Isolating Arthrobacter Species With A Strong Ability To Degrade Cellulose And To Produce Potential Biofuel

Members of Arthrobacter genus that belong to Actinobacter phylum were first discovered by Conn and Dimmick in 1947.Various strains of genus Arthrobacter can generate energy by decomposition of different natural or man-produced organic substances available in their living environment.The aim of our research was to isolate Arthrobacter species having a strong ability to degrade cellulose and produce potential biofuels.We collected six soil samples designated SLP1,SLP2,SLP3,SLP4,SLP8,and SLP9 from different areas of the Shule river valley in Gansu province(China).A total of 57 strains were isolated in CMC-Agar medium from the soil samples.Based on morphological characteristics 32 strains were identified to belong to arthrobacter species with rod-coccus,V-shape and no–motile morphology.Qualitative assay was used to evaluate cellulose degradation ability for each of these isolated 32 strains.Of those 6 strains(SLP4(10e-2)b,SLP8(10e-3)a,SLP9(10e-4)c,SLP2(10e-4)c,SLP1(10e-2)a,and SLP4(10e-4)c)grew well on CMC-Agar medium,with colony diameters ranging from 3-4 mm.Quantitative assay of biofuel production showed that only one strain SLP1(10e-2)a had a strong ability to produce biofuels.16 SrRNA gene sequencing identified the isolated SLP1(10e-2)a as Athrobacter nitroguajacolicus strain IHBB9963.The chemical properties of the extracted biofuels were analysed by gas chromatography and mass spectrometry.Among 41 identified short-chain carbon compounds five were eluted at highest peak concentrations with carbon numbers ranged from C16 to C22 which belonging to alkanes,alkenes,and alcohols groups.NTG mutagen was used to mutate the isolate IHBB9963 to enhance its biofuel productivity.Of the 95 mutant strains isolated four mutant strains that could produce higher content of biofuels than that of the parent strain IHBB9963 was obtained.To assess the main factors that influenced the biofuel productivity,these four mutant strains were cultured in LB-Agar and Soluble Starch-Agar medium.The results obtained showed that in SS-Agar medium mutant strain-40 produced more biofuel at the 96 th hour during incubation,mutant strain-46 at 168 th,and mutant strain-50 168 th,whereas,mutant strain-82 showed a poor productivity for all culture duration.In LB-Agar medium,only mutant 82-strain showed a significant production at 168 th of incubation.This indicates that each mutant strain has its own optimum time and appropriate culture medium for highest biofuel production.