Fungi are ecologically ubiquitous organisms on earth and regarded as one of the prolific sources of natural products. Fungal endophytes may provide essential prerequisite molecules to plant biochemical pathways which allow the efficient synthesis of primary and secondary metabolites. This study characterized the influences of various combinations of process parameters namely, carbohydrate, nitrogen, and phosphorus sources on citric acid (CA) production by the isolated fungal endophyte Aspergillus fumigatus P3I6 from Citrus microcarpa. Aspergillus fumigatus P3I6 had higher CA concentration of 9.2 (± 0.9) g L⁻¹ and 9.0 (± 5.0 × 10⁻¹⁵) g L⁻¹ when supplemented with sucrose and white refined sugar, respectively, than A. niger NRRL 599. Response Surface Methodology (RSM) had shown that A. fumigatus P3I6 produced the highest CA (23.8 g L⁻¹) in Combination 4 (18.0% sucrose, 0.3 g L⁻¹ ammonium sulfate, and 5.0 g L⁻¹ dipotassium phosphate (K₂HPO₄)). Analysis of variance showed that when K₂HPO₄ concentrations were increased, CA content in fermentation media was significantly elevated. Hence, K₂HPO₄ was the most critical variable in the quadratic model (p < 0.05); however, sucrose concentration still has its role in production. Aside from using A. niger in most fermentation processes, this discovered fungal strain can be potentially used in biotechnological applications.

真菌是地球上无处不在的生物，被认为是天然产物的多产来源之一。真菌内生菌可以为植物生化途径提供必要的先决条件分子，从而可以有效合成一级和二级代谢产物。这项研究的特点是过程参数的各种组合，即碳水化合物，氮和磷源，对分离自柑桔皮的真菌内生真菌烟曲霉P3I6产生柠檬酸（CA）的影响。烟曲霉P3I6的CA浓度较高，为9.2（±0.9）g L ^-1和9.0（±5.0×10 ^-15）g L ^-1分别比黑曲霉NRRL 599补充蔗糖和白色精制糖。响应面方法学（RSM）显示，烟曲霉P3I6在组合4中产生最高的CA（23.8 g L ^-1）（18.0％蔗糖， 0.3g L ^-1硫酸铵和5.0 g L ^-1磷酸二钾（K ₂ HPO ₄）。方差分析表明，当K ₂ HPO ₄浓度增加时，发酵培养基中的CA含量显着增加。因此，K ₂ HPO ₄是二次模型中最关键的变量（p <0.05）; 然而，蔗糖浓度仍在生产中发挥作用。除了在大多数发酵过程中使用黑曲霉外，这种发现的真菌菌株还可以潜在地用于生物技术应用中。