Chloramphenicol

The fermentation process was monitored twice per day by measuring the weight loss of the bottles due to the CO₂ release. The fermentations were stopped when the weight loss was less than 0.1 g in 12 h. After alcoholic fermentation, grape pomace was separated from wine carefully, centrifuged, and stored at –20^°C for further analysis.
The viable cell count was performed by identifying colony colors using 100 mg/L of chloramphenicol (Solarbio, Beijing, China) that was added to Wallerstein Laboratory (WLN) nutrient agar (Qingdao Hope Bio-Technology Co., Ltd., China). One hundred microliter aliquots were plated onto WLN plates. After 48 h of incubation at 30^°C, the cells could be differentially counted based on the morphological particularities presented by the non-Saccharomyces yeasts that distinguished them from S. cerevisiae.

Each sample consisted of five slices (20 ± 4 g) was blended with 225 ml of sterile physiological saline (8.5 g L⁻¹ NaCl) using a sterile stomacher bender (Qingdao Hope Bio‐Technology Co., Ltd, Qingdao, China) for 2 min at high speed. A 100 μl sample of each filtrate and its appropriate dilution was spread on agar plates. The aerobic plate count (APC) was determined by plating samples on plate count agar (Aoboxing Bio‐Technology Co., Ltd, Beijing, China) and incubated at 37°C for 24 hr. Mold and yeast (M&Y) enumeration was performed by plating on potato dextrose agar (Aoboxing Bio‐Technology Co., Ltd, Beijing, China) supplemented with 200 mg L⁻¹ chloramphenicol (Solarbio Science & Technology Co., Ltd, Beijing, China) and incubated at 28°C for 48 hr. Microbial colonies were reported as log CFU g⁻¹ of tissue.

First, E. coli K12 (MG1655) was been sequenced (Shanghai Majorbio Bio-pharm Technology Co., Ltd), which was designated as the original wild type strain (Table 1). Activating E. coli from storage tube with glycerol stock which stored in − 80 °C, expanding propagating on a Luria Bertani (LB) agar plates, cultured at 37 °C for 16 h. The selected seed strain was cultured in LB broth at 37 °C for 12 h for following selected experiments (Li et al. 2016 (link)).Table 1

The MIC of each antibiotic to wild-type E. coli K12

No	Antibiotics	Abbreviation	Classification	Stock solution (mg/L)	MIC (mg/L)
1	ciprofloxacin	Cip	Quinolones	200	0.2
2	tetracycline	Tet	tetracyclines	10	2.34
3	Gentamicin	Gen	Aminoglycosides	10	8.75
4	polymyxin B	Pol	Polypeptides	10	0.94
5	erythromycin	Ery	Macrolides	6.4	15
6	chloramphenicol	Chl	chloramphenicols	30	4.69

The involved antibiotics: chloramphenicol (Chl), ciprofloxacin (Cip), erythromycin (Ery), gentamycin (Gen), tetracycline (Tet), and polymyxin B (Pol) and cupric (CuSO4·5H2O) were get from Solarbio, Inc. (Shanghai, China). 90% inhibition of growth was regarded as the MIC of each antibiotic, which was determined as Additional file 1: Test S1 described, and the MIC of copper ions was also investigated with the same method. The detailed accounts are displayed in Additional file 1: Text S1. The tetracycline resistant cultures were kept from light so as not to degrade the antibiotic.