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Subject: Agricultural Microbiology × End date: 2009 × Start date: 2009 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Studies on endorhizosphere bacteria of Nothapodytes nimmoniana Grahm and their influence on plant growth and camptothecin content
    (UAS Dharwad, 2009) C.R.Patil; A.R.Alagawadi
    Microbiological explorations were made to isolate endorhizosphere bacteria from the roots of Nothapodytes nimmoniana a medicinal herb distributed in Central Western Ghats of India. A total of 92 isolates were obtained on six culture media from 23 root samples. All isolates were characterized based on their biochemical properties and tentatively 70 isolates could be identified (17 Azotobacter , 18 Pseudomonas, 10 Azomonas, 13 Bacillus , 5 Beijerinckia, 4 Acetobacter and 3 Acidomonas). The functional and molecular diversity was studied. Sixteen isolates produced about moderate to high quantities of IAA.. Two isolates produced significantly higher quantity of GA. Twelve isolates with low levels of IAA production however produced moderate to high levels of GA. Twenty isolates showed ability to solubilize TCP. Twenty two isolates fixed atmospheric nitrogen among which 20 excreted ammonia into medium. Sixteen isolates showed antagonistic activity against one or more of the five plant pathogens tested. The isolates were also examined for MEP pathway and only 26 isolates contained dxs and dxr genes of this pathway. In 18 of these isolates the pathway was operational. Two isolates also produced tryptamine an important intermediate of camptothecin biosynthesis. One isolate (SRS-15) produced CPT like compound in Czepak Dox (CD) medium amended with the two intermediates of CPT biosynthesis. An attempt was made to bioprospect CPT production from SRS-15 using CD medium amended with 300 μg ml-1 each with IPP, DMAPP. Growth and CPT content of N. nimmoniana in response to inoculation with selected endorhizosphere bacteria and proven biofertilizers at nursery stage was studied involving three independent experiments. Biomass and CPT content of plants increased due to inoculation with either endorhizosphere bacteria (SRS-6) or biofertilizers (Azotobacter and P. striata). It was found that inoculation of SRS-35 in sterile, SRS-6 and Azotobacter + P. striata in un-sterile growth medium enhanced growth and CPT content of N. nimmoniana seedlings.