NOVELTY - Bacterium or its extract for the modification of biomass or its derivative for the preparation of product of bioenergy or metabolite sources, is new, where the bacterium is able to be developed at 40-70 degrees C and to be operated in an interval of pH (3-9.5), and is able to fully or partially reassemble its genome broken by a stress, preferably by irradiation (UV or gamma radiation), drying, enzyme, ultrasound or chemical stress.    USE - The bacterium is useful: for the modification of biomass or its derivatives for the preparation of product of bioenergy or metabolite sources; for the production of ethanol or metabolites, preferably glycerol, butanediol, propanediol, acetic acid, propionic acid, pyruvic acid and butylic acid from the biomass; to modify the sugars into 5-6 carbon; to enhance the formation of glucose from cellulose; to enhance the formation of 6-5C sugars, preferably xylose from hemicellulose; to enhance the lignin digestion; for growing bacteria other than modifying the biomass; and for growing bacteria in a reactor while modifying the biomass (all claimed).    ADVANTAGE - The bacterium economically and reliably provides production of bioenergy, preferably ethanol.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a composition used in the modification of biomass or its derivatives, comprises at least one bacterium or bacterial extract and at least one agent comprising anti-foaming agent and nutrient;    (2) a process for modifying biomass or its derivative using the bacterium or the composition, comprising culturing operation and developing bacterial strain or an extract of bacterial strain under conditions of growth and appropriate development, modifying biomass under the action of appropriate quantities of the bacterium or extract from the bacterial strain in the conditions suitable for the biomass or its derivative modification, and collecting at least a source of bioenergy or at least a metabolite obtained from the biomass modification, preferably collecting produced ethanol; and    (3) a reactor for the biomass or its derivative modification, comprising means for implementing the process or the composition.