Abstract:

 Inordertounderstandtheformationmechanismofcarbonatemineralsinducedbymicrobes,cultureexperimentswitha durationof165dayswereperformedunderthemediationofstrainGW-Misolatedfromsoil.MineralspeciesweredeterminedbyX-ray diffraction,andthemorphologiesofprecipitatedcarbonateswereobservedusingscanningelectronmicroscopy.Theresultsshowedthat the carbonate minerals (calcite and monohydrocalcite) induced by strain GW-M featured various morphologies, mainly spherical morphology.Incontrast,morphologiesofcarbonatemineralsformedintheasepticexperimentswererelativelysimple.Threeways mightleadtotheformationofsphericalmineralsundertheactionofstrainGW-M.(1)Thefirstwaywassingledumbbell-shaped mineralswithfinecrystalsgatheredfasteronbothendsthanthemiddlepartofthedumbbell,changingdumbbell-shapedmineralsinto sphericalones.(2)Thesecondwaywastwocrosseddumbbell-shapedmineralswithfinecrystalsgatheredfasteronbothendsthanthe middlepartofthetwodumbbells,resultinginsphericalminerals.(3)Thefinalwaywasthreecrosseddumbbell-shapedmineralswith finecrystalsgatheredfasteronbothendsthanthemiddlepartofthethreedumbbells,eventuallyevolvingintosphericalminerals.

Key words: Citrobactersp.;carbonateminerals;dumbbell-likemorphology;sphericalmorphology