Encapsulation of Rhodopseudomonas palustris KTSSR54 using beads from alginate/starch blends

Alginate beads are a promising carrier for biofertilizer delivery, but still possess drawbacks of low mechanical strength and bead shrinkage that result in poor appearance and inadequate cell protection. Blending alginate with starch was proposed as a solution to these problems, and here alginate hydrogels were prepared using a 2% (w/v) alginate dispersion blended with varying contents of gelatinized starch (0–5% w/v). The interaction produced a viscosity synergism that increased the complexity of the matrix network in the alginate/starch blends, producing a more suitable matrix for cell entrapment. Hydrogen bonding between alginate and starch influenced the viscosity of the various solutions in a way that was consistent with the FTIR spectra. The starch content also helped beads retain their spherical shape after drying. The starch supported the entrapment of bacterial cells (plant growth‐promoting bacterium Rhodopseudomonas palustris KTSSR54 as biofertilizer) in the matrix, which reduced cell loss. The highest entrapment efficiency of 70.83% was obtained at 4% (w/v) starch, while the entrapment efficiency of control beads was 50.56%. Overall, the appropriate content of starch mixed with alginate is conducive to changes in the morphology of microcapsules and increases in the amount of biological encapsulation. The main limitation of alginate beads is the loss of cells due to its loose matrix. Mixing appropriate amount of starch at 4% (w/v) into 2% (w/v) alginate produced a remarkable improvement of complexity matrix as the interaction of both biopolymers to produce viscosity synergism through hydrogen bonding. Gelatinized starch also acted as a structural support to reduce voids for providing spherical beads. This led to significantly increase in cell entrapment efficiency for biofertilizer delivery.