A- @ Modern Food Microbiology 123456789.pdf

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1. Relationship s of Commo n Foodborn e Gener a
of Gram-Negativ e Bacteri a
Gram-negativ e bacteri a
Nonpigmente d
Pigmente d
Lactos e
i
Oxidas e
Negativ e
Positiv e
Negativ e
Positiv e
Oxidas e
Oxidas e
Negativ e
Positiv e
Negativ e
Positiv e
Acetobacter Acinetobacter Burkholderia Gluconobacter Hafnia Pantoea Proteus Providencia Pseudomonas Salmonella Serratia Shigella Yersinia
Aeromonas Alcaligenes Alteromonas Arcobacter Campylobacter Moraxella Plesiomonas Pseudomonas Psychrobacter Vibrio
Citrobacter Enterobacter Escherichia Klebsiella Pantoea Salmonella Serratia Yersinia
Aeromonas Alteromonas Plesiomonas Shewanella
Erwinia Pantoea Photobacterium Serratia Xanthomonas
Alteromonas (most )Chromobacterium Flavobacterium Photobacterium Vibrio Xanthomonas
Note: For details , consul t Bergey's Manual of Systematic Bacteriology.
APPENDIX A

2. Positive
Arthrobacter
Brevibacterium
Brochothrix
Corynebacterium
Kocuria
Kurthia
Listeria
Micrococcus
Planococcus
Propionibacterium
Staphylococcus
Negative
Bifidobacterium
Carnobacterium
Enterococcus
Erysipelothrix
Lactococcus
Lactobacillus
Lactosphera
Leuconostoc
Oenococcus
Pediococcus
Streptococcus
Tetragenococcus
Vagococcus
Weissella
APPENDIX B
Relationships of Common
Foodborne Genera of
Gram-Positive Bacteria
Note: For details, consult Bergey's Manual of Systematic Bacteriology.
ClostridiumA licyclobacillus
Bacillus
Paenibacillus
Sporolactobacillus
Catalase
Absent
Endospores
Anaerobes
Present
Aerobes
Gram-positive bacteria

3. The importance of biofilms to food safety and
spoilage warrants a better understanding of their
biology, structure, and function. Reviews of the
early history of our knowledge of these entities
have been presented by Carpentier and Cerf,4
Costerton et al.,6 and Zottola.13
A biofilm consists of the growth of bacteria,
fungi, and/or protozoa alone or in combination
bound together by an extracellular matrix that is
attached to a solid or firm surface. Common
examples include the slimy surfaces on rocks or
logs in bodies of running water, dental plaques,
and the slime layer on refrigerator-spoiled fresh
meats and poultry. They form on surfaces in large
part because nutrients are found in higher con-
centrations than in the open liquid. In labora-
tory studies, surface adherence is best in rich
media.2 Attachment is facilitated by the micro-
bial excretion of an exopolysaccharide matrix
sometimes referred to as a glycocalyx. Micro-
colonies form within this microenvironment in
a manner that leads to microbial communities
that allow water channels to form between and
around the microcolonies. The latter has been
likened to a primitive circulatory system where
nutrients are brought in and toxic by-products
are carried out. Microbial cells in liquids that
are not in a biofilm are in a planktonic (free float-
ing) state.
From the standpoint of food safety and spoil-
age, biofilms are important because of their ac-
cumulation on foods, food utensils, and surfaces;
and because of the difficulty of their removal.
While under natural conditions biofilms tend to
be composed of mixed cultures, pure culture sys-
tems are often used in laboratory studies. Some
of the solid surfaces employed to study
foodborne bacteria include floor sealant, glass
slides, nylon, polycarbonate, polypropylene, rub-
ber, stainless steel, and Teflon. Glass and stain-
less steel are widely used.
From the many studies that have been carried
out on biofilm formation in food environments,
the following summaries can be made:
• Although biofilm formation by single cul-
tures in rich media (e.g., tryptic soy broth)
may be evident after 24 hours when appro-
priate growth temperatures are used, three
to four days or more are necessary for maxi-
mum development. On glass slides in a cul-
ture medium for three days at 24°C, Lis-
teria monocytogenes grew to about log10
6-7/cm2.1
• Microorganisms in biofilms are consider-
ably more resistant to removal by commonly
used cleaning and sanitizing agents.
• In general, microorganisms in biofilms are
more difficult to destroy by lethal agents,
i.e., they are protected by the biofilm
matrix.57
• The attachment of a given pathogen to sur-
faces may be aided by the formation of a
mixed-culture biofilm.3912
Biofilms
APPENDIX C

4. • Microorganisms in biofilms may exhibit
different physiologic reactions than plank-
tonic forms, and the biofilm may contain
cells in the viable but nonculturable state.45
• The use of cleansers and sanitizers in com-
bination rather than singly appears to be
REFERENCES
1. Arizcun, C, et al. 1998. Effect of several decontami-
nation procedures on Listeria monocytogenes grow-
ing in biofilms. J. Food Protect. 61:731-734.
2. Blackman, LC, and XF. Frank. 1996. Growth of Lis-
teria monocytogenes as a biofilm on various food-pro-
cessing surfaces. J. Food Protect. 59:827-831.
3. Buswell, CM., et al. 1998. Extended survival and per-
sistence of Campylobacter spp. in water and aquatic
biofilms and their detection by immunofluorescent-
antibody and -rRNA staining. Appl. Environ.
Microbiol 64:733-741.
4. Carpentier, B., and O. Cerf. 1993. Biofilms and their
consequences, with particular reference to hygiene in
the food industry. J. Appl. Bacteriol. 75:499-511.
5. Chumkhunthod, R, et al. 1998. Rapid monitoring
method to assess efficacy of sanitizers against
Pseudomonas putida biofilms. J. Food Protect.
61:1043-1046.
6. Costerton, J.W., et al. 1994. Biofilms, the customized
microniche. J. Bacteriol. 176:2137-2142.
7. Frank, IF, and R.A. Koffi. 1990. Surface-adherent
growth of Listeria monocytogenes is associated with
more effective in removing biofilm
growth.111
• Not all strains of the same species are
equally capable of initiating biofilm forma-
tion;10 and surface attachment and biofilm
development are different processes.8
increased resistance to surfactant sanitizers and heat.
J. Food Protect. 53:550-554.
8. Kim, K. Y., and J.F. Frank. 1995. Effect of nutrients on
biofilm formation by Listeria monocytogenes on stain-
less steel. J. Food Protect. 58:24-28.
9. Leriche, V, and B. Carpentier. 1995. Viable but
nonculturable Salmonella typhimurium in single- and
binary-species biofilms in response to chlorine treat-
ment. J. Food Protect. 58:1186-1191.
10. Michiels, CW., et al. 1997. Molecular and metabolic
typing of resident and transient fluorescent
pseudomonad flora from a meat mincer. J. Food Pro-
tect. 60:1515-1519.
11. Oh, D.-H., and D.L. Marshall. 1996. Monolaurin and
acetic acid inactivation of Listeria monocytogenes at-
tached to stainless steel. J. Food Protect. 59:249-252.
12. Sasahara, K.C., and E.A. Zottola. 1993. Biofilm for-
mation by Listeria monocytogenes utilizes a primary
colonizing microorganism in flowing systems. J. Food
Protect. 56:1022-1028.
13. Zottola, E.A. 1994. Microbial attachment and biofilm
formation: A new problem for the food industry? Food
Technol. 48(7):107-114.

5. APPENDIX D
Grouping of the Gram-Negative
Asporogenous Rods, Polar-Flagellate,
Oxidase Positive, and Not Sensitive to
2.5 IU Penicillin, on the Results of
Four Other Tests
Behavior in the test of Hugh and Leifson
Oxidative Alkaline No action Fermentative
Green
fluorescent
diffusible
pigment
No diffusible
pigment
No diffusible
pigment
No diffusible
pigment
No diffusible
pigment
Acid, no gas in
glucose (some
strains form
traces of gas)
Acid, much
gas in glucose
at 20°
Sensitive to
the pteridine
compound
(0/129)
Insensitive to
the pteridine
compound
(O/129)
Pseudomonas,
Group I
Pseudomonas,
Group II
Pseudomonas,
Group III
Pseudomonas,
Group IV
Vibrio Aeromonas
Source: After J.M. Shewan, G. Hobbs, and W. Hodgkiss, 1960. A determinative scheme for the identification of certain
genera of gram-negative bacteria, with special reference to the Pseudomonadaceae. J. Appl. Bacteriol. 23:379—390.