Mass production of arbuscular mycorrhizal fungi on soybean mill waste inoculated with Burkholderia arboris and planted to sorghum

Abstract Arbuscular mycorrhizal (AM) fungi are being used as a new generation biofertilizers to increase plant growth by improving plant nutrition and bio-protection. However, because of its obligatory nature of plant host, large-scale multiplication of AM propagules is challenging, which limits the scope of its applicability. The purpose of current study was to evaluate Burkholderia arboris’s ability to increase AM production in soybean mill waste planted with sorghum as host plant. The study was conducted in a completely randomized design comprising of four inoculation treatments ( B. arboris , AM fungi, B. arboris plus AM fungi, and a no inoculum as control) under sterilized and unsterilized conditions. AM production was investigated microscopically through spore density and root colonization, as well as biochemically using AM-specific lipid biomarker, 16:1w5cis derived from neutral lipid fatty acid (NLFA) and phospholipid fatty acid (PLFA) fractions from both soil and roots. Integrating B. arboris with AM fungi in organic amended pots was found to increase AM fungal production by 62.16 spores/g soil and root colonization by 80.85%. Biochemical parameters also increased with B. arboris inoculation: 5.49 nmol PLFA/g soil and 692.68 nmol PLFA/g root and 36.72 nmol NLFA/g soil and 3147.57 nmol NLFA/g root. Additionally, when compared to other combinations, co-inoculation increased glomalin related soil protein and root biomass. The principal component analysis (PCA) further explained the higher contribution of B. arboris to AM fungi multiplication under unsterilized conditions. In conclusion, adding B. arboris to organic potting mixes could be a promising and cost-effective approach of increasing AM inoculum density for commercial production.