijiaochangyiduanshijian。

youyujunzhongdeshuaituijianghuiyinqifajiaoguochengdechanliangjijuxiajiang
，yidanfashengjunzhongshuaitui，jiubixucaiquyouxiaodeyufanghefangzhicuoshi
，fangzhijunzhongdeyouliangxingzhuangfashengtuihua。tongshiruofaxianmouxieyouliangxingzhuangtuihua，yingjishijinxingfenlichunhua，shishengchanjunzhongbaochiwendingdeyouliangtexing。fangzhijunzhongshuaituidecuoshizhuyaoyoujunzhongdefuzhuang、提供良好的環境條件
、定期純化菌種

、防止自身突變等各個方麵。