Unicube

Soil samples were collected from the central square of each plot (dimensions 2 × 2.5 m²). In each plot, 5 soil cores weighing about 400 g were collected from the root zone of 5 plants at a depth of 0–20 cm. Samples were prepared according to Miller et al. [58 ] and analyzed to determine the total N, NO₃-N, NH₄-N, and plant-available P and K concentrations. Total N in soil samples was determined by high temperature combustion using an elemental analyzer (Unicube, Elementar Analysensysteme GmbH, Hanau, Germany). To determine the concentration of mineral N (N-min, i.e., NO₃-N + NH₄-N) in the soil, each sample of sieved soil was extracted using a KCl solution, as described by Keeney and Nelson [59 ]. Subsequently, the NO₃ and NH₄ concentrations in the sample extracts were determined by applying the cadmium reduction to NO₂ and the indophenol blue methods, respectively [59 ], using a Spectronic Helios spectrophotometer (Thermo Electron Corporation, Mercers Row, Cambridge CB5 8HY, UK). Plant-available P was determined using the Olsen method [60 ] and quantified by molybdate colorimetry [61 (link)]. Exchangeable soil K was determined using a flame photometer (Sherwood Model 420, Sherwood Scientific, Cambridge, UK) following extraction with an ammonium acetate solution.

De Man, Rogosa, and Sharpe (MRS) media was purchased from BD Biosciences (Franklin Lakes, NJ, USA). A. vera powder was obtained from Morinaga Milk Industry Co. (Tokyo, Japan). ⍺-amylase, pepsin, and bile salt were purchased from Fujifilm Wako Pure Chemical Corporation (Osaka, Japan), and pancreatin was obtained from Sigma (St. Louis, MO, USA). A commercial soft drink and milk (pasteurised) were purchased from a local market. All chemical reagents used in this study were of analytical grade.
Data were collected using a muffle furnace (MFP-300A; IKEDA Scientific Co., Tokyo, Japan), an organic elemental analyser (UNICUBE; Elementar Analysensysteme GmbH Langenselbold, Germany), a scanning electron microscope (JSM-6330F; Tokyo, Japan ), a FT-IR spectrometer (FT-IR 300; JASCO, Tokyo, Japan), a zeta potential instrument (Melles Griot, Carlsbad, CA, USA), an Isoton II diluent instrument with particle size data analyser (Muiltisizer 4, Beckman Coulter, Brea, CA, USA), a high-performance liquid chromatograph (LC-10AS, Shimadzu, Kyoto, Japan), a gas chromatograph (GC-4000, TC-1; GL Sciences, Tokyo, Japan), and a colour measuring instrument (Konica Minolta, Tokyo, Japan).
Samples were prepared using a lyophiliser (Eyela, Tokyo, Japan) and spray drier (pilot-scale SD 1000; Eyela) for further analysis. Double distilled water was used in all experiments.

Starting materials and reagents were purchased from Sigma-Aldrich (Thermo Fisher Scientific, Waltham, MA, USA). The following instruments were used: IR spectra, Perkin-Elmer Spectrum One FT-IR spectrophotometer with ATR sampling unit; nuclear magnetic resonance spectra, BRUKER Avance 300 spectrometer; chemical shifts are given in parts per million (δ) downfield from tetramethylsilane as internal standard; mass spectra, Varian MAT 311A (EI); Thermo Fischer Scientific Q Exactive (ESI-HRMS); Elementar Unicube (EA).