## 4 Discussion

Table 3: Flavor compounds (ug/L) produced from natural community and combinations of strains as synthetic communities in a biofilm cultivation device with artificial rice media. The major flavor compounds found in this study were ester group that provide a pleasant flavor to wine. The type of ester formed depended on the fermentation environment including temperature and level of alcohol [35]. [PERSON] and his team revealed that high concentrations of amino acids in grape must was also shown to enhance the production of more volatile esters [36]. Similarly, red rice is considered as rice containing highest protein as well as free amino acid by comparison with white sticky and non-sticky rice [37]. Beside this, microbial interaction also has a tremendous impact on flavor compound secretion. Based on Table 2, the type and concentration of ester group, as well as other groups, were affected by the combination of species. Metabolite production can indeed be considerably modified by the microbial composition [14; 38]. Based on the results accumulated during this work, we have shown that a simple co-culture _Ro-Sc-lp_ 1:1:1 could provide high ethanol yield and alike flavor profile by comparing to the natural community; moreover, it could reduce some undesired flavors and lower acid which could have off-flavor and taste, especially acetic acid. This might probably because of various and unknown microorganism involved in traditional brewing process and led to difficult control and microbial competitive interaction [13]. The different combination of these three strains has somehow different impacts on chemical compositions of rice wine including lactic acid, acetic acid, and ethanol yield. These three strains together were able to produce flavor profile which was similar to that from natural microbial community, regularly used in rice wine production in Cambodia. Beside the optimization of the cultivation medium and consortia members, alternative cultivation device can also be proposed. The selection of microbes for specific aroma profile cannot be effective without understanding how microbe interact with each other [14]. In such a case, a biofilm cultivation has been used for promoting the spatial structuration of the three microbial strains extracted from the original starter [17; 23]. Indeed, the metallic support used in this device have been previously reported as enhancer the natural binding of filamentous fungi _Trichoderma reseei_[20] and _Aspergillus oryzae_[17]. The design of cultivation media promoting metabolic interaction and the design of alternative cultivation device enhancing natural spatial organization of community are both necessary for the study of microbial community [18; 19]. Fungal spores generally prefer to adhere and develop on lateral surfaces by several mechanisms involving complex interactions between physical and biological factors. Thus, inserting solid support in the middle flask is very important for the growth of filamentous fungi. Filamentous fungi in submerged and semi-solid conditions always cause problem of increasing viscosity and forming different morphologies leading difficulties of system control during production, notably; cereal-based fermentation [16]. Rice wine production techniques were commonly performed in simultaneous saccharification and fermentation (SSF) method by which starch enzymatic hydrolysis and alcoholic  
Figure 4: Scheme showing microbial interaction in biofilm cultivation device. (**A**) hypothetical metabolic interactions between fungi, yeast, and LAB, and the resulting functions during red rice wine fermentation (or on the synthetic liquid medium). (**B**) Scheme showing the biofilm cultivation device used in this study, i.e., a shake flask with a stainless steel packing sheet, as well as the expected positions of fungi, yeast, and LAB species during fermentation. ferentation occur simultaneously in the same reactor. Using SSF can eliminate the inhibition of saccharifying enzyme by sugar substrate [39] and give unique flavor of rice wine [4; 40].