## 4 Discussion
Therefore, the analyzed biomass, characterized by high C and low S levels, represents a viable candidate for sustainable biofuel production. This biomass can effectively be converted into high-energy biofuel with reduced environmental impacts, especially in terms of NOx emissions during combustion [63]. The analysis of the fatty acid profiles of the microalgal biomass cultivated under diverse conditions demonstrated significant variability, reflecting the adaptability of the microalgae to different environmental and nutritional contexts. Table 2 reveals that palmitic acid (C16:0) was consistently found across all the conditions, with concentrations ranging from 17.0% to 24.4%, indicating its importance in maintaining the structural integrity of cell membranes and suggesting robust membrane stability, which is essential for algae to thrive in different environments [65; 66]. The concentration of oleic acid (C18:1), the only detected MUFA, varied between 10.5% and 18.5%. Its presence is beneficial for biodiesel production, reducing fuel viscosity and improving its cold flow properties, with its variability likely due to the different environmental stresses impacting algal metabolism [67; 68]. PUFAs, especially \(\alpha\)-linolenic acid (C18:3), were prominent, ranging from 36.6% to 44.9%. These PUFAs are crucial for cellular membrane fluidity and overall physiological processes, although their high concentrations pose challenges for biodiesel stability due to their oxidation susceptibility [69]. The diverse fatty acid profiles underscore the impact of cultivation conditions on lipid metabolism, suggesting that targeted adjustments can optimize biomass for specific uses, such as biofuel production or dietary supplementation. For instance, enhancing the MUFA content can improve biofuel properties, while boosting PUFAs can increase the nutritional value of supplements [70; 71]. This strategic modulation of fatty acid profiles enhances our understanding of algal lipid biology and underscores the potential for commercial exploitation of microalgal biomass in various industries through aligning the growth conditions with the desired lipid outcomes to meet specific industry standards. The IV serves as a critical indicator of unsaturation levels in biodiesel, significantly influencing its stability and performance [72; 73]. The measurements in Table 3 show that the IV ranged from 134 to 173, reflecting a substantial presence of UFAs. This high unsaturation level enhances biodiesel's cold flow properties, as unsaturated fats have lower melting points that improve performance in colder climates [74; 75]. However, the high levels of PUFAs and their corresponding high IV values result in a low CN, which does not meet the standard requirements. Despite this, the high unsaturation level offers considerable advantages for biolubricant applications where reduced viscosity and high fluidity are beneficial [76; 77]. Biolubricants that leverage the high unsaturation level can undergo chemical modifications to enhance properties such as lubricity and viscosity, making them suitable for a range of specialized applications. Oils can be classified based on their IV into drying (IV > 130), semi-drying (100 < IV < 130), or non-drying (IV < 100) oils, with higher unsaturation levels facilitating greater chemical adaptability for biolubricant applications [78]. This adaptability is not only useful in traditional fuel applications but also extends to high-performance lubricants, where specific performance characteristics are required. Modifying fatty acid profiles linked to high IV values enhances biodiesel's lubricity and viscosity index, broadening its applications into markets requiring specialized lubricant performance.