en Fish processing Fish processing پژوهشي Orginal research papers <div style="text-align: justify;"><strong><span lang="TR" style="font-size:11.5pt"><span style="font-family:&quot;Calibri&quot;,sans-serif"><span style="color:black"><span style="font-weight:normal">Fish processing generates substantial amounts of organic waste, particularly from high-value species like sturgeon. Transforming these nutrient-rich wastes into value-added products, such as biosilage and amino acid fertilizers, offers an environmentally friendly solution that aligns with the principles of a circular bioeconomy. This study aimed to produce biosilage from sturgeon waste through microbial fermentation and to evaluate its potential for amino acid fertilizer production. Initially, biosilage was prepared and subjected to quality control through assessments of proximate composition and microbial indices. Molecular identification of the dominant fermentative bacteria using 16S rRNA sequencing revealed the presence of <i>Bacillus cereus</i> (99.5% similarity; Accession No. KP940382.1), as well as lactic acid bacteria, including <i>Lactobacillus plantarum, L. acidophilus, and L. pentosus</i>.&nbsp;The biosilage demonstrated significantly higher levels of protein (67.7%), lipid (14.06%), and ash (11.26%), along with lower moisture content (6.98%) compared to raw waste (<i>p</i><0.05). Microbial analysis confirmed the safety of the biosilage, showing high levels of lactic acid bacteria (6.48 log CFU/g) and the absence of <i>Escherichia coli</i> and <i>Salmonella typhimurium</i>. After quality control, an amino acid fertilizer was produced from the biosilage. The amino acid profile revealed total and free amino acid contents of 14.02% and 8.08%, respectively, with glutamic acid&nbsp; and leucine being the most abundant. Additionally, elemental analysis showed a balanced nutrient content, including total nitrogen (3.56%), phosphorus (0.81%), potassium (0.34%), and organic matter (17.92%). In conclusion, the stepwise conversion of sturgeon waste into biosilage and amino acid fertilizer represents eco-friendly strategy for waste valorization.</span></span></span></span></strong></div> Biosilage, Amino acid fertilizer, Sturgeon waste, Quality and microbial indices, Proximate composition, Amino acid profile 509 524 http://jifro.ir/browse.php?a_code=A-10-5645-1&slc_lang=en&sid=1 M. Mahmoudi Joybari mahmoudimbin@gmail.com 100319475328460058852 100319475328460058852 No Department of Biology, Faculty of Basic Sciences, Islamic Azad University, Ghaemshahr Branch, Ghaemshahr, Iran A.A. Dehpour dehpour@gmail.com 100319475328460058853 100319475328460058853 Yes Department of Biology, Faculty of Basic Sciences, Islamic Azad University, Ghaemshahr Branch, Ghaemshahr, Iran R. Safari safari1351@gmial.com 100319475328460058854 100319475328460058854 No Caspian Sea Ecology Research Institute, Fisheries Science Research Institute, Agricultural Education and Extension Research Organization, Sari, Iran F. Farokhi farzane.farokhi@gmail.com 100319475328460058855 100319475328460058855 No Department of Bioscience and Technology, Faculty of Basic Sciences, Islamic Azad University, Sari ranch, Sari, Iran R. Bishekolaei Roya.Bishehkolaei@iau.ac.ir 100319475328460058856 100319475328460058856 No Department of Biology, Faculty of Basic Sciences, Islamic Azad University, Ghaemshahr Branch, Ghaemshahr, Iran