Professor
Janardan Lamichhane
Department of Biotechnology. School of Science, Kathmandu University, Nepal
Revelation of Achromobacter spanius B5 as Free-Living Nitrogen Fixer from Bamboo Rhizosphere
Govinda Pathak, Gyanu Raj Pandey, Sandip Ghimire, Khusbu Raut, Parash Mani Timilsina, Bishnu Maya KC, Janardan Lamichhane
Free-living diazotrophs critically enhance nitrogen (N) bioavailability in ecosystems, supporting plant productivity while reducing reliance on synthetic fertilizers. Free-living diazotrophs from the bamboo rhizosphere using nitrogen-free bromothymol blue (NFB) medium were isolated to harness this potential in underexplored niches. Isolate B5 exhibited robust nitrogen-fixing activity within 24 hours, achieving a nitrogen-fixing index of 7.36 ± 0.78 by day 5. Quantitative spectrophotometric analysis (Nesslerization, 425 nm) confirmed escalating ammonium production: 5.59 ± 2.99 ppm (24 h), 33.05 ± 7.42 ppm (48 h), and 76.33 ± 2.81 ppm (72 h). The strain exhibited moderate tolerance to abiotic stresses (temperature, pH, salinity, drought) in OD600-based growth assays. Phylogenetic analysis based on 16S rRNA gene sequencing, alongside morphological and physiological characterization, identified B5 as Achromobacter spanius. This bamboo rhizosphere isolate, A. spanius B5 (reported for first time in bamboo rhizosphere) exhibited significant free-living N2-fixation capacity, positioning it as a potent biofertilizer candidate that enables sustainable, chemical-fertilizer-independent enhancement of plant-available N. Our findings demonstrate high N2-fixation activity in the bamboo rhizosphere and highlight A. spanius B5 as a novel microbial resource for advancing eco-friendly agriculture through native diazotroph utilization.
Keywords: Achromobacter spanius, rhizosphere, non-symbiotic nitrogen-fixing bacteria, bio-inoculum, and sustainable agriculture.
Biography of Janardan Lamichhane
Prof. Janardan Lamichhane has completed his PhD degree from the republic of Korea in 2006 in Biochemistry and worked in genetic engineering in bacterial genome. Presently, he is the director of Organic farming and Natural product Research Center (ONRC) at Kathmandu University. He also served as the Dean of School of Science. He has published more than 90 papers in genetics, Medicinal plants, bacterial analysis and Agriculture related fields.
Details:
Full Name: Janardan Lamichhane
Contact number: +977 9851178913
Email: ljanardan@ku.edu.np , ljanardan@gmail.com
ORCID: 0000-0001-8020-9143