一属罕见的细菌——多孢子菌属

POLYSPOROBACTERIUM——A UNIQUE GENUS OF BACTERIA

我们发现并鉴定了一属新的细菌,其主要特征是能够从无菌丝的营养细胞直接转变为孢囊,产生大量孢子进行繁殖,并以甲烷作为唯一碳源与能源而生长。它同其它已知细菌有较大的差别,因而暂建立一个新的属:多孢子菌属 Polysporobacterium。模式种为沙石多孢子菌Polysporobacterium arenarium。它们在分类学上的位置将另行讨论。

A new genus of bacteria with uniqueproperties is reported.The most remark-able feature of this new microorganism isits mode of reproduction.In addition tobinary fission,the vegetable cells have beenfound also to produce directly a largenumber of sporangiospores.These sporan-giospores may,under appropriate culturalconditions,turn into zoospores.This newbacterium utilizes methane as its sole car-bon and energy source.It is,therefore,entirely different from any other group ofbacteria so far known.It is considered thatit belongs to a new genus and the genericname Polysporobacterium is proposed.The type species is Polysporobacteriumarenarium.Polyaporobacterium gen.nov.Cells are rods,occurring single,inpairs and sometimes in short chains.Gramnegative.Young cells motile with polarmonotrichous flagellum.In old culturecells occurred spherical.Cells possessed acomplex internal membrane system oftype I.Colonies brown,brownish-yellow,yellow or colorless.The most remarkablefeature of this microorganism is its modeof reproduction.In addition to binaryfission,the vegetable cells have been foundalso to produce directly a large numberof sporangiospores.Methane is used assole carbon and energy source.No growthoccurs on nutrient agar.Nitrate,am-monium ion and molecular nitrogen canbe used as sources of nitrogen.The G +C content of DNA of type species is 57.5moles % （Tm）.Aerobic.The type species is Polysporobacteriumarenarium.Polysporobacterium arenariumsp.nov.In shake-culture with mineral saltscontaining combined nitrogen,cells repro-duced with binary fission,occurring single,in pairs and sometimes in short chains（Pl.I,fig.5）.They are about 1.5—3.0×2.0—5.0 μm in size.Gram negative.Youngcells motile with monotrichous flagellum.In old culture cells are short,sphericaland,eventually,become resting cysts em-bedded in extracellular slime （Pl.I,fig.6）.The microorganism possessed a well-defined membraneous system of type I（Pl.Ⅰ,fig.9—12）.The G + C contentof DNA is 57.5 moles % （Tm）.Colonies brown,brownish-yellow oryellow in color.The well-developed co-lonies have deep wrinkled or vorticalwrinkled surface and palisade-shaped atold stage （Pl.Ⅰ,fig.1—4）.The color ofcolonies appears as spots.In agar mediumwithout combined nitrogen colonies arecolorless or slightly brownish-yellow.Cellsare capsulated （Pl.Ⅰ,fig.7）.On medium without combined nit-rogen or with suitable conditions,thevegetable cells transform into sporangiaafter certain and form a large number ofsporangiospores （Pl.Ⅱ,fig.1—3）.Thesporangiospores has wrinkled thin mem- brane （Pl.Ⅱ,fig.4）.When free wateris present,these sporangiospores lose thinmembrane and become zoospores spreadingto all directions （Pl.-Ⅱ,fig.5—7）.Inthe absence of water,sporangiospores arenon motile and occur as a "great" massof cells in the place of sporangium （Pl.Ⅱ,fig.8—9）.Both sporangiospores andzoospores can develop into vegetable cellsas mother-cells.The organism utilizes methane as solesource of carbon and energy.No growthoccurs on nutrient agar,methanol,xylose,fructose,glucose,sucrose,galactose.Itgrows well on media with NO3-,NH4+and N2 as sources of nitrogen.It is aerobicand grows at 40℃ and pH 6.8—7.0.Itwas isolated from sample of sand and grit.