Exploring the potential of Aloe vera as a carrier for developing a novel cyanobacterial formulation

Abstract Cyanobacteria are commonly deployed as inoculants to enrich the nutrient status of soil and stimulate plant growth. For large scale application, easy to use formulations which can remain functionally viable during storage are required. In this context, the nutritive qualities of Aloe vera gel was explored to develop an aqueous formulation (AE), which was supplemented with a beneficial cyanobacterium Anabaena laxa (RPAN8), thereafter, referred to as AEC. Different inocula levels of 1, 2 and 5% were used to amend the graded dilutions (Pure, 1:1, 1:5, 1:10) of AE. Time course observations showed that all the dilutions supported cyanobacterial growth (as evident from increase in chlorophyll content) upto 70 days. Available phosphorus content of AE samples declined (28%) following cyanobacterial growth, indicating P utilization by the cyanobacterium. At all levels of inocula, growth was found to be higher (1.4–2 folds on 35th day of storage) in 1:10 dilution, as compared to lower dilutions or pure samples. Microscopy and PCR based analyses confirmed the presence of the inoculated cyanobacterium in the Aloe vera formulations (AEC). Most importantly, these formulations exhibited plant growth promoting trait, fungicidal activity and stimulated the germination of wheat and mustard seeds. This represents a novel approach exploring the useful qualities of Aloe vera to design a carrier for an agriculturally important cyanobacterium Anabaena laxa. The effective maintenance of the functional attributes of the cyanobacterium highlights its promise and the need for further refinement as an environment-friendly and phyto-beneficial option for farmers and entrepreneurs.