## 2 Materials and Methods  
In this study, we used a pre-test design, followed by a post-test design. The pre-test was a test for the group of Gram-positive spore bacteria acquired from the isolation of the syringe bacteria, and the post-test was a test for _B. cereus_ bacteria. To study the isolated bacteria, a suspension was created with a microbial fuel cell (MFC) density of 0.5. The isolate was subjected to a dilution of 0.85% NaOCl with as much as 1000 mL for 24 h. The working method involved submerging sterile syringes in a suspension for eight hours to produce a biofilm on the surface of the needle with pH 7 and a brain heart infusion (BHI) nutrient substrate. This step was performed so that the process could be carried out. This methodology adhered to the protocols followed by earlier researchers [14; 15].  
Andosol soil was extracted from the highlands and utilized in the treatment. The soil was sieved with a 3 mesh sieve to obtain a particle size of 6730 microns, and it was then dried at a temperature of 1100 degrees Celsius for 12 h. At a pH of 6, sterile distilled water creates soil with a concentration of thirty per cent. This followed a recent study that found that the chemical composition of the soil, namely, the levels of Fe (levels of 11.772 ppm), Zn (levels of 0.105 ppm), and Cu, were able to lower the number of bacteria in the soil (to levels of 0.018 ppm). In addition, microorganisms could be removed from the soil using an autoclave set at 1210 degrees Fahrenheit for thirty minutes [16].  
Syringes that had been contaminated with _Bacillus cereus_ bacteria for 8 h were treated with a different combination sequence, namely, NaOCl (30 min), 30% andosol soil (2 min). This treatment was carried out three times (30 min). The exposure time was based on the duration used in previous studies when conducting experiments with andosol soil [17; 18]. In the first stage of the procedure, the syringe was submerged in a solution with a concentration that varied between 0.75 ppm, 0.375 ppm, and 0.188 ppm for thirty minutes. After that, a concentration of 0.094 ppm and 0.047 ppm of each were added to the soil suspension, and vice versa. The treatment with the NaOCl solution required a contact period of 30 min, but the andosol soil only required 2 min. The soil solution was brought to a uniform consistency by shaking it with an orbital shaker at 100 revolutions per minute. The sample from the syringe was placed in NaOCl, and the culture was carried out at 37 degrees Celsius for a full day. The final step was to compute the colony amount using the total plate count (TPC) method, which involved multiplying the number of bacteria present in a Petri dish by one and then dividing that result by the dilution factor [19]. To determine the best composition, one-way ANOVA was employed by examining the highest partial eta squared and values below 0.05 were considered significant.  
Sample replication was calculated with the Federer formula: (t - 1)(r - 1) \(\geq\) 15, which is commonly used in medical research to determine samples [20]. Since there were 13 treatments, the calculation was as follows:  
\[\begin{array}{l}(13-1)(r-1)\geq 15\\ 12(r-1)\geq 15\\ 12r\geq 15+12\\ r=27/12\\ r=2.3\sim 3\end{array}\]The number of replicates (the number of samples) was at least 3, but in this study we used a total sample number of 10. Thus, the total sample number for this study was 13 treatments multiplied by 10 = 130 samples (total samples).