26
Modern Food Microbiology
Serratia (ser • ra’ti • a). These Gram-negative rods that belong to the family Enterobacteriaceae are
aerobic and proteolytic, and they generally produce red pigments on culture media and in certain
foods, although nonpigmented strains are not uncommon. S. liquefaciens is the most prevalent of the
foodborne species; it causes spoilage of refrigerated vegetables and meat products. The mol% G + C
content of DNA is 53–59. Interestingly, a spore-forming S. marcescens isolate has been reported and
named S. marcescens subsp. sakuensis.
1
Shewanella (she • wa • nel’la). The bacterium once classified as Pseudomonas putrefaciens and later
as Alteromonas putrefaciens has been placed in this genus as S. putrefaciens. They are Gram-negative,
straight or curved rods, nonpigmented, and motile by polar flagella. They are oxidase positive and
have a mol% G + C of 44–47. The other three species in this genus are S. hanedai, S. benthica, and
S. colwelliana. All are associated with aquatic or marine habitats, and the growth of S. benthica is
enhanced by hydrostatic pressure.
14,32
Shigella (shi • gel’la). All members of this genus are presumed to be human enteropathogens; they
are discussed further in Chapter 26.
Sphingomonas (Sphin • go • monas). There are at least 33 species of this genus of Gram-negative
bacteria that typically produce yellow pigment, and which formerly were in the genus Flavobacterium.
They are found in water, on certain vegetables, and cause human disease.
58
Staphylococcus (staph • y • lo • coc’cus; grape-like coccus). These Gram-positive, catalase-positive
cocci include S. aureus, which causes several disease syndromes in humans, including foodborne
gastroenteritis. It and other members of the genus are discussed further in Chapter 23. The former
S. caseolyticus has been transferred to the new genus Macrococcus as M. caseolyticus.
29
Stenotrophomonas (Ste • no • tro • pho • mo’nas, a unit feeding on few substrates). These Gramnegative rods are common inhabitants of plants and they have been recovered from soil, water, and milk.
They are growth-promoting or symbionts in the rhizosphere of several crop plants.
21 S. maltophila
is regarded as the second most common nosocomial bacterium after Pseudomonas aeruginosa (see
reference 21). One species, S. rhizophila, has been used to control fungal diseases in plants (see
reference 57).
Vagococcus (va • go • coc’cus; wandering coccus). This genus was created to accommodate the group
N lactococci based on 16S sequence data.
11 They are motile by peritrichous flagella, are Gram positive
and catalase negative, and grow at 10
◦ C but not at 45
◦ C. They grow in 4% NaCl but not 6.5%, and no
growth occurs at pH 9.6. The cell wall peptidoglycan is Lys-d-Asp, and the mol% G + C is 33.6. At
least one species produces H 2 S. They are found on fish, in feces, and in water and may be expected
to occur on other foods.
11,47 Information on the phylogenetic relationship of the vagococci to other
related genera is presented in Figure 25–1.
Vibrio (vib’ri • o). These Gram-negative straight or curved rods are members of the family Vibrionaceae. Several former species have been transferred to the genus Listonella.
32 Several species cause
gastroenteritis and other human illness; they are discussed in Chapter 28. The mol% G + C content
of DNA is 38–51. (See reference 13 for environmental distribution.)
Weissella (Weiss’ella, after N. Weiss). This genus of lactic acid bacteria was established in 1993 in part
to accommodate the “leuconostoc branch” of the lactobacilli.
9 The seven species are closely related
Modern Food Microbiology
Serratia (ser • ra’ti • a). These Gram-negative rods that belong to the family Enterobacteriaceae are
aerobic and proteolytic, and they generally produce red pigments on culture media and in certain
foods, although nonpigmented strains are not uncommon. S. liquefaciens is the most prevalent of the
foodborne species; it causes spoilage of refrigerated vegetables and meat products. The mol% G + C
content of DNA is 53–59. Interestingly, a spore-forming S. marcescens isolate has been reported and
named S. marcescens subsp. sakuensis.
1
Shewanella (she • wa • nel’la). The bacterium once classified as Pseudomonas putrefaciens and later
as Alteromonas putrefaciens has been placed in this genus as S. putrefaciens. They are Gram-negative,
straight or curved rods, nonpigmented, and motile by polar flagella. They are oxidase positive and
have a mol% G + C of 44–47. The other three species in this genus are S. hanedai, S. benthica, and
S. colwelliana. All are associated with aquatic or marine habitats, and the growth of S. benthica is
enhanced by hydrostatic pressure.
14,32
Shigella (shi • gel’la). All members of this genus are presumed to be human enteropathogens; they
are discussed further in Chapter 26.
Sphingomonas (Sphin • go • monas). There are at least 33 species of this genus of Gram-negative
bacteria that typically produce yellow pigment, and which formerly were in the genus Flavobacterium.
They are found in water, on certain vegetables, and cause human disease.
58
Staphylococcus (staph • y • lo • coc’cus; grape-like coccus). These Gram-positive, catalase-positive
cocci include S. aureus, which causes several disease syndromes in humans, including foodborne
gastroenteritis. It and other members of the genus are discussed further in Chapter 23. The former
S. caseolyticus has been transferred to the new genus Macrococcus as M. caseolyticus.
29
Stenotrophomonas (Ste • no • tro • pho • mo’nas, a unit feeding on few substrates). These Gramnegative rods are common inhabitants of plants and they have been recovered from soil, water, and milk.
They are growth-promoting or symbionts in the rhizosphere of several crop plants.
21 S. maltophila
is regarded as the second most common nosocomial bacterium after Pseudomonas aeruginosa (see
reference 21). One species, S. rhizophila, has been used to control fungal diseases in plants (see
reference 57).
Vagococcus (va • go • coc’cus; wandering coccus). This genus was created to accommodate the group
N lactococci based on 16S sequence data.
11 They are motile by peritrichous flagella, are Gram positive
and catalase negative, and grow at 10
◦ C but not at 45
◦ C. They grow in 4% NaCl but not 6.5%, and no
growth occurs at pH 9.6. The cell wall peptidoglycan is Lys-d-Asp, and the mol% G + C is 33.6. At
least one species produces H 2 S. They are found on fish, in feces, and in water and may be expected
to occur on other foods.
11,47 Information on the phylogenetic relationship of the vagococci to other
related genera is presented in Figure 25–1.
Vibrio (vib’ri • o). These Gram-negative straight or curved rods are members of the family Vibrionaceae. Several former species have been transferred to the genus Listonella.
32 Several species cause
gastroenteritis and other human illness; they are discussed in Chapter 28. The mol% G + C content
of DNA is 38–51. (See reference 13 for environmental distribution.)
Weissella (Weiss’ella, after N. Weiss). This genus of lactic acid bacteria was established in 1993 in part
to accommodate the “leuconostoc branch” of the lactobacilli.
9 The seven species are closely related