CHAPTER 1. GENERAL INTRODUCTION
1.2. Acetic acid bacteria
1.2.2. Taxonomy
The main phenotypic traits of AAB are: Gram-negative or Gram-variable, acidophilic, ellipsoidal to rod shape; and are mainly characterized by their capacity to incompletely oxidize alcohols, sugars and sugar-alcohols into their corresponding organic acid, such as acetic acid from ethanol or gluconic acid from glucose (Adachi et al., 2003).
After the discovery that acetification was due to the transformation of alcohol into acetic acid by the British chemist and physicist Humprey Davy (1778-1829), several theories opposed the cause of the process to be biological or strictly inorganic. Christian Persoon (1822), a Dutch scientist, first identified the main agent of acetification as a microorganism that he called Mycoderma aceti. Forty years later, Louis Pasteur (1822-1895) confirmed the effectiveness of Persoon's studies. He identified the "vinegar mother" as a large mass of living organisms needed for the transformation, and found that although air should be kept from fermenting wine, it was necessary for the production of vinegar (Mazza and Murooka, 2009).
Although the taxonomic grouping of AAB started when Kützing (1837) observed for the first time the organism in vinegar (Asai 1968; Gullo and Giudici, 2009) (Figure 4), Hansen (1879) was the first to discover that the biological agent of acetification was a mixture of bacterial species, and Beijerinck (1899) used for the first time the terminology of Acetobacter. Visser’t Hooft (1925) was the first to use morphological, physiological and biochemical characteristics of microorganisms for classification and taxonomical purposes. Using these phenotypic traits, Asai (1935) proposed the classification of AAB in two genera: Acetobacter and Gluconobacter, in the family of Acetobacteraceae. The classification proposed by Frateur (1950) was based on 5 physiological tests: catalase, gluconic acid production from glucose, acetic acid oxidation to CO2 and water, lactic acid oxidation to CO2 and water and glycerol oxidation to dihydroxyacetone; and classified Acetobacter strains in 4 groups: peroxydans, oxydans, mesoxydans and suboxydans.
Table 2. Vinegars of the world. Non-exhaustive list, modified from Gullo and Giudici, 2009).
Category Raw material Intermediate Vinegar name Geographical distribution
Vegetablea Rice Moromi Komesu, kurosu (japan)
Heicu (china) East and Southeast Asia
Bamboo sap Fermented bamboo sap Bamboo vinegarb Japan, Korea
Malt Beer Malt vinegar Northern Europe, USA
Palm sap Pal wine (toddy, tari, tuack, tuba) Palm or toddy vinegar Southeast Asia, Africa
Barley Beer Beer vinegar Germany, Austria, Netherlands
Millet Koji Black vinegar China, East Asia
Wheat Koji Black vinegar China, East Asia
Sorghum Koji Black vinegar China. East Asia
Tea and sugar Kombucha Kombucha vinegar Rusia, Asia (China, Japan,
Indonesia)
Onion Onion alcohol Onion vinegar East and Southeast Asia
Tomato --- Tomato vinegar Japan, East Asia
Fruit Apple Cider Cider vinegar USA, Canada
Pear Fermented pear juice Pear vinegar Europe, France
Pineapple Fermented pineapple juice Pineapple vinegar Africa
Grape Raisin
Fig Fermented fig juice Fig vinegar Turkey
Coconut Fermented coconut water Coconut vinegar Philippines, Sri Lanka
Date Fermented date juice Date vinegar Middle East
Mango Fermented mango juice Mango vinegar East and Southern Asia
Red date Fermented jujube juice Jujube vinegar China
Raspberry Fermented raspberry juice Raspberry vinegar East and Southern Asia Blackcurrant Fermented blackcurrant juice Blackcurrant vinegar East and Southern Asia Blackberry Fermented blackberry juice Blackberry vinegar East and Southern Asia Mulberry Fermented mulberry juice Mulberry vinegar East and Southern Asia
Plum Umeboshic fermented plum juice Ume-su Japan
Cranberry Fermented cranberry juice Cranberry vinegar East and Southern Asia Kaki Fermented persimmon juice Persimmon vinegar
Kakisu
South Korea Japan
Animal Whey Fermented whey Whey vinegar Europe
Honey Diluted honey wine, tej Honey vinegar Europe, America, Africa
aVegetable is not a botanical term and is used to refer to an edible plant part; some botanical fruits, such as tomatoes, are also generally considered to be vegetable.
bObtained by bamboo sap fermentation
cUmeboshi are pickled ume fruits. Ume is a species of fruit-bearing tree of the genus Prunus, which is often called a plum but is actually more closely related to apricot.
Figure 4. Scanning electron micrograph of AAB bacteria grown on synthetic medium. Bar = 1 µm
The 1984 edition of the “Bergey’s Manual of Systematic Bacteriology”, the reference book for bacteria taxonomy, included additional molecular tests for the classification of microorganims, as the fatty acid composition, the ubiquinone nature, the electrophoretic pattern of soluble proteins, the plasmid fingerprinting; and other genome-based tests, as the
%G+C and the DNA-DNA hybridization. Using a polyphasic approach, the genera Gluconobacter and Acetobacter were considered phylogenetically close enough to be classified in the family Acetobacteraceae (De Ley et al., 1984). At that time, the genus Acetobacter included 4 species: A. aceti, A. pasteurianus, A. liquefaciens and A. hansenii, and the genus Gluconobacter only one, G. oxydans. The main difference was the ability of Acetobacter to completely oxidize ethanol into CO2 and water, which was missing in Gluconobacter. Further research in bacterial taxonomy based on genome studies: DNA-DNA or DNA-RNA hybridization, partial and complete 16S rRNA gene analysis, MLSA/MLST using a set of up to 7 housekeeping genes, changed considerably the bacterial classification, and the Acetobacteraceae have been no exception. After those two genera, four more genera have been described and included in the Acetobacteraceae family: Acidomonas (Urakami et al., 1989), Gluconacetobacter (Yamada et al., 1997) Asaia (Yamada et al., 2000) and Kozakia (Lisdiyanti et al., 2002). Also new species have been included and the group of AAB consists nowadays of 14 genera and 68 species (Table 3), where Acetobacter and Gluconacetobacter, with 20 and 19 species, respectively, are the genera which show the highest biodiversity (Yamada, 2003). Despite the high diversity, only a few species have been described to be related with vinegar (see Table 3, highlighted species). The genus Gluconacetobacter is well separated in two groups, the so-called Ga. xylinus group, which is mostly formed by vinegar related species, and Ga. liquiefaciens group, which include nitrogen-fixing strains among their members. Some researchers have proposed to separate these two groups in two different genera, but at present there is not yet sufficient evidence to support the reclassification (Cleenwerck et al., 2010).
Table 3. Currently recognized AAB genera and species (modified from Gullo and Giudici, 2009).
Phylum Class Order Family
Proteobacteria Alphaproteobacteria Rhodospirillales Acetobacteraceae
Genus Species Sourcea Reference
ACETOBACTER
Acetobacter aceti Vinegar (Pasteur, 1864)
Beijerinck, 1898
Acetobacter cerevisiae Beer Cleenwerck et al., 2002
Acetobacter cibinongensis Fruit Lisdiyanti et al., 2002
Acetobacter estunensis Cider (Carr, 1958)
Lisdiyanti et al., 2002
Acetobacter fabarum Cocoa bean Cleenwerck et al., 2008
Acetobacter farinalisb Fermented rice flour
(khao-khab)
Tanasupawat et al., 2011
Acetobacter ghanensis Cocoa bean Cleenwerck et al., 2007
Acetobacter indonesiensis Fruit and flower Lisdiyanti et al., 2000
Acetobacter lovaniensis Soil (Frateur, 1950)
Lisdiyanti et al., 2000
Acetobacter malorum Apple Cleenwerck et al., 2002
Acetobacter nitrogenifigens Kombucha tea Dutta and Gachhui, 2006
Acetobacter oeni Wine Silva et al., 2006
Acetobacter orientalis Canna flower Lisdiyanti et al., 2002
Acetobacter orleanensis Beer (Henneberg, 1906)
Lisdiyanti et al., 2000
Acetobacter pasteurianus Beer (Hansen, 1879)
Beijerinck and Folpmers, 1916
Acetobacter peroxydans Ditch water Visser't Hooft, 1925
Acetobacter pomorum Industrial vinegar
fermentation Sokollek et al., 1998
Table 3. Currently recognized AAB genera and species (modified from Gullo and Giudici, 2009). (Cont.)
Phylum Class Order Family
Proteobacteria Alphaproteobacteria Rhodospirillales Acetobacteraceae
Genus Species Sourcea Reference
ACETOBACTER
Acetobacter senegalensis Mango fruit Ndoye et al., 2007
Acetobacter syzygii Organic apple juice Lisdiyanti et al., 2002
Acetobacter tropicalis Coconut Lisdiyanti et al., 2000
ACIDOMONAS
Acidomonas methanolica Yeast fermentation
process
(Uligh et al., 1986) Urakami et al., 1989 emend.
Yamashita et al., 2004 AMEYAMAEAb
Ameyamaea chiangmaiensisb Flower of red ginger Yukphan et al., 2009
ASAIA
Asaia bogorensis Flower or orchid tree Yamada et al., 2000
Asaia krungthepensis Heliconia flower Yukphan et al., 2004
Asaia lannaensisb Flowers of the spider lily Malimas et al., 2008
Asaia siamensis Flower of crown flower Katsura et al., 2001
Asaia spathodeaeb Flowers of the african tulip Kommanee et al., 2010
GLUCONACETOBACTER
Gluconacetobacter asukensis Stone Tazato et al., 2011
Gluconacetobacter azotocaptans Coffe plant Fuentes-Ramírez et al., 2001
Gluconacetobacter diazotrophicus Sugarcane (Guillis et al., 1989)
Yamada et al., 1997
Gluconacetobacter entanii High-acid industrial vinegar
fermentation Schüller et al., 2000
Gluconacetobacter europaeus High-acid vinegar
fermentation (Sievers et al., 1992) Yamada et al., 1997
Gluconacetobacter hansenii Vinegar (Goseelé et al., 1997)
Yamada et al., 1997 emend.
Lisdiyanti et al., 2006
Gluconacetobacter intermedius Kombucha beverage (Boesch et al., 1998)
Yamada, 2000
Gluconacetobacter johannae Coffe plant Fuentes-Ramírez et al., 2001
Gluconacetobacter kakiaceti Persimmon vinegar Lino et al., 2011
Gluconacetobacter kombuchae Kombucha tea Dutta and Gachhui, 2006
Gluconacetobacter liquefaciens Dried fruit (Asai, 1935)
Yamada et al., 1997
Gluconacetobacter nataicola Nata de coco Lisdiyanti et al., 2006
Gluconacetobacter oboediens Industrial red wine
vinegar fermentation
(Sokollet et al., 1998) Yamada, 2000
Gluconacetobacter rhaeticus Organic apple juice Dellaglio et al., 2005
Gluconacetobacter sacchari Sugarcane Franke et al., 1999
Gluconacetobacter saccharivorans Beet juice Lisdiyanti et al., 2006
Gluconacetobacter swingsii Organic apple juice Dellaglio et al., 2005
Gluconacetobacter tumulicola Stone Tazato et al., 2001
Gluconacetobacter xylinus Mountain-ash berries (Brown, 1886)
Yamada et al., 1997 GLUCONOBACTER
Gluconobacter albidus Flower of dahlia (ex Kondo and Ameyama, 1958)
Yukphan et al., 2005
Gluconobacter cerinus Cherry (ex Asai, 1935)
Yamada and Akita, 1984 emend.
Katsura et al., 2001
Gluconobacter frateurii Strawberry Mason and Claus, 1989
Gluconobacter japonicus Bayberry fruit Malimas et al., 2009
Gluconobacter kanchanaburiensisb Spoiled Jackfruit Malimas et al., 2009
Gluconobacter kondoniib Strawberry Malimas et al., 2007
Gluconobacter nephelii Fruit Kommannee et al., 2010
Gluconobacter oxydans Beer (Henneberg, 1897)
De Ley, 1961 emend.
Gosselé et al., 1983 emend.
Mason and Claus, 1989
Table 3. Currently recognized AAB genera and species (modified from Gullo and Giudici, 2009). (Cont.)
Phylum Class Order Family
Proteobacteria Alphaproteobacteria Rhodospirillales Acetobacteraceae
Genus Species Sourcea Reference
GLUCONOBACTER
Gluconobacter roseusb Persimmon fruit (ex Asai 1935)
Malimas et al., 2008
Gluconobacter sphaericusb Fresh grape (Ameyama 1975)
Malimas et al., 2008
Gluconobacter thailandicus Flower Tanasupawat et al., 2004
Gluconobacter uchimuraeb Rakam fruit Tanasupawat et al., 2011
Gluconobacter wancherniaeb Unknown eeed Yukphan et al., 2010
GRANULIBACTER
Granulibacter bethesdensis Lymph node culture from a
patient with chronic granulomatous disease
Greenberg et al., 2006
KOZAKIA
Kozakia baliensis Palm brown sugar Lisdiyanti et al., 2002
NEOASAIA
Neoasaia changmaiensis Flower of red ginger Yukphan et al., 2005
NEOKOMAGATAEAb
Neokomagataea tanensisb Flowers of candle bush Yukphan et al., 2011
Neokomagataea tahilandicab Flowers of lantana Yukphan et al., 2011
SACCHARIBACTER
Saccharibacter floricola Flower Jojima et al., 2004
SWAMINATHANIA
Swaminathania salitolerans Mangrove-associated wild
rice Loganathan and Nair, 2004
TANTICHAROENIAb
Tanticharoenia sakaeratensisb Soil Yukphan et al., 2008
Phylum Class Order Family
Proteobacteria Gammaproteobacteria Xanthomonadales Xanthomonadaceae
Genus Species Sourcea Reference
FRATEURIA
Frateuria aurantia Flower and fruit (ex Kondo and Ameyama, 1958)
Swings et al., 1980 Highlighted species (orange color) have been described to be related with vinegar production.
aRefers to the type strain isolation source.
bGenera and species waiting for validation by the Int. J. Syst. Bacteriol.