NOVELTY - One or more isolated petroleum-based plastic-degrading bacterial cells of a bacterial strain, are new. The cells degrade one or more petroleum-based plastics in an amount of at least 100 fold greater than the dry weight of the cells when the cells are grown in the presence of the petroleum-based plastics for a period of time of 10-90 days at a temperature of 25-37 degrees C, at a pH of 6-7.5, and a dissolved oxygen content of 0.3-4 mg/l.    USE - The bacterial cells are useful for: degrading one or more petroleum-based plastics, where the petroleum-based plastics are the sole carbon source and waste petroleum-based plastics, preferably polystyrene (PS), polyethylene (PE), polypropylene (PP), PVC, polyethylene terephthalate (PET), or polycarbonate (PC); and producing a biomass product, where the biomass product is lipids, fatty acids, proteins, and/or chitin, and the biomass product is useful as feedstock in the production of at least one commodity chemical, preferably a biofuel, and as feedstock in the production of an emulsifier, a surfactant, a lubricant, a flocculant, a transformer oil, food, feed, a pharmaceutical, a fertilizer, a cleaning product, a healthcare product, and/or a cosmetics product (all claimed).    ADVANTAGE - The bacterial cells are capable of easily and efficiently degrading petroleum-based plastics at high rates within a period of less than 30 days.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) an isolated microbial consortium comprising the bacterial cells;    (2) a composition comprising the bacterial cells or the isolated microbial consortium;    (3) a method-A of degrading one or more petroleum-based plastics, comprising either culturing the composition with one or more petroleum-based plastics under conditions sufficient for the composition to degrade the petroleum-based plastics, or contacting larvae of at least one petroleum-based plastic-degrading insect with one or more petroleum-based plastics, and growing the larva with the petroleum-based plastics under conditions sufficient for the larvae to degrade the petroleum-based plastics, to yield a degraded petroleum-based plastic product; and    (4) a method-B of producing a biomass product, comprising contacting larvae of at least one petroleum-based plastic-degrading insect with one or more petroleum-based plastics, and growing the larva with the petroleum-based plastics under conditions sufficient for the larvae to metabolize the petroleum-based plastics, where the larvae utilize the metabolized one or more petroleum-based plastics to produce at least one biomass product.