Limits...
Appraisal of microbial evolution to commensalism and pathogenicity in humans.

Ghosh AR - Clin Med Insights Gastroenterol (2013)

Bottom Line: The human body is host to a number of microbes occurring in various forms of host-microbe associations, such as commensals, mutualists, pathogens and opportunistic symbionts.While this association with microbes in certain cases is beneficial to the host, in many other cases it seems to offer no evident benefit or motive.The present discussion examines this interaction while tracing the origins of this association, and attempts to hypothesize a possible framework of selective pressures that could have lead microbes to inhabit mammalian host systems.

View Article: PubMed Central - PubMed

Affiliation: Centre for Infectious Diseases and Control, Division of Medical Biotechnology, School of Biosciences and Technology, VIT University, India.

ABSTRACT
The human body is host to a number of microbes occurring in various forms of host-microbe associations, such as commensals, mutualists, pathogens and opportunistic symbionts. While this association with microbes in certain cases is beneficial to the host, in many other cases it seems to offer no evident benefit or motive. The emergence and re-emergence of newer varieties of infectious diseases with causative agents being strains that were once living in the human system makes it necessary to study the environment and the dynamics under which this host microbe relationship thrives. The present discussion examines this interaction while tracing the origins of this association, and attempts to hypothesize a possible framework of selective pressures that could have lead microbes to inhabit mammalian host systems.

No MeSH data available.


Related in: MedlinePlus

Possible selective pressures on primary anaerobes for sustainable environments. Selective pressure-like increases in O2 content in anaerobic environment, in deep soil, marine water, and so on lead to the evolution of microaerophilic, facultative anerobes, as well as facultative aerobes and obligate aerobes. Some facultative anaerobes later on found optimum living systems in the human gut due to constant association.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4020404&req=5

f2-cgast-6-2013-001: Possible selective pressures on primary anaerobes for sustainable environments. Selective pressure-like increases in O2 content in anaerobic environment, in deep soil, marine water, and so on lead to the evolution of microaerophilic, facultative anerobes, as well as facultative aerobes and obligate aerobes. Some facultative anaerobes later on found optimum living systems in the human gut due to constant association.

Mentions: In an environment where nutritional requirements are high and nutrients are short in supply, natural selection favored a host–microbe interaction where the microbes gained an ideal growth environment and the host gained nutrition, explaining why such relationships evolved in the first place.14 Thus, today’s microflora today help the human host in breaking down a variety of dietary compounds, while the bacteria in the intestine are provided with a warm protected nutrient rich environment. Changing food habits, habitat, of early primates could have guided the type of microbes that gained entry into the gut and the other anatomical niches, and thus could have evolved into a commensal from its free-living counterparts (Fig. 2). The gut normal microflora association is based on nutritional needs as that is seen among ruminating animals harboring a wide variety of microbes in their rumens.19,20 In the rumen, special bacteria ferment the vegetable proteins, carbohydrates (cellulose) and convert them into those usable by the animals. The rumen microflora ecosystem adapts to the diet consumed by the animal.16,21


Appraisal of microbial evolution to commensalism and pathogenicity in humans.

Ghosh AR - Clin Med Insights Gastroenterol (2013)

Possible selective pressures on primary anaerobes for sustainable environments. Selective pressure-like increases in O2 content in anaerobic environment, in deep soil, marine water, and so on lead to the evolution of microaerophilic, facultative anerobes, as well as facultative aerobes and obligate aerobes. Some facultative anaerobes later on found optimum living systems in the human gut due to constant association.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4020404&req=5

f2-cgast-6-2013-001: Possible selective pressures on primary anaerobes for sustainable environments. Selective pressure-like increases in O2 content in anaerobic environment, in deep soil, marine water, and so on lead to the evolution of microaerophilic, facultative anerobes, as well as facultative aerobes and obligate aerobes. Some facultative anaerobes later on found optimum living systems in the human gut due to constant association.
Mentions: In an environment where nutritional requirements are high and nutrients are short in supply, natural selection favored a host–microbe interaction where the microbes gained an ideal growth environment and the host gained nutrition, explaining why such relationships evolved in the first place.14 Thus, today’s microflora today help the human host in breaking down a variety of dietary compounds, while the bacteria in the intestine are provided with a warm protected nutrient rich environment. Changing food habits, habitat, of early primates could have guided the type of microbes that gained entry into the gut and the other anatomical niches, and thus could have evolved into a commensal from its free-living counterparts (Fig. 2). The gut normal microflora association is based on nutritional needs as that is seen among ruminating animals harboring a wide variety of microbes in their rumens.19,20 In the rumen, special bacteria ferment the vegetable proteins, carbohydrates (cellulose) and convert them into those usable by the animals. The rumen microflora ecosystem adapts to the diet consumed by the animal.16,21

Bottom Line: The human body is host to a number of microbes occurring in various forms of host-microbe associations, such as commensals, mutualists, pathogens and opportunistic symbionts.While this association with microbes in certain cases is beneficial to the host, in many other cases it seems to offer no evident benefit or motive.The present discussion examines this interaction while tracing the origins of this association, and attempts to hypothesize a possible framework of selective pressures that could have lead microbes to inhabit mammalian host systems.

View Article: PubMed Central - PubMed

Affiliation: Centre for Infectious Diseases and Control, Division of Medical Biotechnology, School of Biosciences and Technology, VIT University, India.

ABSTRACT
The human body is host to a number of microbes occurring in various forms of host-microbe associations, such as commensals, mutualists, pathogens and opportunistic symbionts. While this association with microbes in certain cases is beneficial to the host, in many other cases it seems to offer no evident benefit or motive. The emergence and re-emergence of newer varieties of infectious diseases with causative agents being strains that were once living in the human system makes it necessary to study the environment and the dynamics under which this host microbe relationship thrives. The present discussion examines this interaction while tracing the origins of this association, and attempts to hypothesize a possible framework of selective pressures that could have lead microbes to inhabit mammalian host systems.

No MeSH data available.


Related in: MedlinePlus