Chapter 32

The average adult carries ___ times more microbial cells than human cells. interactions between hosts and microbes are ___, such that microorganisms colonize a specific site on the host that meets its physiological needs.

10 dynamic

A very acidic pH of the gastric contents kills most microorganisms. as a result, the stomach usually contains less than ___ viable bacteria per milliliter of ___ fluid. microorganisms may survive if they pass rapidly through the smash or if the organisms ingested with food are particularly resistant to ___ pH.

10 gastric gastric

the adult human is covered with approximately 2m^2^ of skin. it has been estimated that this surface area supports about ___ bacteria. microorganisms living on or in the skin can be either ___ or ____ microbiota. ____ organisms normally grow on or in the skin. their presence becomes fixed in well0defined distribution patterns. those that are temporarily present are ____ microorganisms. ___ usually do not become firmly entranced and are typically unable to ____.

10^12^ normal transient resident transient transients multiply

Which of the following would you expect to find in the tonsilar crypts? A. Micrococcus B. Staphylococcus C. Streptococcus D. Neisseria

A. Micrococcus

When Nitrobacter utilizes nitrite produced from ammonia by Nitrosomonas to obtain energy by converting the nitrite to nitrate, the relationship between the two organisms is A. commensal. B. amensal. C. mutual. D. parasitic.

A. commensal.

Microbes such as Lactobacillus acidophilus colonize the human vagina by fermenting A. glycogen. B. glucose. C. lactose. D. sucrose.

A. glycogen.

Gram-positive bacteria such as Propionibacterium acnes limit the growth of gram-negative bacteria and some fungi on the human skin by converting secreted __________ to compounds with antimicrobial activity. A. lipids B. organic acids C. salts D. urea

A. lipids

Human sweat has antimicrobial activity due to A. production of an antimicrobial peptide called cathelicidins. B. competition with normal sweat gland flora. C. production of low molecular weight compounds that maintain an alkaline pH. D. production of low molecular weight compounds that chelate free iron.

A. production of an antimicrobial peptide called cathelicidins.

Any microorganism that spends a portion of its life associated with another organism of a different species is engaged in A. symbiosis. B. synergy. C. parasitism. D. commensalism.

A. symbiosis.

In commensalism A. the host and commensal can be separated and remain viable. B. the commensal is metabolically dependent on the host. C. the host provides some factor that the commensal cannot get otherwise. D. the host and commensal cannot be separated and remain viable and the commensal is metabolically dependent on the host. E. all of these.

A. the host and commensal can be separated and remain viable.

A bacterial genus that is found in large numbers in the intestinal tract of breast-fed infants is A. Bacteroides. B. Bifidobacteria. C. Escherichia. D. Doderlein's bacillus.

B. Bifidobacteria.

____________ arises when different microbes within a population or community try to acquire the same resource. A. Amensalism B. Competition C. Disruption D. Syntropism

B. Competition

Under normal circumstances, the microbiota of the skin is kept in check by A. a high pH (above 8). B. a slightly acidic pH. C. phagocytic activity. D. excessive moisture.

B. a slightly acidic pH.

A physical relationship where an organism hosts more than one symbiont is known as a A. clade. B. consortium. C. partnership. D. cojoining.

B. consortium.

Which of the following is not a category of symbiosis? A. mutualism B. phoresis C. commensalism D. parasitism

B. phoresis

A species of bacterium associated with the oil glands of the skin belongs to the genus A. Staphylococcus. B. Pityrosporum. C. Propionibacterium. D. Pityrosporum.

C. Propionibacterium.

Microbiota of the skin are most likely to be found A. where there is little moisture. B. where the pH of the skin secretions is below 4 C. in association with oil and sweat glands. D. all of the choices

C. in association with oil and sweat glands.

Methanogens are always engaged in relationships with other microbes because methane production requires A. removal of oxygen from the environment by another microbe. B. energy provided by another microbe. C. interspecies hydrogen transfer. D. none of the choices

C. interspecies hydrogen transfer.

The filamentous bacteria that grow on the dorsal surface of certain polychaete worms A. fend off potential predators with toxins. B. carry out photosythesis. C. may provide the worm with protection from toxic metals. D. all of the choices

C. may provide the worm with protection from toxic metals

__________ enzymes catalyze the hydrolysis of beta (1-4) linkages between successive D-glucose residues of cellulose.

Cellulase

___________ is a beneficial relationship similar to mutualism, in which the relationship is not obligatory.

Cooperation

Which of the following would you not find in the nasopharynx? A. Streptococcus pneumoniae B. Neisseria meningitidis C. Haemophilus influenzae D. Branhamella catarrhalis

D. Branhamella catarrhalis

Which of the following areas of the human body is(are) not normally free of microorganisms? A. respiratory tract B. intestinal tract C. eyes D. all of the choices

D. all of the choices

In mutualism A. the mutualist is dependent on the host. B. a reciprocal benefit accrues to both partners. C. the partners will not survive separately in many cases. D. all of these

D. all of these

The lungs are protected from microorganisms by A. the ciliated epithelial cells. B. lysozyme in mucus. C. phagocytic action of alveolar macrophages. D. all of these

D. all of these

A unidirectional process where a specific compound released by one organism has a negative effect on another organism is called A. predation . B. commensalism. C. negative cooperation. D. amensalism.

D. amensalism.

Microorganisms commonly associated with the human body are traditionally referred to as the A. normal microbial flora. B. normal microbes. C. normal microbiota. D. normal microbial flora or the normal microbiota

D. normal microbial flora or the normal microbiota

When members of the normal microbiota of the human body become pathogenic and produce disease under certain circumstances, they are referred to as ______________ pathogens. A. partial B. conditional C. occasional D. opportunistic

D. opportunistic

Escherichia coli is the most prevalent bacterium found in the colon.

FALSE

In the host-parasite relationship, it is advantageous for the parasite to disable and kill its host as quickly as possible.

FALSE

Many anaerobic gram-negative bacteria are normally found in the duodenum.

FALSE

The lower genitourinary tract is usually free of microorganisms.

FALSE

The lower respiratory tract has a normal microbiota.

FALSE

The skin surface (epidermis) is a very favorable environment for colonization by microorganisms.

FALSE

When two different microbes are engaged in a cooperative relationship, they do as well when living separately as they do when living together.

FALSE

microorganisms commonly associated with the human body are known as the ___ ____, because specific microbes have been routinely cultured from specific locations on the human host. (e.g. ____ and ____ on the skin, ____ in the colon, and ___ in the mouth. )

Normal microbiota stapyhlococci diphtheroids coliforms streptococci

Coral bleaching where the photosynthetic endosymbiont is lost or becomes non-functional can be caused by temperature increases as small as 2C.

TRUE

Insects frequently contain bacteria in their cytoplasm, and these bacteria form a mutualistic association with their host.

TRUE

The average adult carries 10 times more microbial cells (1014) than human cells (average about 1013).

TRUE

The oral cavity of humans normally becomes colonized with microorganisms within hours after birth.

TRUE

commensalistic associations occur when one microbial group modifies the environment to make it bettie suited for another organism. the synthesis of ___ waste product during ____ stimulates the proliferation of more acid-tolerant microorganisms, which may be only a minor part of the microbial community at ____ pH. a good example is the succession of microorganisms during milk spoilage. ____ formation provides another example. the ____ of a newly exposed surface by one type of microorganisms to attach to the microbial modified surface.

acidic fermentation neutral biofilm colonization

Members of the ____ genus Bifidobacteria represent more than ___% of the culturable ____ bacteria in breast-fed infant with members of Enterobacteriaceae and enterococci in smaller proportions. these data also suggest that human milk may act as a selective medium for ____ bacteria, as bottle-fed babies appear to have a much smaller proportion of ____ bifidobacteria.

actinobacterial 90% intestinal nonpathogenic intestinal

furthermore, bifidobacteria appear to be able to synthesize all ___ ___ and other required growth factors from simple nutrients such as ___ and inorganic sources of nitrogen, sulfur, and phosphorus. this bifidobacteria are well adapted for growth in the ___ environment, which has very ___ concentrations of these nutrients.

amino acids glucose colonic low

when the first teeth erupt, ____ become dominant due to the ___ nature of the space between the teeth and the gums. as the teeth grow, Streptococcus parasanguis and S. mutants attach to their ___ surfaces. S. salvers attaches to the ___ and ___ epithelial surfaces and colonizes the saliva. These streptococci produce a ___ and various other adherence factors that enable them to attach to oral surfaces.

anaerobes anoxic enamel buccal gingival glycocalyx

individuals who's microflora are dominated by Bacterides or Ruminococcus tend to have a diet right in ____ protein and ___ fats, while those who consume a largely ____-based diet host a large population of Prevotella.

animal saturated plant

- ____ are quite numerous in the colon and influence the host in a variety of ways. for instance their ___ degrade complex carbohydrates such as hemicellulose and pectin that have traditionally been considered ____. together with bifidobacteria, they are required for normal development of the ___ ___ ___ __ (GALT_, an essential component of host defense against pathogens. -cells of the SFB phylotype adhere tightly to host gut epithelial cells where they are needed for the development of __-__ cells.

bacteroidetes exoenzymes indigestible gut associated lymphoid tissue T-helper

in both predation and parasitic, the relationship between two organisms is ____ for one and ____ for the other. however, parasitism involves ____, at least temporarily, between host and ____. ____ may involve nutrient acquisition, physical maintenance in or on the host or both. the parasite must reside in the host for some period of time because if it kills the host immediately upon ____, the microbe will be unable to reproduce to sufficient numbers to ensure ____ of a new host.

beneficial harmful coexistence parasite coexistence invasion colonization

the inability of either partner to grow without the other indicates that the two organisms underwent ____; that is, they have ____ together.

coevolution evolved

one method for determining the impact of microorganisms routinely cultured form humans is to evaluate the consequences of their ___ in the ___ of other organisms. this is accomplished using ___ animals, born by cesarean delivery and reared in ___ environments. these animals (usually ___) provide suitable experimental models for investigating the interactions between the vertebrate host and its microbiota. comparing animals possessing normal microbiota (____ animals) with germ free animals allowed scientists to explore many of the complex relationship between microorganisms, hosts, and specific environments.

colonization absence germfree sterile mice conventional

_____ a relationship in which one symbiont, the ____, benefits, while the host is neither harmed nor helped. this is a ____ process. the spatial proximity of the two partners permits the commensal to feed on substance captured or ingested by the ___, the commensal often obtains shelter by living either on or in the host. the commensal is not directly ___ on the host's ____, so when it is separated from the host experimentally, it can survive without the addition of factors of the host origin.

commensalism commensal unidirectional host dependent metabolism

opportunistic microorganisms often cause disease in compromised hosts. a ___ ___ is seriously debilitated and has a lowered ____ to infection. there are many uses of this condition including malnutrition, alcoholism, cancer, diabetes, leukemia, another infectious disease, trauma from surgery or an injury an altered normal microbiota from the prolonged use of ___ and immunosuppression by various factors (e.g.. HIV)

compromised host resistance antibiotics

a number of studies suggest that the ___ and ___ of the adult microbiota result from a succession of microbial consortia that begins to form at ___ but it heavily influenced by genetic, developmental change, diet (high ___ vs, high __ vs. high ___ content), Personal hygiene, anatomical site and "life events".

diversity richness birth protein fat carbohydrate content

In general, bacteria diversity is greatest at ___ ___ (forearm, buttocks, hands) harboring a mixed representation of gram-negative and gram- positive. ___ areas, exhibit ___ diversity supporting mostly members of ___ and ___, in addition to low numbers of other bacteria. the skin surfaces with the ___ bacterial diversity are the oily ____ sites, (forehead, behind the ear and the back) where members of ____ dominate.

dry sites moist less Firmicutes Actinobacteria lowest sebaceous Actinobacteria

the ___ contains few microorganisms because of the combined influence of the stomachs acidic juices and the ___ action of ___ and ___ secretions that are added here. of the bacteria present, Gram-___ cocci and rods comprise most of the microbiota.

duodenum inhibitory bile pancreatic positive

the small intestine is divided into three anatomical areas: ___, ___, and ___.

duodenum jejunum ileum

microorganisms can associate physically with their hosts in a variety of ways. the micro can be located on the surface of the host, as an ____, or the microbe can be located within the host, as an ____. sometimes an organism hosts more than one symbiont: this is described as a ____. these physical associations can be ___, ___ or ___.

ectosymbiont endosymbiont consortium intermittent cyclic permanent

A relationship in which one organism is found on the surface of another is referred to as a(n) ___________.

ectosymbiosis

metagenomic evaluations of intestinal bacteria collected from infants and their caregivers suggest that bacteria colonize the ____ tract in a variable and chaotic manner with a few species appearing, disappearing and reappearing during the first few months of life. the metagenomic profile of ___ bacteria in adults includes 60%- 80% ____, 20-40% ___ and proteobacteria. interestingly, some studies suggest that humans may be divided into at least ___ categories based on the predominant genus of ___ bacteria.

gastrointestinal colonic firmicutes bacteriodetes three gut

One goal of the Human Microbiome Project is to sort out the impact of all these microbes and the genes they express on human ___ and ___.

health disease

a number of interesting recent reports confirm the impact of normal microbiota on human health. a few of note include: - the presence of relatively ___ number of ___ ___ is strongly correlated with obesity and type __ diabetes. -the ability to more easily complete stressful tasks is observed in ___ mice colonized with only Lactobacillus rhamnosus when compared to control mice. the bacteria-fed mice have altered ____ receptors in the brain, which may account for ___ anxiety. -propionate and acetate, produces as ___ products of ___ by colonic bifidobacteria help modulate ____. Propionate upregulate ___ cells of the adaptive immune system, influencing their ability to recognize foreign materials. conversely, acetate helps ___ inflammation associated with colitis, arthritis, and even asthma. anti-inflammatory effects have also been ascribed to members of the genus Clostridium and the phylotype.

high gut firmicutes 2 germfree neurotransmitter lower end fermentation immunity T cells reduce

Enterococcus faecalis, lactobacilli, diphtheroids and the yeast Candida albicans are occasionally found in the ___. in the ___ portion of the small intestine (____) the microbiota begins to take on the characteristics of the ___ microbiota. it is within the ____ that the pH becomes more alkaline. as a result ____ Gram-negative bacteria and members of the family Enterobacteriaceae become established.

jejunum dital ileum colon ileum anaerobic

the upper urinary tract (___, ___, and ___ ___) is usually ___ of microorganisms. in both males and females, a few common bacteria usually are cultured from the ___ portion of the urethra. In the male, metagenomic sequencing also suggests several anaerobic gram -____ bacteria are present. In contrast, the adult female genital tract, because of its large ___ ___ and ___ secretions, has a complex microbiota that constantly changes with a woman's ___ cycle. the cultural microorganisms are ___-tolerant. they ferment ___ produced by the ___ epithelium, forming lactic acid.

kidneys ureters urinary bladder free distal negative surface area mucus menstrual acid glycogen vaginal

the large intestine or colon has the ____ microbial community in the body. microscopic counts of feces approach 10^12^ organisms per gram wet weight. over 400 different bacterial species have been isolated from human ___. these microorganisms consist primarily of ____, gram-negative bacteria and gram-positive rods. however, ____ sequencing data estimate approximately 12,000 bacterial genera to be present in the ___. not only are the vast majority of the microorganisms anaerobic, but many different species are present in large numbers.

largest feces anaerobic metagenomic colon

mutualistic associations are common between ____ and ____ in part because insects often consume ___ ___ or ___ fluids lacking essential vitamins and ___ ___. these are provided by bacterial symbionts in exchange for a secure habitat and ample ___.

microbes insects plant sap animal amino acids nutrients.

the term ____ was coined to define all the microbes associated with the healthy host. this includes those that normally inhabit the skin, nose, ___, digestive tract and ___.

microbiome mouth vagine

while an adult's microbiota is relatively stable over time, the microbiota is highly variable from person to person and at different sites within the same person. in other words, there are relatively few microorganisms common to all humans, each human has a unique ___. based on ___ rRNA metagenomic sequencing, bacteria common to human skin and the mucosal surfaces of the ___ and ___ tracts appear to represent 5 phyla: actinobacteria, bacteroidetes, firmicutes, fusobacteria and proteobacteria. despite limited diversity at this ____ level, each phylum is represented by an enormous number of species. furthermore, different proportions of these 5 phyla assemble at various human sites and change in response to various ___ , until a stable population of microorganisms is established.

microbiota 16S oral gastrointestinal taxonomic stressors

____ defines the relationship in which some reciprocal benefit accrues to both partners. this is an *obligatory relationship* in which the ___ and the ____ are dependent on each other.

mutualism mutualist host

The three types of symbiosis we need to know are:

mutualism, parasitism, commensalism

___ pathogens are adapted to the noninvasive mode of life defined by the environment in which they live. if they are removed from their environment and introduced into different tissues or the bloodstream, ____ can result.

opportunistic disease

soon after an infant is born, the mouth is colonized by microorganisms from the surrounding environment. most microorganisms that initially invade the ___ ___ are ____ and obligate anaerobes.

oral cavity aerobes

A _________ is any disease-producing microorganism.

pathogen

a ___ is any disease-causing microorganism.

pathogen

although the normal microbiota offer some protection from invading microorganisms, its members may themselves become ___ and produce disease under certain circumstances they then are termed ___ ___ or ___.

pathogenic opportunistic microorganisms pathogens

____ is the ability to produce pathologic changes or disease.

pathogenicity

various physiological processes move the microbiota through the colon so an adult elinates about 3 X 10^13^ microorganisms daily. these processes include ___, ____ of the surface epithelial cells to which microorganisms are attached, and continuous flow of ___ that carries adhering microorganisms with it. To maintain ___, the body must continually ___ lost microorganisms with it. the bacterial population in the human ___ usually doubles once or twice a day. under normal conditions, the resident microbial community is self-regulating. ___ and ____ between different microorganisms and between the microorganisms and their host serve to maintain a status quo.

peristalsis desquamation mucus homeostasis replace colon competition mutualism

An example of microbial ___________ is the ability of Vampirococcus to attach to the outer membrane of its prey and then secrete degradative enzymes that result in the release of the prey's cytoplasmic contents.

predation

The loss of genetic information no longer needed for an intracellular existence by an obligate parasite is called genomic _____________.

reduction

the anatomy and physiology of the skin varies from one part of the body to another, and the normal ____ microbiota reflects these ____. the skin ___ or ____ has a slightly ___ pH, a high concentration of ___ ___, a lack of ___ in many areas. the skin surface can be divided into three environmental niches: ___, ___, and ___ (Containing sebum).

resident variations surface epidermis acidic sodium chloride moisture dry moist sebaceous

Acquistion of a normal microbiota represents a ____ process, where a niche may depend on ___ ___, surface properties, or secreted products. In humans each microbial niche is also related to age, gender, diet, nutrition and environment. for instance many microorganisms revealed by ___ ribosomal RNA sequencing can survive only within the ___ and nutritional unique environments established in or on the human host, thus preventing their culture in the lab.

selective cellular receptors 16S anoxic

the normal microbiota of the nose, pharynx and mouth are similar. just inside the nostrils, ___ ___ and ___ ___ are predominant cultural bacteria and are found in approximately the same numbers as on the skin of the ___>

staphylococcus aureus S. epidermidis face

because the fetus develops within the ___ uterus, the acquisition of the human microbiota begins at birth, when the newborn essentially colonized by microorganisms from its immediate environment. babies born vaginally acquire most of their microorganisms from their ___, whereas babies born by C-section acquire the microorganisms of their initial ____.

steril mother caretakes

commensalistic relationships between microorganisms include situations in which the waste product of one microorganism is a ____ for another species. One good example is ____- the oxidation of ___ ion to nitrate. ____ occurs in two steps: first, bacteria such as Nitromonas and certain crenatchaeotes oxidize ___ to nitrite; second, ____ is oxidized to ___ by Nitrobacter and similar bacteria. Nitrobacter benefit from their association with Nitrosomonas because they use ____ to obtain energy for growth.

substrate nitrification ammonium nitrification ammonium nitrite nitrate nitrite

most skin bacteria are found on ____ cells, colonizing ___ cells, or closely associated with the ___ and ___ glands. Secretions from these glands provide water, ___ ___, urea, electrolytes, and specific ___ ___ that serve at nutrients primarily for resident bacteria such as S. epidermis. The ___ glands secrete complex ___ that may be partially degraded by the enzymes from certain gram-positive bacteria. These bacteria usually are harmless, however, they are associated with the skin condition ___ ___. they convert ___ secreted by the oil glands to ___ ___ acids such as ___ acid that have strong antimicrobial activity against Gram-negative bacteria and some fungi.

superficial dead oil sweat amino acids fatty acids oil lipids acne vulgaris lipids unsaturated fatty oleic

when microbes interact with a larger organism, the microbe is usually called a ____ and a larger organism is its ___.

symbiont host

A close physical relationship between two different species that may or may not be beneficial is called __________.

symbiosis

mutually beneficial relationship between two organisms; simply describing two organisms living together.

symbiosis

an important aspect of many ____ relationship, including parasitism, is that over time, the ____, once is has established a relationship with the host, will discard excess, unused genomic information a process called ____ ____.

symbiotic symbiont genomic reduction

The term ____________ is used to describe a mutually beneficial association in which the growth of an organism is dependent on one or more growth factors, nutrients, or substrates provided by another organism in the same vicinity.

syntrophism

the upper and lower respiratory tracts do not have a normal microbiota. this is because microorganisms are removed in at least ___ ways. first, a continuous stream of ____ is generated by ___ cells. this entraps microorganisms, and the ____ epithelial cells continually move the entrapped microorganisms out of the respiratory tract. Second, _____ macrophages ____ and destroy microorganisms. finally a ____ effect is exerted by the enzyme ___, present in the nasal ___.

three mucus goblet ciliated alveolar phagocytize bactericidal lysozyme mucus

The term that refers to those microbes found as symbionts in a short relationship of a nongrowing nature is __________.

transient

The specialized structure in a tube worm in which endosymbiotic, chemolithotrophic bacteria live is called a(n) __________.

trophosome

some fatty acids are ___ and may have a strong odor. this is why many deodorants contain ____ substances that act ____ against gram-____ bacteria to reduce the production of volatile ___ ___ acids and body odor.

volatile antibacterial selectively positive unsaturated fatty

in many ways the mouth provides an ideal habitat for microbes. it has a ready supply of ___ and ___. it also has a ___ pH and moderate temperature. however, it subjects the normal microbiota to mechanical perturbations that can ___ microbes from the mouth. thus normal microbiota of the mouth consist of organisms that resist mechanical removal by ___ to duress such as the ___ and ___. these removal mechanisms include flushing of the oral cavity contents to the stomach where they are destroys by HCL and the continuous desquamation (shedding) of ___cells.

water nutrients neutral dislodge adhering gums teeth epithelial