Harnessing seaweed-associated marine Streptomyces sp. OSs-1 for nanotechnology-driven cost-effective enzyme...

Protease and amylase are industrially significant enzymes whose production must balance purity, productivity, and cost-efficiency. This study investigates the isolation, phenotypic and genetic characterization, growth kinetics, immobilization, and statistical optimization of enzyme co-production by Streptomyces sp. OSs-1, associated with the red seaweed Sarconema sp., isolated from the intertidal zone of Okha, Gujarat. The red alga Sarconema is industrially valuable due to its carrageenan production and interesting association with bioactive microbial communities. A Plackett-Burman design identified five significant variables influencing enzyme production, which were further optimized using RSM with a Box-Behnken design. ANOVA confirmed that NaCl concentration and incubation time were the most critical factors (p < 0.05). Under optimal conditions (3 % NaCl, 5-day incubation), maximum amylase (375.91 ± 23.70 U/mL) and protease (294.89 ± 15.07 U/mL) production was achieved. Graphical tools, including Pareto charts and interaction plots, validated these outcomes. To reduce production costs, agricultural wastes were explored as alternative substrates. Sorghum straw supported the highest enzyme co-production (amylase: 206.87 ± 7.07 U/mL, protease: 315.08 ± 14.14 U/mL), along with the highest cell mass (0.0043 g/mL) and specific growth rate (0.0062 h^-1). Enzyme immobilization using sodium alginate, zinc oxide nanoparticles, and hydroxyapatite enhanced enzyme stability and reusability. The highest immobilized activities were obtained with sodium alginate+ 5 % glutaraldehyde for amylase (316.39 U/g), and with sodium alginate+zinc oxide nanoparticles+hydroxyapatite+ 10 % glutaraldehyde for protease (298.65 U/g). Immobilized enzymes showed improved thermal and pH stability. This study demonstrates that incorporating agricultural waste substrates, advanced immobilization techniques, and nanotechnology offers a cost-effective and scalable solution for industrial enzyme production from seaweed-associated Streptomyces sp. OSs-1.