Preparation and evaluation of Magnetospirillum gryphiswaldense MSR-1 bioinoculant on the growth and productivity of Vigna radiata (L.) R. Wilczek.

Recently, there has been a growing interest in the application of beneficial microorganisms to enhance crop performance. Magnetospirillum gryphiswaldense (MSR-1) are spiral-shaped, gram-negative bacteria that exhibit magnetotaxis with the help of magnetosomes (iron oxide or iron sulphide). They have exhibited biomedical and environmental applications; however, the agricultural utilization of these strains is yet to be explored. This study investigates the nitrogen fixation, iron supplementation, and plant growth promotion (PGP) activity of MSR-1 on Vigna radiata (Green gram). Firstly, agriculturally important genes including nif (360 bp), fur (480 bp), and feoB (675 bp) were identified in MSR-1. Further, the strain was used to produce the Magnetospirillum Liquid Biofertilizer (MLB) and analyzed using GC-MS and LC-HRMS to identify beneficial compounds for agriculture. The findings indicated the presence of biostimulant compounds including proline, indole-3-acetic acid, koninginin, and glutamate. Furthermore, different dilutions (20%, 40%, 60%, 80%, and 100%) of MLB were supplemented to V.radiata to explore its nitrogen-fixing capacity, iron enhancement effects, plant growth and yield. Plants treated with 20% MLB exhibited a significant increase in plant length (85.6%), seed weight (74.5%), total chlorophyll content (58.3%), protein (95.91%), leaf nitrogen content (71.72%) compared to the control group treated with distilled water. Under iron deficiency conditions, 60% MLB improved the plant length (70.38%), seed weight (66.6%), total chlorophyll (84.16%), protein (66.19%), iron content of leaves (80.79%) compared to the control group. The findings indicate that MSR-1 enhances plant productivity and it can be used as a source of iron fertilizer for addressing iron deficiency in plants.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-025-04206-8.