The First Report of Indigenous Free-Living Diazotroph Kosakonia sacchari Isolated from Himalayan Alder-Based Shifting Cultivation System in Nagaland, India

Abstract

A study was carried out to explore soil bacterial diversity associated with Himalayan Alder (Alnus nepalensis)-based shifting cultivation system in Khonoma Village, Nagaland. This agricultural system is well known for its traditional and sustainable form of shifting cultivation and natural biodiversity conservation in the Eastern Himalayan region of India. Surface soil samples (0–30 cm) were collected from alder-based crop fields in Khonoma, Nagaland, and brought to the laboratory for soil nutrient analysis and isolation of culturable bacteria. Standard methodologies were followed for soil nutrient and bacterial diversity analysis. Isolated bacteria were identified using 16S rDNA spacer sequence analysis. BLAST and phylogenetic analysis of molecular sequences identified a unique bacterial isolate in the soil. 16S rDNA partial sequencing of this bacterial strain showed 99% similarity with Kosakonia sacchari–type strain SP1T which has been named for its association with sugarcane. K. sacchari KhAn is a free-living, aerobic, gram-negative, non-spore-forming, and motile rod-shaped bacterium. This bacterial strain holds diazotrophic potential as it was able to grow in nitrogen-free medium and positive for nifH amplification. Furthermore, it showed positive test for ammonia production in peptone water. The soil under alder-based farming system was rich in organic carbon (3.60 ± 0.17%), available nitrogen (536.67 ± 9.28 kg ha−1), available phosphorous (77.35 ± 4.19 kg ha−1), and exchangeable potassium 127.88 ± 10.62 kg ha−1. The existing literature revealed that K. sacchari has not been reported from India until now; therefore, this is the first novel report from India. This contribution represents Eastern Himalaya, a Biodiversity hotspot of the country.