Microencapsulation of Bacillus subtilis by spray-drying using starch hydrolysates with different dextrose equivalent...

Area of Science:

• Agricultural Microbiology
• Biotechnology
• Materials Science

Background:

• Sustainable agriculture demands enhanced microbial biofertilizer efficacy.
• Maintaining viability of plant growth-promoting microorganisms like Bacillus subtilis during storage and application is critical.
• Microencapsulation offers a potential solution to protect beneficial bacteria.

Purpose of the Study:

• To evaluate starch hydrolysates with varying dextrose equivalent (DE) values as wall materials for spray-drying Bacillus subtilis.
• To assess the impact of DE values on microcapsule properties, cell protection, and stability.
• To determine the potential of encapsulated B. subtilis as a superior biofertilizer.

Main Methods:

• Spray-drying encapsulation of Bacillus subtilis using starch hydrolysates with DE-8, DE-18, and DE-38.
• Characterization of microcapsule morphology and particle size.
• Assessment of encapsulation efficiency.
• Evaluation of cell viability under salinity, acidic pH, UV exposure, thermal stress, and storage conditions.

Main Results:

• High encapsulation efficiency (approx. 80%) achieved for all formulations.
• Higher DE values (DE-18, DE-38) resulted in smoother, smaller, and more homogeneous microparticles.
• Microcapsules provided significant protection against salinity, acidic pH, and UV stress (DE-18 superior).
• Enhanced thermal stability (over 95% viability at 50°C for 72h with DE-18 and DE-38) and storage longevity were observed.

Conclusions:

• Starch hydrolysates, particularly those with higher DE values, are effective wall materials for B. subtilis microencapsulation.
• Spray-dried microencapsulation significantly improves the viability and stability of B. subtilis biofertilizers.
• This technology holds promise for enhancing the performance and application of microbial inoculants in sustainable agriculture.