Increasing temperature and drought strongly affect the ability to grow crops Fungal-based soil food webs are common in extensively managed farming for example, grasslands and are better able to adapt to drought than bacterial-based food webs, which are common in intensive systems for example, wheat , A global assessment of topsoil found that soil fungi and bacteria occupy specific niches and respond differently to precipitation and soil pH, indicating that climate change would have differential impacts on their abundance, diversity and functions Aridity, which is predicted to increase owing to climate change, reduces bacterial and fungal diversity and abundance in global drylands Reducing soil microbial diversity reduces the overall functional potential of microbial communities, thereby limiting their capacity to support plant growth The combined effects of climate change and eutrophication caused by fertilizers can have major, potentially unpredictable effects on microbial competitiveness.
For example, nutrient enrichment typically favours harmful algal blooms, but a different outcome was observed in the relatively deep Lake Zurich Reducing phosphorus inputs from fertilizers reduced eukaryotic phytoplankton blooms but increased the nitrogen-to-phosphorus ratio and thus the non-nitrogen-fixing cyanobacterium Planktothrix rubescens became dominant In the absence of effective predation, annual mixing has an important role in controlling cyanobacterial populations.
However, warming increased thermal stratification and reduced mixing, thereby facilitating the persistence of the toxic cyanobacteria Climate change affects the occurrence and spread of diseases in marine and terrestrial biota Fig.
Understanding the spread of disease and designing effective control strategies requires knowledge of the ecology of pathogens, their vectors and their hosts, and the influence of dispersal and environmental factors Table 1. For example, there is a strong link between increasing sea surface temperatures and coral disease and, although the disease mechanisms are not absolutely clear for all the different syndromes, associations with microbial pathogens exist , , In particular, in some coral species, ocean warming can alter the coral microbiome, disrupting the host—symbiont equilibrium, shifting defensive mechanisms and nutrient cycling pathways that may contribute to bleaching and disease Ocean acidification may also directly cause tissue damage in organisms such as fish, potentially contributing to a weakened immune system that creates opportunities for bacterial invasion Anthropogenic climate change stresses native life, thereby enabling pathogens to increasingly cause disease.
The impact on aquaculture, food-producing animals and crops threatens global food supply. Human activities, such as population growth and transport, combined with climate change increase antibiotic resistance of pathogens and the spread of waterborne and vector-borne pathogens, thereby increasing diseases of humans, other animals and plants.
As sea stars are important predators of sea urchins, loss of predation can cause a trophic cascade that affects kelp forests and associated marine biodiversity , Given the effects of ocean warming on pathogen impacts, temperature monitoring systems have been developed for a wide range of marine organisms, including corals, sponges, oysters, lobsters and other crustaceans, sea stars, fish and sea grasses Forest die-off caused by drought and heat stress can be exacerbated by pathogens For crops, a variety of interacting factors are important when one is considering response to pathogens, including CO 2 levels, climatic changes, plant health and species-specific plant—pathogen interactions A broad range of microorganisms cause plant diseases fungi, bacteria, viruses, viroids and oomycetes and can, therefore, affect crop production, cause famines for example, the oomycete Phytophthora infestans caused the Irish potato famine and threaten food security An assessment of more than crop pests nematodes and insects and pathogens since found an expansion towards the poles that is attributable to climate change The spread of pathogens and the emergence of disease are facilitated by transport and introduction of species and are influenced by effects of weather on dispersal and environmental conditions for growth Climate change can increase the disease risk by altering host and parasite acclimation For ectotherms such as amphibians , temperature can increase susceptibility to infection, possibly through perturbation of immune responses , Monthly and daily unpredictable environmental temperature fluctuations increase the susceptibility of the Cuban tree frog to the pathogenic chytrid fungus Batrachochytrium dendrobatidis.
The effect of increasing temperature on infection contrasts with decreased growth capacity of the fungus in pure culture, illustrating the importance of assessing host—pathogen responses rather than extrapolating from growth rate studies of isolated microorganisms when evaluating the relevance of climate change Climate change is predicted to increase the rate of antibiotic resistance of some human pathogens Potential underlying mechanisms include elevated temperatures facilitating horizontal gene transfer of mobile genetic elements of resistance, and increased pathogen growth rates promoting environmental persistence, carriage and transmission Population growth, which amplifies climate change, is also an important factor in contributing to the development of resistance Vector-borne, foodborne, airborne, waterborne and other environmental pathogens may be particularly susceptible to the effects of climate change , , , Table 1.
For vector-borne diseases, climate change will affect the distribution of vectors and hence the range over which diseases are transmitted, as well as the efficiency with which vectors transmit pathogens.
Efficiency depends on the time between a vector feeding on an infected host and the vector becoming infectious itself. Certain vector-borne diseases, such as bluetongue, an economically important viral disease of livestock, have already emerged in Europe in response to climate change, and larger, more frequent outbreaks are predicted to occur in the future For certain waterborne infections by pathogenic Vibrio spp.
These changed conditions can promote the growth of Vibrio spp. Increasing sea surface temperatures also correlate with increases in Vibrio cholerae infections in Bangladesh , infections with several human-pathogenic Vibrio spp.
Malaria and dengue fever are two vector-borne diseases that are known to be highly sensitive to climate conditions, and thus their spatial distributions are expected to shift in response to climate change 4 , , Climate change can facilitate the spread of vector-borne pathogens by prolonging the transmission season, increasing the rate of replication of pathogens in the vector and increasing the number and geographic range of mosquitoes.
This is especially the case for Aedes aegypti , the major vector of dengue, Zika, chikungunya and yellow fever viruses, which is currently limited to tropical and subtropical regions because it cannot survive cold winters. In combination with other mosquito-borne diseases such as West Nile fever and Japanese encephalitis and tick-borne diseases such as Lyme disease , millions of people are predicted to be newly at risk under climate change 4 , , , , , Many infectious diseases, including several vector-borne and waterborne diseases, are strongly influenced by climate variability caused by large-scale climate phenomena such as the ENSO, which disrupts normal rainfall patterns and changes temperatures in about two thirds of the globe every few years.
Associations with ENSO have been reported for malaria, dengue fever, Zika virus disease, cholera, plague, African horse sickness and many other important human and animal diseases , , , , Adaptation of species to their local environment has been studied less in microorganisms than in animals including humans and plants, although the mechanisms and consequences of adaptation have been studied in natural and experimental microbial populations Viral, bacterial and fungal pathogens of plants and animals such as crops, humans and livestock adapt to abiotic and biotic factors such as temperature, pesticides, interactions between microorganisms and host resistance in ways that affect ecosystem function, human health and food security The cyclic feedback between microbial response and human activity is well illustrated by the adaptation patterns of pathogenic agricultural fungi The ability of fungal pathogens to expand their range and invade new habitats by evolving to tolerate higher temperatures compounds the threat fungal pathogens pose to both natural and agricultural ecosystems An improved understanding of microbial interactions would help underpin the design of measures to mitigate and control climate change and its effects see also ref.
For example, understanding how mosquitoes respond to the bacterium Wolbachia a common symbiont of arthropods has resulted in a reduction of the transmission of Zika, dengue and chikungunya viruses through the introduction of Wolbachia into populations of A. In agriculture, progress in understanding the ecophysiology of microorganisms that reduce N 2 O to harmless N 2 provides options for mitigating emissions , The use of bacterial strains with higher N 2 O reductase activity has lowered N 2 O emissions from soybean, and both natural and genetically modified strains with higher N 2 O reductase activity provide avenues for mitigating N 2 O emissions Manipulating the rumen microbiota and breeding programmes that target host genetic factors that change microbial community responses are possibilities for reducing methane emission from cattle.
In this latter case, the aim would be to produce cattle lines that sustain microbial communities producing less methane without affecting the health and productivity of the animals Fungal proteins can replace meat, lowering dietary carbon footprints Biochar is an example of an agricultural solution for broadly and indirectly mitigating microbial effects of climate change.
Biochar is produced from thermochemical conversion of biomass under oxygen limitation and improves the stabilization and accumulation of organic matter in iron-rich soils Biochar improves organic matter retention by reducing microbial mineralization and reducing the effect of root exudates on releasing organic material from minerals, thereby promoting growth of grasses and reducing the release of carbon Such major developments of constructed wetlands would require the characterization and optimization of their core microbial consortia to manage their emissions of greenhouse gases and optimize environmental benefits Microbial biotechnology can provide solutions for sustainable development , including in the provision for example, of food and regulation for example, of disease or of emissions and capture of greenhouse gases of ecosystem services for humans, animals and plants.
Microbial technologies provide practical solutions chemicals, materials, energy and remediation for achieving many of the 17 United Nations Sustainable Development Goals, addressing poverty, hunger, health, clean water, clean energy, economic growth, industry innovation, sustainable cities, responsible consumption, climate action, life below water, and life on land 6 Box 1. Galvanizing support for such actions will undoubtedly be facilitated by improving public understanding of the key roles of microorganisms in global warming, that is, through attainment of microbiology literacy in society 7.
Microorganisms make a major contribution to carbon sequestration, particularly marine phytoplankton, which fix as much net CO 2 as terrestrial plants. For this reason, environmental changes that affect marine microbial photosynthesis and subsequent storage of fixed carbon in deep waters are of major importance for the global carbon cycle. Microorganisms also contribute substantially to greenhouse gas emissions via heterotrophic respiration CO 2 , methanogenesis CH 4 and denitrification N 2 O.
Many factors influence the balance of microbial greenhouse gas capture versus emission, including the biome, the local environment, food web interactions and responses, and particularly anthropogenic climate change and other human activities Figs 1 — 3.
Human activity that directly affects microorganisms includes greenhouse gas emissions particularly CO 2 , CH 4 and N 2 O , pollution particularly eutrophication , agriculture particularly land usage and population growth, which positively feeds back on climate change, pollution, agricultural practice and the spread of disease.
Human activity that alters the ratio of carbon uptake relative to release will drive positive feedbacks and accelerate the rate of climate change. By contrast, microorganisms also offer important opportunities for remedying human-caused problems through improved agricultural outcomes, production of biofuels and remediation of pollution. Addressing specific issues involving microorganisms will require targeted laboratory studies of model microorganisms Box 2. Mesocosm and in situ field experiments are particularly important for gaining insight into community-level responses to real environmental conditions.
Effective experimental design requires informed decision-making, involving knowledge from multiple disciplines specific to marine for example, physical oceanography and terrestrial for example, geochemistry biomes. To understand how microbial diversity and activity that govern small-scale interactions translate to large system fluxes, it will be important to scale findings from individuals to communities and to whole ecosystems.
Earth system modellers need to include microbial contributions that account for physiological and adaptive evolutionary responses to biotic including other microorganisms, plants and organic matter substrates and abiotic including mineral surfaces, ocean physics and chemistry forcings.
We must improve our quantitative understanding of the global marine and soil microbiome. To understand biogeochemical cycling and climate change feedbacks at any location around the world, we need quantitative information about the organisms that drive elemental cycling including humans, plants and microorganisms , and the environmental conditions including climate, soil physiochemical characteristics, topography, ocean temperature, light and mixing that regulate the activity of those organisms.
The framework for quantitative models exists, but to a large extent these models lack mechanistic details of marine and terrestrial microorganisms. The reason for this omission has less to do with how to construct such a model mathematically but instead stems from the paucity of physiological and evolutionary data allowing robust predictions of microbial responses to environmental change. A focused investment into expanding this mechanistic knowledge represents a critical path towards generating the global models essential for benchmarking, scaling and parameterizing Earth system model predictions of current and future climate.
Extant life has evolved over billions of years to generate vast biodiversity, and microbial biodiversity is practically limitless compared with macroscopic life.
Biodiversity of macroscopic organisms is rapidly declining because of human activity, suggesting that the biodiversity of host-specific microorganisms of animal and plant species will also decrease. However, compared with macroscopic organisms, we know far less about the connections between microorganisms and anthropogenic climate change. We can recognize the effects of microorganisms on climate change and climate change on microorganisms, but what we have learned is incomplete, complex and challenging to interpret.
It is therefore not surprising that challenges exist for defining causes and effects of anthropogenic climate change on biological systems. Nevertheless, there is no doubt that human activity is causing climate change, and this is perturbing normal ecosystem function around the globe Box 1. Across marine and terrestrial biomes, microbially driven greenhouse gas emissions are increasing and positively feeding back on climate change.
Irrespective of the fine details, the microbial compass points to the need to act Box 2. Ignorance of the role of, effects on and feedback response of microbial communities to climate change can lead to our own peril. An immediate, sustained and concerted effort is required to explicitly include microorganisms in research, technology development, and policy and management decisions.
Microorganisms not only contribute to the rate of climate change but can also contribute immensely to its effective mitigation and our adaptation tools. Greater recognition that all multicellular organisms, including humans, rely on microorganisms for their health and functioning; microbial life is the support system of the biosphere.
The inclusion of microorganisms in mainstream climate change research, particularly research addressing carbon and nitrogen fluxes. Experimental design that accounts for environmental variables and stresses biotic and abiotic that are relevant to the microbial ecosystem and climate change responses. Investigation of the physiological, community and evolutionary microbial responses and feedbacks to climate change.
A focus on microbial feedback mechanisms in the monitoring of greenhouse gas fluxes from marine and terrestrial biomes and agricultural, industrial, waste and health sectors and investment in long-term monitoring. Incorporation of microbial processes into ecosystem and Earth system models to improve predictions under climate change scenarios. The development of innovative microbial technologies to minimize and mitigate climate change impacts, reduce pollution and eliminate reliance on fossil fuels.
The introduction of teaching of personally, societally, environmentally and sustainability relevant aspects of microbiology in school curricula, with subsequent upscaling of microbiology education at tertiary levels, to achieve a more educated public and appropriately trained scientists and workforce. A recognition that all key biosphere processes rely on microorganisms and are greatly affected by human behaviour, necessitating integration of microbiology in the management and advancement of the United Nations Sustainable Development Goals.
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Pachiadaki, M. Major role of nitrite-oxidizing bacteria in dark ocean carbon fixation. Grzymski, J. As an example, a healthy gut microbiota includes two main groups of bacteria called Firmicutes and Bacteroidetes, but it has been shown that, in the guts of obese people, Bacteroidetes are almost absent.
It is known that a healthy microbiota which means a microbiota with a huge bacterial diversity, including plenty of good microbes contributes to our health Figure 3. Do you want to be healthy? Then you need to take care of your friendly intestinal bacteria. How can you do that? Over the last few decades, many of the diseases mentioned above have been increasing. Many of these problems are related to changes in the types of food we eat [ 5 ].
We eat a lot of sugar in things like cakes, biscuits, brownies, sweet jellies, and white bread, and we also eat a lot of burgers, meat with fat, and sauces, which, in excess, are not good for our health.
These foods are also not good for some of our intestinal microbiota. Some of our microbes need veggies, fibers from beans, chickpeas, cereals, dark bread, seeds, and roots.
These types of foods are called prebiotics and they help the growth of the microbiota, feeding bacteria that are able to break down this type of food into the nutrients that can be used by the human body to improve our health.
We cannot digest some types of food properly if we do not have our tiny friends in our guts. Therefore, we do not want these good bacteria to die, because they are important to our health balance. The reduction of these good bacteria will allow the growth of the not-so-good bacteria that can eventually cause health problems.
Probiotics can help you replace the lost good microbiota. Probiotics are live bacteria that are good for us, that balance our good and bad intestinal bacteria, and that aid in digestion of food and help with digestive problems, such as diarrhea and bellyache. Bacteria that are examples of probiotics are Lactobacilli and Bifidobacterium.
You can find probiotics in some foods, such as yogurts, sourdough bread, buttermilk, and sour pickles. Some infant formulas are also supplemented with probiotics, despite the fact that we do not really know yet how helpful they are in diseases of babies.
Antibiotics are medicines we take to treat infections caused by bacteria. Antibiotics are not active against infections by fungi or viruses.
So, do antibiotics kill our good bacteria friends too? Yes, they do [ 3 ]. However, if we have a bacterial infection, we have to treat it, so in many cases we must take antibiotics.
Be sure to only take antibiotics when your doctor says you really need to, and take them during the time he advises. You do not need an antibiotic to treat a cold or the flu, because these diseases are caused by viruses.
People who take a lot of antibiotics may get sick because the antibiotics destroy lots of the bacteria in their bodies, including the good ones. When lots of the bacteria in the gut are killed, the gut then has more free space and available food for the bad bacteria, which can then multiply. When these bad bacteria reach higher numbers, they can sometimes cause disease. Estimates have fluctuated, but the most recent study to consider the matter — which appeared in PLOS Biology in — suggests that we likely have about as many microorganisms in and on our bodies as we do human cells.
In addition to bacteria and viruses, these microorganisms include archaea , primitive organisms with no nucleus, and eukaryotic microorganisms, or eukarya, a type with a nucleus that protects its chromosomes. All of these together make up various microbiota : communities of microorganisms present at different sites on or in the human body.
The various microbiota make up the human microbiome: the totality of microorganism communities spread around the human body. Collections of microorganisms in different areas play a crucial role in helping maintain our health — though to do so, the numbers of various types of bacteria, fungi, and other microorganisms have to remain in perfect balance.
When that balance is tipped and, for instance, one bacterial species overpopulates, this can lead to infections and other health problems. This feature describes the various organisms that make their homes in the gut, mouth, vagina and uterus, penis, skin, eyes, and lungs.
The most talked-about environment for colonizing microorganisms, especially bacteria, is the human gut. Research has also suggested that gut bacteria moderate the connection between the gut and the brain through an interaction with the enteric nervous system and other mechanisms, which may be hormonal or immunological.
Others are Actinobacteria , Proteobacteria , Fusobacterua , and Verrucomicrobia. These include some familiar bacterial groups, or genera, from the Firmicutes phyla, such as Lactobacillus , which is known for its positive impact on health.
On the other hand, some Firmicutes species can rapidly cause illness if they overgrow — such as Staphylococcus aureus and Clostridium perfringens. The Proteobacteria phylum includes some well-known pathogenic groups, such as Enterobacter, Helicobacter , Shigella , and Salmonella bacteria, as well as Escherichia coli.
Meanwhile, the Actinobacteria phylum includes the Bifidobacterium bifidum species, which is generally beneficial for healthy individuals. This list, however, is by no means exhaustive. There are around 2, bacterial species in the human gastrointestinal tract, according to compiled data. If some of these names sounded uncomfortably familiar, it is because many of these bacteria can cause infection if they over-colonize. And some strains can infect the gut through food that has gone bad or contact with unclean surfaces.
Some strains of E. But gut bacteria can typically be strong allies in health maintenance, and specialists continue to study the many ways in which these microorganisms help keep us in good form.
Elizabeth Hohmann in an interview with Harvard Medical School. Other microorganisms present in the gut are viruses, but not the ones that typically cause illness. Still, much about them remains poorly understood. The oral microbiota contains 12 bacterial phyla — Firmicutes , Fusobacteria , Proteobacteria , Actinobacteria , Bacteroidetes , Chlamydiae , Chloroflexi , Spirochaetes , SR1 , Synergistetes , Saccharibacteria , and Gracilibacteria — with multiple species, named or unnamed.
But the mouth also houses other microorganisms, namely protozoa, the most common of which are Entamoeba gingivalis and Trichomonas tenax , as well as fungi and viruses. To cause an infection, microbes must enter our bodies. The site at which they enter is known as the portal of entry. An infection can be seen as a battle between the invading pathogens and host.
How does the immune system work? Homepage Why Microbiology Matters What is microbiology? Microbes and the human body Microbes and disease.
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