Fungal rock phosphate solubilization using sugarcane bagasse.

Area of Science:

• Agricultural Microbiology
• Biotechnology
• Soil Science

Background:

• Rock phosphate (RP) is a key source of phosphorus (P), an essential plant nutrient.
• Efficient solubilization of RP is crucial for sustainable agriculture and reducing reliance on synthetic fertilizers.
• Solid-state fermentation (SSF) offers a promising approach for microbial solubilization of sparingly soluble minerals like RP.

Purpose of the Study:

• To evaluate the efficacy of different fungal species in solubilizing Brazilian rock phosphate (Araxá and Catalão) using solid-state fermentation (SSF).
• To determine the optimal concentrations of rock phosphate, sucrose, and ammonium sulfate for enhanced phosphorus solubilization.
• To identify the most effective fungal strain and substrate combination for producing a low-cost biofertilizer.

Main Methods:

• Solid-state fermentation (SSF) using sugarcane bagasse as a substrate.
• Evaluation of four fungal strains: Aspergillus niger, Penicillium canescens, Eupenicillium ludwigii, and Penicillium islandicum.
• Application of a 2(3) + 1 factorial design to assess the effects of rock phosphate, sucrose, and ammonium sulfate concentrations.

Main Results:

• Higher rock phosphate doses generally led to increased phosphorus solubilization.
• Sugarcane bagasse provided sufficient carbon and nitrogen, reducing the need for sucrose supplementation.
• Aspergillus niger demonstrated superior phosphorus solubilization capacity, outperforming other fungi and not requiring sucrose or ammonium sulfate.
• Optimal conditions with Aspergillus niger achieved a maximal P yield of approximately 60% at a lower RP dose (3 g L(-1)).

Conclusions:

• Solid-state fermentation with Aspergillus niger and sugarcane bagasse is an effective and low-cost method for producing phosphorus-rich biofertilizers.
• Sugarcane bagasse serves as an excellent substrate, supplying necessary nutrients for fungal metabolism and rock phosphate solubilization.
• Aspergillus niger is a highly promising microorganism for the bio-solubilization of rock phosphate, offering a sustainable alternative to conventional fertilizers.