## 1 Introduction  
The release of industrial wastewater has been rising steadily in recent years, causing growing levels of ammonia nitrogen pollution [1, 2]. The ecological environment, as well as human life, might be negatively impacted by the high ammonia nitrogen content of wastewater [3]. Excessive nitrogen can lead to the deterioration of air quality, eutrophication of water bodies, and the death of plants and animals in contaminated water. Physical, chemical, and biological procedures are the basic components of treatment technologies for nitrogen-containing wastewater [4]. Among them, biological methods are most often used for wastewater denitrification due to high treatment capacity, low cost, and no secondary pollution [5]. The dissolved solids in high-salinity wastewater are higher than 3.5%, while the salinity of wastewater produced by sectors such as petroleum and seafood processing is high [6, 7]. Excessive salinity inhibits the metabolism of microorganisms used in wastewater treatment systems and decreases their ability to denittify. Presently, high-salinity settings make it difficult for terrestrial denittifying microorganisms to denittify successfully [8]. It is possible to increase the effectiveness of nitrogen removal from saline wastewater and the stability of process operation by screening salt-tolerant aerobic denitrifying bacteria from marine samples [9]. Growth promoters have been used extensively in plant development [10; 11; 12] and can control cell growth and metabolism [13; 14]. They are residue-free and favorable to the environment. Moreover, promoters have the power to control an organism's metabolic pathways [15]. Gibberellin can improve salt tolerance and encourage the growth of seeds and seedlings, according to numerous studies [16; 17; 18]. [PERSON] et al. showed that indoleacetic acid has a promotion effect on the growth and synthesis of fatty acids in Chlorella dubliniensis, whereas [PERSON] et al. demonstrated that naphthalene acetic acid (NAA), an exogenous growth hormone, imparts a significant promotion effect on the growth and synthesis of lipids in Chlorella vulgaris. In a study by [PERSON] et al. [19], it was discovered that the biomass and lipid content of _C. vulgaris_ could be increased by the addition of IAA, NAA, and dichlorophenoxy acetic acid when nitrogen was scarce. Low concentrations of the compound sodiumnitrophenol (CSN) were found by [PERSON] et al. [20] to increase the rate of flower bud differentiation in oil tea by increasing ZR, IAA, and gibberellic acid 3 content in oil tea flower buds during petal formation while decreasing abscisic acid content in the late stages of flower bud morphological differentiation. For the control of wastewater treatment microorganisms, research into growth boosters is crucial. The total number of transcripts in a tissue or cell at a specific developmental stage or functional state is known as the transcriptome [21]. A novel method for analyzing transcriptomes based on deep sequencing technology is known as transcriptome sequencing [22]. Each fragment is sequenced in high throughput to retrieve the sequence at one or both ends after whole RNAs are transformed into cDNA libraries with ligation sites at one or both ends. After sequencing, reads can be compared with reference genomes and reference transcripts that already exist, or, in the absence of a reference gene sequence, an assembled gene transcript profile that includes transcript structure and levels of gene expression can be generated [23; 24]. In this study, we used transcriptomics to analyze differential gene expression and KEGG pathway analysis to investigate the metabolic mechanism of growth promoters. Differential genes were analyzed by DEGs GO enrichment to elucidate the differences in gene function levels between samples, while DEGs KEGG enrichment analysis was used to help us understand the biological functions of genes at the systemic level, such as metabolic pathways, genetic information, and cytological processes.