Zair Shakirov¹, Iskandar Yakubov², Khursheda Khamidova¹, Saidakhon Zakiryaeva¹, Nodira Azimova¹, Sardarkhodja Kurganov³, Cheng Gao⁴, Husniddin Karimov¹*
1Institute of Microbiology, Academy of Sciences of the Republic of Uzbekistan, Tashkent, Uzbekistan
2National University of Uzbekistan, Tashkent, Uzbekistan
3Republican Scientific Specialized Center of Allergology, Tashkent, Uzbekistan
4State Key Laboratory of Microbial Diversity and Innovative Utilization, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
*Corresponding author’s email: husniddin263@gmail.com
Received: 25 January 2026 / Revised: 04 May 2026 / Accepted: 20 May 2026 / Published Online: 12 June 2026
Abstract
Extracellular acid phosphatase plays a key role in the mobilization of organic phosphorus in soil ecosystems. In this study, acid phosphatase produced by Trichoderma asperellum Uz-A4 was isolated, purified and biochemically characterized. Maximum enzyme activity (1534 µM min⁻¹ mg⁻¹) was observed on the sixth day of cultivation in Czapek broth. Zymogram analysis revealed two extracellular acid phosphatase isoforms with molecular masses of approximately 175 and 115 kDa. The dominant isoform (ACP1) was purified by ammonium sulfate precipitation followed by DEAE–TSK ion-exchange and Phenyl–Sepharose hydrophobic interaction chromatography. SDS–PAGE analysis showed that ACP1 is a homodimer composed of two identical subunits of 85 kDa. The enzyme exhibited optimal activity at pH 5.0 and 50 °C and retained high activity after incubation at 60 °C for 1 h, indicating pronounced thermostability. Zn²⁺ and Mn²⁺ ions significantly inhibited enzyme activity, whereas Ca²⁺, Co²⁺, Mg²⁺, EDTA and reducing agents had no substantial effect. The biochemical properties of ACP1 highlight the potential of T. asperellum Uz-A4 to contribute to organic phosphorus mineralization and to improve phosphorus availability and soil fertility under sustainable agricultural systems.
Keywords: Acid phosphatase, Phosphate-solubilizing microorganisms, Phosphorus mobilization, Soil fertility, Trichoderma spp.
