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3～4種zhong菌jun落luo類lei型xing
，而er在zai黃huang豆dou粉fen培pei養yang基ji上shang僅jin出chu現xian兩liang種zhong菌jun落luo類lei型xing。在zai開kai始shi菌jun種zhong選xuan育yu工gong作zuo時shi，要yao研yan究jiu單dan菌jun落luo的de分fen離li培pei養yang基ji，找zhao出chu能neng呈cheng現xian較jiao多duo菌jun落luo類lei型xing的de分fen離li培pei養yang基ji。菌jun落luo類lei型xing和he發fa酵jiao產chan量liang之zhi間jian存cun在zai著zhe某mou種zhong程cheng度du的de相xiang關guan性xing。在zai選xuan種zhong實shi踐jian中zhong
，人ren們men經jing過guo對dui菌jun落luo形xing態tai的de考kao察cha，有you意yi識shi地di丟diu棄qi一yi些xie被bei認ren為wei是shi低di產chan的de菌jun落luo，挑tiao選xuan那na些xie可ke能neng是shi高gao產chan的de菌jun落luo。

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。