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<br /> �Y _115 between the principal species of fluorescent pseudomonads
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<br /> MOLES RIo NUMBER Or GROWTHi
<br /> G + C - HYDROLYSIS
<br /> FLAGELLA PER FRODUCr10N AT , !
<br /> IN DNA CELL OF PYOCYANIN OF OXIDASE DENTRIFI-
<br /> QS'c GELATIN REACTIONi.t;ri.,
<br /> CATION
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<br /> 58-60 >1 _ — + + - VR }.44111
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<br /> w461e within species.
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<br /> OH as a cellular reserve material. In addition to the yellow fluorescent pigments,
<br /> =x ,
<br /> pyotyanin,a blue phenazine pigment(Figure 19.3), is characteristic of the species
<br /> P. aeruginosa. This species, P. /luorescens, and P putida are common members of "'
<br /> the microflora of soil and water, and are all nutritionally highly versatile, being
<br /> able to use 60 to 80 different organic compounds as sole sources of carbon and
<br /> CH, energy. For this reason, they have been much studied by microbial biochemists
<br /> as biological material for the elucidation of the special metabolic pathways in-
<br /> 19•a volved in the dissimilation of different classes of organic compounds. They have 1
<br /> of pyD- also recently become accessible to genetic study, following the discovery of
<br /> bili gment conjugational and transduction! systems of genetic transfer within the group. ;;•-,'-�,
<br /> ar ugi„FIR, One outcome of this work has been the discovery that the genetic.determinants V
<br /> rr governing 4
<br /> A g g certain of the special pathways of substrate dissimilation (eg., the k
<br /> pathway for camphor dissimilation) are carried on plasmids, transmissibie from
<br /> strain to strain (see Chapter 15). r�'-
<br /> P. aeruginosa, which has a considerably higher temperature maximum than P.
<br /> lluorescens and P.putida,is sometimes pathogenic for man.It belongs to the category
<br /> of opportunistic pathogens,which do not normally exist in animal hosts,but which "«
<br /> can establish infections in individuals whose natural resistance has been reduced. t
<br /> Thus, P. aeruginosa typically causes infections, not infrequently fatal, in victims i
<br /> of severe burns and in cancer patients who have been treated with immuno- ! s.
<br /> suppressive drugs.
<br /> The fluorescent pseudomonads also include organisms that are pathogenic for G;
<br /> plants;the many varieties,which differ in host range,are assigned to one species,
<br /> P syringae. These plant pathogens are true parasites,readily distinguishable from t
<br /> the free-living soil and water species by their physiological and biochemical r
<br /> properties. They are less versatile nutritionally; and their growth rates, both in
<br /> synthetic and in complex media, are much lower. They are also the only oxidase
<br /> negative members of the fluorescent group.
<br /> The pseudomallei group (Table 19.6), like the fluorescent group, are nutri-
<br /> tionally versatile organisms which do not require growth factors.Although usually
<br /> pigmented,they never produce a yellow-green diffusible fluorescent pigment,and
<br /> they all synthesize poly-,6-hydroxybutyrate as a reserve material. The prototype
<br /> of this group,P.pseudomallei,was originally discovered as the agent of melioidosis,
<br /> a highly fatal tropical disease of man and other mammals. Even in the tropical
<br /> areas where melioidosis is endemic, it is a relatively rare disease, typically con-
<br /> tracted through the contamination of wounds with soil or mud. In fact, P. pseudo-
<br /> mallel appears to be,like P.aeruginosa, an opportunistic pathogen which is a normal
<br /> 595
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