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To make semicrystalline, high‐melting PLA, stereochemically pure lactic acid is needed. Not all microorganisms yield such stereochemically pure lactic acid and some even produce a racemic mixture [29]. Therefore, a strain must be chosen that meets the quality demands. Finding such a strain that produces L‐lactic acid in an economically feasible manner is relatively easy. Producing D‐lactic acid by bacterial fermentation on an industrial scale is far more difficult.

Several natural D‐lactic‐acid‐producing bacterial species exist; Sporolactobacillus inulinus, Sporolactobacillus laevolacticus (previously Bacillus laevolacticus), and Lactobacillus delbrueckii are among these bacteria [29, 42, 43]. Also, patents have been filed claiming the production of D‐lactic acid by a genetically modified microorganism. Several different species such as Kluyveromyces and Escherichia coli have been claimed so far [44, 45].