Metabolomics and Nutritional Profiling of Azolla microphylla: Insights from Amino Acid Quantification and GC-MS Analysis
Abstract
Azolla microphylla, a free-floating nitrogen-fixing aquatic fern, has emerged as a promising sustainable bioresource owing to its rapid biomass accumulation, high protein content, and rich phytochemical composition. The present study investigated the seasonal growth dynamics, biomass productivity, nutritional composition, amino acid profile, mineral content, and phytochemical constituents of A. microphylla cultivated under controlled pond conditions across three climatic quarters over one annual cycle. Species authentication through molecular barcoding confirmed 99% homology with Azolla microphylla. Biomass productivity exhibited significant seasonal variation (p<0.05), with maximum wet biomass yield (40,584.25±2,093.37 kg ha⁻¹) and dry matter yield (8,116.85±418.60 kg ha⁻¹) recorded during Q1 (May-August), characterized by elevated temperature, humidity, and rainfall, whereas reduced yields were observed during Q2 (September-December) under comparatively cooler and drier environmental conditions. Despite fluctuations in biomass production, proximate analysis demonstrated substantial nutritional stability throughout the year, with crude protein content consistently maintained at approximately 30%, indicating resilience of nitrogen assimilation and protein biosynthesis under varying climatic conditions. Amino acid profiling revealed significant seasonal modulation (p<0.05), with elevated concentrations of leucine, lysine, glutamic acid, glycine, threonine, and isoleucine during Q2, while arginine and methionine reached maximum levels during Q1. Mineral analysis confirmed the presence of appreciable concentrations of calcium, phosphorus, potassium, magnesium, sodium, and zinc, supporting the nutritional suitability of the biomass for feed applications. GC–MS analysis of the n-hexane extract identified twelve major phytochemical constituents, predominantly fatty acids, phytosterols, and long-chain hydrocarbons, including stigmasterol (42.30%), phytol (23.79%), n-hexadecanoic acid (12.35%), oleic acid, campesterol, and gamma-sitosterol, compounds previously associated with antimicrobial, antioxidant, antiinflammatory, and pharmacological activities. Collectively, the findings indicate that optimum cultivation of A. microphylla is achieved at temperatures ranging from 29 to 33ºC and pH 6.3-6.8, while its stable nutritional quality and diverse bioactive profile establish this species as a sustainable alternative feed resource and a potential reservoir of industrially and pharmacologically valuable metabolites.