COMMENTS FROM REFEREES: (Comments in attachment form should be accessed from your corresponding author centre) Reviewer 1 Comments: 1. General Comments The Introduction clearly describes the background and significance of the work. The Materials and Methods section is short on the details of the work. The Discussion does not adequately describe the work in relation to other research. The manuscript is very readable. 2. Specific comments a. Major 1) The experimental conditions described on lines 74-81 are incomplete. The concentration and source of tobacco waste used in the experimental runs, results of which are shown in Table 2, are not reported. Also, the length of the experimental runs should be reported in this section. The only reference to the run time is given on line 170. It is not sufficient to report only the percent nicotine degradation, but the overall rate and amount of nicotine degraded should be determinable. Also, the amount and source of materials should be reported. Ø The experiment conditions were supplemented in revised manuscript. Please see on line 80-91. Ø The tobacco waste was collected from Bengbu Cigarette Co. Ltd., Anhui of P.R. China and the content of nicotine is about 1.36 %. Please see on line 82-84. Ø The content of nicotine was about 1.36 % in tobacco waste and 1220 mg/L in tobacco extract. Ø The specific biodegradation rates of nicotine were compared with the other nicotine-degrading bactria in application. Please see on line 207-212 and table 4 on line 330. Ø The time of experimental runs was 12 h in CCD experiment. Please see on line 87. Ø In optimal conditions, the percent nicotine degradation, overall rate and amount of nicotine degraded were determined. Please see on line 181-183. The tobacco waste used in the optimal experiment also was collected from Bengbu Cigarette Co. Ltd, Anhui of P.R. China. Please see on line 82-84. 2) The authors should discuss the use of optimum amounts and whether these optimum amounts could be used on a large scale. For example, would the cost of Tween 80 and yeast extract be reasonable at approximately 1 g/L? Ø The economics of biodegradation needs to be analyzed and the costs compared with those of other nicotine degradation methods. In this study, source supplement could improved nicotine degradation and reduced time of nicotine degradation. The results indicated that strain DN2 could be used on a large scale. On the other, source supplement will increase the operating costs. However, yeast extract, glucose and Tween 80 were commercially available and inexpensive. Please see on line 213-220. 3) Comparisons should be made with previous work. In particular, rates of nicotine degradation should be compared with previous work. A key reference for this is the Uchida et al. paper. The journal cited is Science Paper. Is this the correct citation? I could not locate this paper. Ø In revised manuscript, we compared our results with previous work. Please see online 208-213 in discussion section. Ø Uchida et al. paper is Japanese. I don’t understand Japanese, so I did not understand accurately mean of the paper. I asked a teacher from Japan, conclusion of the paper