Ethanol profit margins continue to remain negative and show little sign of improving, as evidenced by DTN's hypothetical ethanol plant, which continues to suffer from low ethanol prices.Neeley Biofuels Inc., a hypothetical 50-million-gallon plant in South Dakota, saw little movement in its margin in the past month. Including debt service and depreciation, the plant continues to show a 34.4-cent-per-gallons loss, compared to a 34.5-cent-per-gallon loss last month.Most ethanol plants, however, are not paying debt service. Excluding debt and depreciation, Neeley Biofuels continues to show a 3-cent-per-gallon loss, which is unchanged from one month ago.Since our last update on Oct. 16, the corn price paid by the hypothetical plant dropped by 5 cents to $3.73 per bushel. The South Dakota rack price of ethanol received by the plant, however, remained unchanged at $1.37 per gallon.Donna Funk, a certified public accountant with K-Coe Isom based in Lenexa, Kansas, who works with ethanol plants, said the industry is struggling.