## 1 Introduction  
Winemakers have long been seeking river fruits for the aim of producing fuller-bodied wines that are preferred by both the consumers and wine experts [1]. This trend has been exacerbated over the past two decades [2]. However, due to climate warming and extreme weather events, excessive sugar accumulation and loss of organic acids in grape berries upon ripening is frequently seen in warm regions and has become one of the major concerns for winemakers [3]. Such grapes not only exert difficulties for successful and timely completion of alcoholic fermentation, but also would easily induce inferior sensory properties often linked with unbalanced low acidity. Inadequate acidity may also increase the likelihood of microbial spoilage, which would be detrimental for both the chemical and sensory profile of the wine [4]. Thus, there is a strong demand to develop appropriate strategies to managing wine acidity. Currently, insufficient wine acidity in warmer regions is commonly corrected via supplement of authorised organic acids such as tartaric, lactic and malic acids [5]. Alternatively, winemakers can opt for physical acidification of wines based on ion exchange [6], electrodialysis [5], and blending with wines made from earlier harvested grapes [7]. Albeit efficient, these approaches can be limited by extra costs resulting from additional requirements of labours and equipment, or by consumer perception. For example, wines made from grapes at an early ripening stage contributed to fresh green and red fruit characters rather than the jammy fruit aroma and palate that are favoured by many consumers [8]. In comparison, the application of acidifying wine microbes could offer an inexpensive and straightforward solution, with potential to modulate wine flavour. Generally, acidifying wine microbes are capable of synthesizing considerable amounts of lactic acid that are more microbially and chemically stable with rounder flavour and mouthfeel. In recent years, growing interest has focused on using _Lachancea thermotolerans_, a non-conventional yeast, to enhance the overall quality of wines that suffer from insufficient acidity [9; 10]. The yield of lactic acid by _L. thermotolerans_ yeasts would lead to the decrease in wine pH by 0.01--0.5 units [9]. Varied pH changes often linked with differential lactic acid production capability by the yeast, which can be influenced by many factors, encompassing strains [9; 10], inoculation regimes [9], and fermentation conditions (e.g., fermentation temperature and SO\({}_{2}\) addition [10]). The most productive _L. thermotolerans_ strain formed 16.6 g/L lactic acid under oenological conditions during fermentation [11]. Aside from _L. thermotolerans_, wine lactic acid bacterium _Lactiplantiobacillus plantarum_ (formerly known as _Lactobacillus plantarum_[12]) also has such potential [13; 14]. Normally, _L. plantarum_ (henceforth LP) can present on grape skins and at different stages during winemaking [15]. They are rod-shaped bacteria and are best known as an ideal alternative to _Oenococcus oeni_ for efficient malolactic fermentation (MLF) in wines with high pH [16]. Apart from MLF, LP displays a homofermatative character for hexose, which allows this specific bacterium to generate lactic acid as the sole metabolite through hexose catabolism, known as lactic fermentation [13; 17; 18]. This special feature makes LP a promising candidate as an acidifying starter culture without the risk of producing acetic acid, which is the major component of wine volatile acidity. [PERSON] and [PERSON] reported the inoculation of commercial LP 10 days prior to addition of _Saccharomyces cerevisiae_ (henceforth SC) led to the production of up to 8.3 g/L acid in Carmenere wine, and a reduction of 0.4 units in pH [14]. In this scenario, lower acetic acid yield (0.40 g/L) was observed, whilst 0.65 g/L acetic acid was detected in wines produced with co-fermentations of _O. oeni_ and SC [14].