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. 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? 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. 4) On line 91 it is stated that runs were made in duplicate. The data presented in Table 2 and the analysis from Table 3 do not show duplicate runs. b. Minor 1) The pure error term listed in Table 3 appears to be the total corrected error, corrected for the mean, and not the pure error. Reviewer 2 Comments: 1 General comments: The paper deals with an important applied aspect of nicotine biodegradation by bacterium. Additionally, the use of factorial analysis to predict the best composition of medium to give the best nicotine degradation rate it is very relevant to this field. In conclusion, the paper is a good piece of work. 2) Specific comments for revision: The paper needs an editing revision in order to improve the final version. Many words are stick; 祃 must be replaced by 礚; in my version 篊 appears as an open square; in pag. 7, l.136, Liu et al. 2003 is missing in the reference list. 我们的答复： Response to Editor and Response to Reviewers Dear editor, I delayed the revised manuscript because my son was born last month. Moreover, I supplemented one validation experiment using 30 l Bioreactor. Hence, the results of validation experiment in the original manuscript replaced by new results in the revised manuscript thus may be much useful. Besides, I revised the paper according to editor and reviewer comments. I addressed the issues raised about the description of some my methods and compared our results with other studies. Quality of table and figures also was improved. Best wishes to you! Yours sincerely, Doctor *