## 1 Introduction  
Baijiu, one of China's earliest solid-state fermented distilled spirits, boasts a history spanning 5000 years [1]. Traditionally, it was yielded through grain fermentation and distillation, with esters and alcohols serving as its primary volatile compounds [2]. Recent research has identified chi-flavor baijiu (CFB) as a distinct aromatic category of baijiu [3]. CFB contains a complex microbial community, with microorganisms responsible for producing most flavor compounds. The composition of these compounds is largely determined by the diversity and dynamics of microbial communities [4]. Consequently, recent studies have focused on understanding the characteristics of microbial communities during the fermentation and their impact on flavor compound composition, as well as attempting to improve the flavor and quality of Baijiu. Numerous studies have demonstrated that the addition of exogenous and targeted microbial strains can enhance the production of flavor metabolites [5; 6; 7; 8]. [PERSON] and [PERSON] et al. found that _P. anomala_ was able to produce a wide range of flavor substances (alcohols, acids, esters, ketones, hydrocarbons, etc.) and was able to withstand extreme environmental complexity. If fermented under anoxic conditions, _P. anomala_ can also activate key enzymes in the fermentation process [9], thus increasing the contents of flavor substances (ethanol, ethyl acetate, etc.) to varying degrees. This increase in flavor contents can be achieved if _P. anomalous_ is mixed with _Saccharomyces cerevisiae_ in the fermentation process [10]. _L. plantarum_ is highly acid-resistant. It can survive in different environments. Secondly, it can directly provide nutrients for the growth and metabolism of other microorganisms [11]. Furthermore, _L. plantarum_ is able to regulate the acidic environment during the fermentation process, which is conducive to glycation and fermentation. In the late stage of fermentation, the metabolism of _L. plantarum_ produces a large amount of lactic acid, which effectively inhibits the growth of some bacteria [12]. Organic acids, such as lactic acid, acetic acid, octanoic acid, and succinic acid, can form various types of esters through esterification, producing compounds like ethyl acetate, ethyl lactate, and ethyl caprylate. These esters not only contribute to the unique flavor of baijiu but also serve as a key source of aromatic substances. Ethyl acetate content serves as a standard measure of flavor quality in light-flavor baijiu, with _Pichia pastoris_ as a crucial player in its production [13; 14]. When compared to the use of individual strains, the incorporation of mixed exogenous strains has been shown to enhance the flavor of CFB in depth. As an illustration, mixed-strain fermentation using _Pichia kudriavzevii_ and _Saccharomyces cerevisiae_ improved lactic acid tolerance within the mixed culture [15]. Moreover, the co-inoculation of _Saccharomyces cerevisiae_ and _Wickerhamomyces anomalies_ at specific ratios significantly increased the ethyl acetate content in sauce-flavor baijiu [16]. Several studies have recognized phenylethyl alcohol and (E)-2-octanal as key factors in the overall flavor of CFB, recognizing them as characteristic aromas of CFB [17; 18]. To further improve the aroma of CFB, it is crucial to investigate the intricate pertinence between the fermentation process, volatile flavor compounds, and microorganisms. However, previous research on CFB has primarily concentrated on volatile components and unique aromatic compounds [18; 19], with limited studies focusing on improving CFB's flavor through the addition of exogenous strains. High-throughput sequencing technologies have been extensively utilized to analyze microbial communities in diverse categories of baijiu [18]. Additionally, Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry (HS-SPME-GC/MS) is a common way of identifying volatile flavor compounds [3; 17; 20]. In this study, the mixed strains _P. anomalous_ and _L.