Editing Malolactic fermentation (section)

===''Lactobacillus''===
[[File:20101210 014809 LactobacillusBulgaricus.jpg|right|thumb|''Lactobacillus'' from a yogurt sample.]]
Within the genus ''Lactobacillus'' are both heterofermentative and homofermentative species. All lactobacilli involved in winemaking are Gram-positive and [[microaerophilic]], with most species lacking the enzyme [[catalase]] needed to protect themselves from [[oxidative stress]].<ref name="Wine Micro"/>

Species of ''Lactobacillus'' that have been isolated from wine and grape must samples across the globe include ''[[L. brevis]], [[L. buchneri]], [[L. casei]], [[L. curvatus]]'', [[L. delbrueckii subsp. lactis|''L. delbrueckii'' subsp. ''lactis'']], ''[[L. diolivorans]], [[L. fermentum]], [[L. fructivorans]], [[L. hilgardii]], [[L. jensenii]], [[L. kunkeei]], [[L. leichmannii]], [[L. nagelii]], [[L. paracasei]], [[Lactobacillus plantarum|L. plantarum]]'', and ''[[L. yamanashiensis]]''.<ref name="Wine Micro"/>

Most ''Lactobacillus'' species are undesirable in winemaking with the potential of producing high levels of [[volatile acidity]], off odors, [[wine haze]], gassiness, and [[sediment (wine)|sediment]] that can be deposited in the bottle, especially if the wine had not been [[filtered (wine)|filtered]]. These bacteria also have the potential to create excessive amounts of lactic acid which can further influence the flavor and sensory perception of the wine. Some species, such as the so-called "ferocious ''Lactobacillus''", have been implicated in causing sluggish or [[stuck fermentation]]s, while other species, such as ''L. fructivorans'', have been known to create a cottony [[mycelium]]-like growth on the surface of wines, nicknamed "Fresno mold" after the wine region where it was discovered.<ref name="Boulton"/>