NOVELTY - Method (M1) for producing a fatty ester composition involves: providing at least two different alcohols in a single mixture, where the alcohols contain different numbers of carbon atoms; and adding the single mixture to a medium containing a fatty ester production host, so that the fatty ester production host produces at least two different fatty esters.    USE - For producing fatty ester composition, where the fatty esters are selected from fatty methyl ester, fatty ethyl ester, fatty isopropyl ester, and/or fatty propyl ester; or fatty butyl ester, fatty pentyl ester, fatty hexyl ester, fatty heptyl ester, fatty octyl ester, fatty nonyl ester, and/or fatty decyl ester; which are useful for producing a biofuel (claimed).    ADVANTAGE - The method allows for production of desired or customized fatty ester mixtures, which are useful for producing customized biofuels, by using greater than or equal to 2 different alcohols in combination with fatty ester production host. Thus, the method allows for customization of biofuel's properties based upon the alcohols used with the production host; as compared to the prior art method in which the biological production host is utilized to produce specific fatty ester, which can then be incorporated or modified into biofuel, to obtain desired fuel properties such as cloud point, cetane number, viscosity, and lubricity that changes considerably depending on alcohol moiety incorporated into fatty ester; in which when properties of a single specific fatty ester are ideal for its use, relatively little additional manipulation is required to use fatty ester as or in fuel; but in situations where the inherent properties of specific fatty ester are not ideal, subsequent manipulation of composition is required so that a final product with the desired properties is achieved. The method provides an improved method for production of fatty ester composition, in which the properties of fatty ester composition can be manipulated through the use of a combination of different fatty esters (e.g. fatty esters having different degrees of unsaturation or chain lengths) so that resulting fatty ester mixture has desired properties. This is achieved by producing various fatty ester compositions, via production hosts and selection of different alcohols, and then combining fatty ester products to achieve desired fatty ester composition. The production of fatty esters in production hosts provides opportunity to tailor final fatty ester mixture through various, earlier, biological manipulations. The customization process for producing a desired fatty ester mixture can begin before any fatty ester is present. By selecting various types and/or amounts of alcohols to combine with a fatty ester production host, it is possible to make a variety of fatty esters concurrently. This in turn allows obtaining desired final combination of fatty esters, with desirable properties as a mixture (e.g. high cetane number and low melting point), and eliminates or reduces need for subsequent manipulation of fatty ester product in its adaptation to fuel. The fatty esters of the fatty eater compositions (C1) and (C2) have a fraction of modern carbon of 1.003-1.5; and delta 13C of -10.9 to -15.4. The use of methanol results in total amount of fatty ester produced that is greater than amount of fatty ester that is produced when the methanol is replaced with different alcohol. The amount of free fatty acids that results from the method is less than an amount of free fatty acid produced when at least one different alcohol is used without methanol. The presence of methanol results in fatty ester composition that is biased to include more fatty esters with 16, 17 and/or 18C chain, in comparison to method where only alcohol is ethanol. The presence of ethanol results in fatty ester composition that is biased to include more fatty esters with 12, 13 and/or 14C chain, in comparison to method where only alcohol is methanol. Further, method allows for reduction in number of production, concentration, or purification steps; allows for reduction in space and/or increase in speed; and allows for single vessel to serve for fatty ester production process. The host system further forms primarily or only saturated and monounsaturated fatty esters; in contrast, plant oils are rich in di- and tri- unsaturated fatty acids, are less stable to oxygen, and result in significant handling and storage constraints. The fuels produced contain less transesterification catalyst, compared to petroleum derived fuels or biodiesel derived from triglycerides.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a fatty ester composition (C1) comprising: a production host comprising a nucleic acid sequence encoding for at least one of thioesterase enzyme, acyl-coenzyme A (CoA) synthetase, enzyme and ester synthase enzyme: a first fatty ester of formula B1aCOOA'1, and a second fatty ester of formula B2aCOOA'2;    (2) a fatty ester composition (C2) comprising: a first fatty ester of formula B'1COOA'1, a second fatty ester of formula B'2COOA'2, where A'1 is different from A'2;    (3) a biofuel comprising: the fatty ester composition (C1) or (C2), or the fatty ester produced by the method (M1); and    (4) a production system comprising: a fatty ester production vessel; a first fatty ester of formula B'1COOA'1, a second fatty ester of formula B'2COOA'2, and a third fatty ester of formula B'3COOA'3.    B1a and B2a=6-30C chain;    B'1, B'2 and B'3= greater than or equal to 6C chain;    A'1, A'2 and A'3=1-5C alkyl.