Gut feelings: Why you should care about Probiotics

® 2013 Dannon Inc. All Rights Reserved

As more research is being conducted on the human microbiome, we are discovering the truth behind the saying ‘You are what you eat.’ In today’s society it is almost impossible to avoid the constant advertisement of food. Coupled with the thousands of diet plans, all claiming to be the best for you, it can be somewhat difficult to decide just what to eat for a snack. With labels such as Organic, Gluten-Free, Vegan, Free-Range, and Contains Probiotics on products in the grocery store, one can spend hours weighing the healthiest option.  

                                              Short Video on Probiotics

With more exposure and research being done on the gut microbiome, there has been an increase in advertisement of the products containing probiotics, such as yogurt.  Companies like Dannon, Yoplait and Stonyfield produce yogurt containing probiotics. The most heavily advertised is the Dannon Activia yogurt that promises to promote a healthy digestive system. What is it about probiotics that makes them beneficial to our health? Probiotics are live microorganisms in bacteria and yeast, they are believed to aid the digestive system. They also help fight against diseases and balance the microbial environment of the intestines. The yogurt Activia uses the probiotic culture Bifidobacterium lactis DN-173 010 because it is able to survive the digestive system. 

This figure (A) illustrates the amount of microbes in the human intestine, there are over 100 trillion microorganisms in the human body (4).

Recently, scientists have discovered that the health of gut microbiome has been shown to modulate brain activity. Previously, we only had knowledge of the signals sent from the brain to the gut and not vice versa. With the new information concerning our gut flora, we need to consider why the snacks we choose to eat are important to the overall health of the human microbiome as well as our brain activity rather than just simply our waistlines.                                                                                                                             

(B) displays the functions of the bacteria in the gut flora including the protective, structural and metabolic functions (6).

The signals that are sent from the gut to the brain were first observed in rodents, it was only in a recent study that it was also shown in humans. The study of the effects of probiotic yogurt on women was conducted at a UCLA research facility, the tests were also done with women eating no yogurt as well as women eating a dairy product that tasted like yogurt [2]. During the four-week study the women were asked to do a series of tasks to test reactivity to certain stimuli. The brain activity for regions that are associated with sensory and emotion were observed for the three groups of women. Surprisingly, the group of women consuming the probiotic yogurt showed a decrease in brain activity for emotions and sensations. The women who consumed the dairy product without probiotics had an increase in brain activity for these regions. Results from the group that had not consumed any yogurt also showed an increase in activity for the emotional and sensational regions.  Brain scans were also performed on the women when they were not completing a task and resting. Results from this scan show that women eating the probiotic yogurt had an increase in connectivity for the cognitive activity in the prefrontal cortex of the brain. Figure 1 displays a graph that shows the reduced activity to emotion attention task in different parts of the brain [1]. These are not showing a decrease in activity of the brain but simply encompass an overall difference in activity levels after intake of probiotics. The results from the study give more insight into the effect of food on the human microbiome. The yogurt a person chooses to eat for a snack will affect their brain activity in multiple areas. It is beneficial to understand the relationship of our diet and our gut flora as it pertains to brain function.

                                                                                                                                                        

                                                                             Figure 2 (1).

The more research conducted on the gut flora of our bodies can lead to treatment of many gastrointestinal diseases and other ailments associated with the gut. Each person has a different gut flora that is specific to the environment they are exposed to as well as the food they consume. A majority of the information about food that is available to consumers is primarily focused on the effects it has on their fitness. We often hear about the benefits of eating more vegetables and fruits in association with our waistlines but not as much as their effect on the microbial community of the human body. With obesity and the health problems that it causes beginning to become more apparent to people in the United States, companies have started advertising the health benefits of their products. While there are many food plans that can help you lose weight, many people are oblivious to the health of their microbial community. The human microbiome is an important part of digestive processes, production of vitamins, as well as maintaining the intestinal barrier (3). Each person can be thought of as an ecosystem in itself. A postivie relationship between the host and the community living in symbiosis is crucial to all ecosystems. The biggest threat to our ‘ecosystems’ is the use of antibiotics, which can be compared to the use of pesticides. Antibiotics allow us to fight off sickness but at the same time can do damage to our microbiome. There needs to be more research directed towards our microbiome and the effect medications will have on it in the long run. Scientists are only recently discovering the diseases that are caused by the imbalance in the human microbiome. Until more detailed information becomes available on our microbiome, we can start implementing practices such as consuming foods with probiotics, and living a healthier lifestyle to ensure the health of our ecosystems.

References:

1. Kirsten Tillisch, Jennifer Labus, Lisa Kilpatrick, Zhiguo Jiang, Jean Stains, Bahar Ebrat, Denis Guyonnet, Sophie Legrain-Raspaud, Beatrice Trotin, Bruce Naliboff, Emeran A. Mayer. Consumption of Fermented Milk Product with Probiotic Modulates Brain Activity. Gastroenterology, 2013; DOI: 10.1053/j.gastro.2013.02.043

2. University of California, Los Angeles (UCLA), Health Sciences. "Changing gut bacteria through diet affects brain function."ScienceDaily, 28 May 2013. Web. 29 May 2013.

3. Bakhtiar, SM, JG LeBlanc, E Salvucci, A Ali, R Martin, P Langella, JM Chatel, A Miyoshi, LG Bermúdez-Humarán, and V Azevedo. "Implications of the Human Microbiome in Inflammatory Bowel Diseases." Fems Microbiology Letters. 342.1 (2013): 10-7. Print.

4. Malago, Joshua J, Jos F. J. G. Koninkx, and Romana Marinšek-Logar. Probiotic Bacteria and Enteric Infections: Cytoprotection by Probiotic Bacteria. Dordrecht: Springer, 2011. Internet resource.

5. Diamond, B, PT Huerta, K Tracey, and BT Volpe. "It Takes Guts to Grow a Brain: Increasing Evidence of the Important Role of the Intestinal Microflora in Neuro and Immune-Modulatory Functions During Development and Adulthood." Bioessays : News and Reviews in Molecular, Cellular and Developmental Biology. 33.8 (2011): 588-91. Print.

6. Kollias, Helen. "Precision Nutrition » Research Review: Say hello to (my trillions of) little friends." Precision Nutrition . N.p., n.d. Web. 12 June 2013. <http://www.precisionnutrition.com/research-review-gut-bacteria>.

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Restoring Our Reefscape

© Richard Chesher

Ecosystem services are services produced through nature that directly and indirectly benefit humanity and support the entire Earth, such as purifying water, cycling nutrients, pollinating plants, or sequestering carbon. The importance of coral reefs cannot be understated; in terms of ecosystem services they provide habitat for an estimated 25-40% of discovered marine organism biodiversity (many of which are captured by us), aid in the protection of beach erosion, and - most importantly to many - serve as an excellent source of recreation. It should be mentioned that coral ecosystem’s biodiversity is unequaled in its genetic diversity also, providing key components of potential lifesaving compounds, such as those that fight some of the “worst infectious bacterial strains”, according to the National Oceanic and Atmospheric Administration.

But the coral reefs are at a greater risk of loss now than they have ever been in recorded history. A large amount of this blame rests on the shoulders of humanity in what has been informally termed the “Anthropocene” epoch by geologists and environmentalists. Increased ocean temperatures, mainly from increased greenhouse gas emissions by humans, and overfishing are two detrimental human-caused factors.

Readings of the carbon dioxide levels from May 2nd-7th, 2013 from the
Scripps Institution of Oceanography at the Mauna Loa Observatory.

Greenhouse gas changes caused by humans includes the majorly increased levels of carbon dioxide, stemming mainly from burning fuels based on carbon, like natural gas, oil, coal and wood. The increased carbon dioxide in the atmosphere cannot all be taken up in the usual chain of events, including photosynthesis that converts CO2 into organic carbon. The excess carbon dioxide is absorbed by the ocean, interacting with the seawater to create carbonic acid, which in turn decreases pH and affects the resident organisms. On May 7^th of this year, the carbon dioxide levels of the Mauna Loa Observatory reached 400 ppm – frightening, considering that the last time carbon dioxide levels were this high was nearly 2.5 million years ago and far higher than the pre-industrial 280 ppm.

In this symbiotic relationship, coral

provides carbon dioxide and water

for the algae's photosynthesis. The 

zooxanthallae releases oxygen, fats, 

and sugars - necessary for coral 

survival. 

© NOAA Ocean Service Education

The increase in acidity and temperature of the ocean is detrimental to coral reefs. Why? Because of the reefs symbiotic relationship with the algae known as zooxanthallae. When at healthy oceanic levels, the algae provide the coral polyps with oxygen, fats and sugars, which the coral then utilize for cellular respiration. The algae also provide the coral with its trademark bright colors. Cellular respiration creates CO2 and water, which the algae use for photosynthesis. To simplify this relationship, take a look at the animation on the right:

When coral polyps come under the stress of decreased pH and increased temperature, they may expel the zooxanthallae from their cells. This leads to the coral bleaching, the tell-tale sign of the algal expulsion. When coral bleaching occurs, the coral is weakened and therefore more susceptible to diseases and bacterial or viral infections [1]. Australian researchers have found an incredible way to measure the stress of corals. Recently, these researchers released a paper in Ecology and Evolution, discussing that hemoglobin protein gene has been found in the microalgae living with the coral that may be able to measure physiological stress, determining that “[hemoglobin] patterns can be affected by a number of factors including hypoxia, organogenesis, pathogen infection and ontogenesis” [2].

This could be potentially useful for conservation efforts and even industries to gauge the stress levels of the coral and their algal partners (and perhaps someday be able to intercept the seemingly doomed corals before bleaching occurs). Professor Hoegh-Guldberg of the ARC Centre of Excellence for Coral Reef Studies (CoECRS), describes the use of hemoglobin as a “potential… biomarker” capable of supplying “a clear readout of stress levels in the corals and their symbiotic algae”.

When first discovered, scientists believed that there was only one species of algal symbiont for all species of corals. That idea has been dispelled with the discovery of multiple groups of zooxanthallae, with a variety of different features and habitat preferences – including higher ocean temperatures thresholds. Dr. Andrew Baker of University of Miami, seen in the video below, and his associates are looking into this variation to find a way to prevent the coral from expelling the zooxanthallae in higher temperatures [3]. In laboratory tests, they have been artificially bleaching coral and then exposing it to ‘Clade D’ – a thermal resistant zooxanthallae variation – in an attempt to swap out the original symbiont for one that could survive in increased temperatures. In theory, this could be utilized in coral reefs that are beginning to experience increased ocean temperatures or to coral larvae that are artificially inserted in restoration areas.

Could you imagine if future conservationist could one day be able to monitor the stress levels of at-risk coral reefs (via the hemoglobin biomarkers mentioned previously) and introduce thermal resistant zooxanthallae in time to save them?

Climate change caused by human interaction is of huge importance to the destruction of coral habitats, but it is not the only cause of the “Anthropocene”. Overfishing of the coral itself and its inhabitants for consumption and decorum haunt the once flourishing reefs. Trawling of the ocean floor wipes out entire reef habitats, as does dynamite and cyanide fishing.

How do we raise concern for the preservation of Earth’s coral reefs?

TED Fellow and socio-ecological artist Colleen Flanigan has teamed up with the Global Coral Reef Alliance (GCRA) to fuse art, technology and conservation together to help raise awareness and promote the salvation of coral and its inhabitants. Since 2004, she has worked with GCRA and Biorock® using her background in design, gardening, and metalworking to “bring visibility to the problem”. Her main emphasis being that people may be inspired once they are able to interact with the beauty of a sculpted “coral refuge”.

Coral Skirt Biorock® sculpture transplanted to
reef in Bali. © colleenflanigan.com

Biorock® utilizes electrolysis to literally pull minerals necessary to calcify the shell of coral polyps to the metal framework, which once coral is transplanted to the metal frame increases growth rapidly. In her TEDtalk Coral Restoration: Cultivating Mutual Symbiosis, she enters the TEDx stage in Monterey, California in a costume resembling a mix between a jellyfish and a coral reef. Just great (see image below).

Getting ready to go onstage for her TEDx
Talk in Monterey, CA. © TED.

This implementation of beauty in the conservation of coral reefs may be the key to unlocking universal compassion and bring about more aggressive efforts to maintain coral reefs, which as mentioned earlier are extremely important for marine biodiversity, protection against erosion, and human recreation.

To learn more about the efforts of Colleen and the GCRA off of the coast of Mexico, visit their website. Want to learn how to get involved? Take a look at the U.S. Department of Commerce's National Oceanic & Atmosphere Administration's website, or opt to volunteer in the Florida Keys with expert divers through the Coral Restoration Foundation to transplant coral buds. Not looking to get that involved? Check out the Nature Conservancy's 10 easy ways to help preserve the reefs.


Citations:

Peer-Reviewed Articles:

1. [1] Jones, R., Bower, J., Hoegh-Guldberg, O. & Blackall, L., 2004. Dynamics of a temperature-related coral disease outbreak. Marine Ecology Progress Series 281, 63-77. 
2. [2] Baker, A., Glynn, P. & Riegl, B., 2008. Climate change and coral reef bleaching: An ecological assessment of long-term impacts, recovery trends and future outlook. Estuar. Coast. Shelf Sci., 1-37. 
3. [3] Baker, A. 2003. Flexibility and specificity in coral-algal symbiosis: Diversity, ecology, and biogeography of Symbiodinium, The Annual Review of Ecology, Evolution, and Systematics Online, 34, 661-689.

Media:

1. NOAA, “Coral as Medicine”. NOAA Coral Conservation Program: http://coralreef.noaa.gov/aboutcorals/values/medicine/
2. Walker, R. “Holy Holocene, It’s the Anthropocene”. Huffington Post: http://www.huffingtonpost.com/robert-walker/its-the-anthropocene_b_3149135.html
3. Biello, D. “400 PPM: Carbon Dioxide in the Atmosphere Reaches Prehistoric Levels”. Scientific American Blog: http://blogs.scientificamerican.com/observations/2013/05/09/400-ppm-carbon-dioxide-in-the-atmosphere-reaches-prehistoric-levels/
4. ARC Centre of Excellence. “‘Blood Test’ for Crook Corals”. ARC Centre of Excellence Coral Reef Studies: http://www.coralcoe.org.au/news/blood-test-for-crook-corals
5. The PEW Charitable Trust. “Helping Corals to Survive Climate Change and Warming Oceans” Research Program Project Details of Marine Fellow Andrew Baker: http://www.pewenvironment.org/research-programs/marine-fellow/id/8589941790/project-details
6. TED Fellows Profiles. “Colleen Flanigan”. TED: http://fellows.ted.com/profiles/colleen-flanigan
7. NOAA, “Get Involved”. NOAA Coral Conservation Program: http://coralreef.noaa.gov/getinvolved/
8. Coral Restoration Foundation, “Get Involved”. Coral Restoration Foundation: http://www.coralrestoration.org/get-involved/
9. The Nature Conservancy, “10 East Steps to Help Protect Coral Reefs”. The Nature Conservancy: http://www.nature.org/ourinitiatives/urgentissues/coralreefs/ways-to-help-coral-reefs/index.htm

Videos:

1. "Coral Restoration: Cultivating Mutual Symbiosis". Colleen Flanigan TEDx Monterey: http://www.youtube.com/watch?v=mj0Ymr2DzUY
2. "Heat Resistant Zooxanthellae". Dr. Andrew Baker with Reef Resilience: http://www.youtube.com/watch?v=Z6Qq0KyNmlo

For our own sake, foster urban biodiversity

Urban biodiversity is often overlooked in our general concept of conservation efforts. We picture national parks or other large swaths of protected land where wildlife is maintained separate from human populations.  However, research suggests that biodiversity conservation efforts in cities may be equally, if not more important than in remote parks. Ricketts and Imhoff (2003) performed a study in order to prioritize terrestrial ecoregions for conservation based on areas with high levels of both biodiversity and human threat. They created indices for species richness and endemism and defined human threat by land use. In addition to identifying priority locations, they found that conservation efforts may be more critical in human population centers (Ricketts and Imhoff, 2003).

                                         Credit: The Guardian

Biodiversity is important to cities beyond its contribution to overall conservation efforts. Green spaces in cities serve as critical migratory corridors for some species. People want access to nature and the services that come with it (Maddox, 2012). A 10% increase in urban tree canopy cover can result in 3-4 degree Celsius decrease in ambient temperature, reducing the need for air conditioning. However, one of the most compelling arguments for urban biodiversity is the health benefits. Rich diversity in cities contribute to ecosystem services such as improved air quality, dust filtering, and acting as a carbon sink. Proximity to plant life can reduce prevalence of childhood asthma and allergies (Simonsen, 2012). These are just a few examples of the myriad health benefits that biodiversity provides, but the bulk of investment in biodiversity conservation efforts currently focuses on land that is far away from population centers. However, given the health implications as more people move into in cities, a greater effort should be put toward studying and protecting urban biodiversity. Change can come through developing better protection schemes and incorporating considerations for biodiversity into urban design (Maddox, 2012), as well as community based efforts.

One mechanism for increasing urban biodiversity is to support urban agriculture efforts. Some cities already utilize urban farming a great deal; a 1996 UN report estimated that up to 80% of families in some Asian cities and others around the world are involved in agriculture. Urban agriculture itself has huge public health implications. Gardens can strengthen local food security when paired with support in the form of knowledge, tools and space. Though many variables affect agricultural outputs, given average growing conditions, a 10 by 10 meter plot can provide a household’s yearly vegetable needs including much of the nutritional requirements for vitamins A, C, B complex and iron (Brown and Jameton, 2000). While such a plot may not be a viable option for many city dwellers, smaller plots or community gardens can still contribute to increased nutrition. Gardens also contribute to improved personal wellness. Research supports the associated benefits of physical exercise, stress release, and other psychological and social benefits (Brown and Jameton, 2000). In fact, naturally occurring soil bacteria can act directly as a mood enhancer. One bacterium, mycobacterium vaccae, boosts serotonin levels and reduces anxiety (Healthy Organic).

                                         Credit: Inspiration Green

Urban agriculture improves public health through other forms of stress reduction as well. Community gardens help improve the social capital of neighborhoods. Indirect effects include reduced burglaries, thefts, and illicit drug dealing in neighborhoods with garden projects (Brown and Jameton, 2000). In addition to broadening our concept of biodiversity conservation, we must broaden our definition of the traditional concept of health. Though these community improvements don’t fall under traditional notions of health improvement, they have impacts on personal well-being.

Positive health benefits from increased urban biodiversity stem from a plethora of activities that are not limited to gardening. The state of Kerala in India just piloted a new Urban Biodiversity Enhancement Programme. Several polluted urban ponds have been turned over to residents’ associations for cleaning and restoration. Local residents transform these into urban biodiversity centers by planting medicinal plants and trees, some of which are native. One pond already has about 160 species of medicinal and flowering plants. Though the pilot ponds are in various stages of completion, the project is being considered a success and more ponds will soon be turned over (Unni, 2013). As well as improving the environmental and social health of the neighborhood, these projects provide a local source of plants with medicinal properties.

                             Restoration is almost complete at Mangannoorkonam pond, Pattom

                                         Credit: The New India Express

Urban agriculture can result in some negative environmental health consequences. These come from the use of chemical fertilizers and pesticides, which can cause negative health effects through direct exposure and pollution. Current and historically industrial sites have also been shown to cause health problems for those ingesting the food grown there. Plants take up hazardous manufacturing residues that can be toxic to humans in certain concentrations. On the other hand, phytoremediation (using plants to remove contaminants more efficiently) presents a potential solution to that issue, as well as improving the health of city land in general (Brown and Jameton, 2000).

There’s a caveat, however, for plant based biodiversity programs. A study of changing biodiversity patterns in cities found that plant species richness increases because of importation, but animal species richness tends to decline. This is because humans directly control plants but almost never animals and microbes—the implication being that conserving natural habitats defined by plants doesn’t guarantee the other components of biological community (Faeth et al., 2011). The fauna and microbes in a community are crucial for biodiversity and the ecosystem services they provide. This should be accounted for more in urban biodiversity efforts.

So how can more efforts be initiated? If biodiversity programs are going to occur in and be maintained by local communities or neighborhoods, an easy answer would be educating those residents about the importance of urban biodiversity. A study by Shwartz et al (2012) came about from the lack of existing evaluation of the effectiveness of urban conservation programs that are meant to increase action toward and knowledge of biodiversity. Their study examined the influence of an urban conservation activity day on knowledge, awareness and actions toward biodiversity in Paris. They founds that a single activity day increased interest and knowledge of local urban biodiversity but had little effect in the long term. Subsequently, they hypothesize that repeated education programs could achieve conservation goals more effectively (Shwartz et al., 2012). This comes as no surprise; real effort toward biodiversity conservation requires a sustained commitment. However, the benefits of such work are undeniable, from as big a scale as global biodiversity conservation down to the health of each urban individual.

                                         Credit: Notice Nature

Works Cited

Brown, Kate H., and Andrew Jameton. "Public Health Implications of Urban Agriculture." Journal of

                Public Health Policy 21.1 (2000): 20-39. 

Faeth, Stanley H., Christofer Bang, and Susanna Saari. "Urban Biodiversity: Patterns and

                Mechanisms." Annals of the New York Academy of Sciences (2011): 69-81.

Healthy Organic. "Soil Bacteria Makes You Happy." Web. <http://healthyorganic.co.za/soil-bacteria-

makes-you-happy/>.

Maddox, David. "Shift Investment to Urban Biodiversity." Sound Science Blog. 9 Feb. 2012. Web.

<http://sound-science.org/blog/2012/02/09/shift-investment-to-urban-biodiversity/>.

Ricketts, Taylor, and Marc Imhoff. "Biodiversity, Urban Areas, and Agriculture: Locating Priority

Ecoregions for Conservation." Conservation Ecology 8.2 (2003).

Shwartz, Assaf, Alix Cosquer, Alexandre Jaillon, Armony Piron, Romain Julliard, Richard Raymond,

Laurent Simon, and Anne-Caroline Prévot-Julliard. "Urban Biodiversity, City-Dwellers and Conservation: How Does an Outdoor Activity Day Affect the Human-Nature Relationship?" PLoS ONE 7.6 (2012).

Simonsen, Sturle. "Rich Biodiversiy Can Curb Urban Health Issues - Stockholm Resilience Centre." Rich

Biodiversiy Can Curb Urban Health Issues - Stockholm Resilience Centre. 15 Oct. 2012. Web. <http://www.stockholmresilience.org/21/research/research-news/10-15-2012-rich-biodiversiy-can-curb-urban-health-issues.html>.

Unni, Aparna. "Urban Pond Rejuvenation Tastes Success." The New Indian Express. 23 May 2013.

Web. <http://newindianexpress.com/cities/thiruvananthapuram/Urban-pond-rejuvenation-tastes-success/2013/05/23/article1602009.ece>.

Soil Health: The Realtionbship Between Soil, Bacteria, and Plants

 

The soil has diverse communities of organisms, as well as complex biological functions, which enable plants and crops to grow. In addition, people use pesticides in order to get rid of pests that can harm the plants’ health. Its use influences the microbes around it, and has consequences for the soil. Herbicides, pesticides, as well as other chemicals and pollutants, can disrupt biological functions in the soil, and can even reduce the amount of CO2 in it (Mishra 2004). Even worse, if these accumulate in the soil, it degrades it at a later point. Currently, scientists believe that using bacteria and nutrients can help plants and soil against damage by chemical pollutants, which would enable plants and crops to keep growing healthy.

According to Upasan Mishra and Dolly Wattal Dhar’s paper, “Biodiversity and Biological Degradation of Soil”, pesticides can reduce the amount of CO2 production, degrade cellulose, and can inhibit biological function in the soil. For example, at normal doses, amitrole, 2,4-DB, and diallate can inhibit nitrification for about eight weeks (Mishra 2004). This is a longer inhibition period than atrazine, bromacil, picloram, and simzine, but that doesn’t mean that these four pollutants are nay better. Damage to the soil can also inhibit the plant from absorbing nutrients available in the soil, if they have not died already. Repairing the damage done to it would take a long time, but even if this were accomplished, the soil would never return to its original and pristine state. 

 

A study from 2012 shows that even dead bacteria is important for the soil because its converted into soil components. It was commonly assumed that organic components in the soil were made from decomposed plants, but the truth is that degraded plant material is initially convereted into microbial biomass, that then provides source for soil organic matter (Arnhold 2012). This is imortant because part of the reason why CO2 escapes unto the atmostphere is because of the degraded organic material in soils. This will affect climate, which will also have an effect on soil fertility. This fact emphasises the imporatnce of keeping soil healthy. To prevent this from happening, its important to ensure that soil is healthy enough for plants and crops to grow in. Since long term effects from soil pollutants inhibit biological processess, and has the potential to damage soil, we must look at other alternatives to keep soil fertile and healthy, even if its no longer in its pure state. However, to accomplish this, soil’s relationship with plants, bacteria, and nutrients needs to be understood.

Strategies for repairing damaged soil, and to grow healthy plants, all have one thing in common; the relationship between plants and the soil. This relationship is basically the plants interacting with the soil whether it’s the plant absorbing nutrients from the soil, or building immunity against bad bacteria in soil. In Amy Coombs’ article, “Fighting Microbes with Microbes”, an experiment with tomato plants is used to explain a mechanism of the relationship in action. During the experiment, tomato plants were covered with plastic bags for a time; part of the tomato plants, inoculated with the Alternaria solani fungus, had their fruit rot. Meanwhile, the rest, that were not inoculated, were able to build a defense against the fungus, and made enzymes that would fight against the fungus. Why?

An interaction between the soil and a different fungus was found to a possible cause; the Glomus Mosseae, which attaches itself to the plant’s root hair, forming a symbiotic relationship with the plant. In other words, this warns the plant, through the roots, to create defenses against Alternaria solani. Researchers are certain that, based on this discovery, “the mycorrhizal network can extend from one set of plant roots to another, it’s possible that the network of fungal mycelia acts like telephone wires, allowing the plants to communicate underground” (Coombs, 2013). However, this is currently just a hypothesis; not much is known to researchers about the specific details of this mechanism, so how this relationship works is not completely understood yet. If this hypothetical communication were understood and proven to be correct, then scientists would use this as a way to prevent disease in plants by cultivating a mix of good microbes into the soil to accomplish this goal. The benefit from this would be that the amount of pesticides, and other chemical products generally used in soil, would be reduced. This in turn would reduce, or prevent, further damage to the soil by pollutants.

A research paper by Richardson et al, “Plant and Microbial Strategies to Improve Phosphorous Efficiency of Agriculture”, suggest a different alternative. It outlines three possible strategies where  plants and microorganisms could possibly improve phosphorous efficiency “(i) Root-foraging strategies that improve P acquisition by lowering the critical P requirement of plant growth and allowing agriculture to operate at lower levels of soil P; (ii) P-mining strategies to enhance the desorption, solubilisation or mineralisation of P from sparingly-available sources in soil using root exudates (organic anions, phosphatases), and (iii) improving internal P-utilisation efficiency through the use of plants that yield more per unit of P uptake” (Richardson et al 2011). The Richardson team believes that P-efficient plants can be created if “architecture” and root growth is modified, through root manipulation or by managing mycorrhizal fungi and microbial inoculants.

However, the success from the genetically manipulated plants to enhance nutrient secretion from roots, is very difficult to repeat outside controlled lab procedures due to variable results given after being evaluated in soil. The team concludes that understanding “trait interactions and the ecophysiology of the rhizosphere is emerging as an important factor in development of improved plants via these P-efficiency routes”, because it’s important to consider this when trying to breed plants for P-efficieny (Richardson et al). According to the article, these novel P-efficiency plants (with better root traits and extracting genotypes) can be beneficial in an agro-ecological and socio-economic system level, as it can lessen P-depletion.

In another study, the “Using soil bacteria to facilitate phytoremediation” paper by Bernard R. Glick, explored the possibility of using soil bacteria with plants to remove pollutants from the soil. Here, pythoremoderation (where plants are used to remove pollutants from soils and water) would be assisted by soil bacteria to work against organic and metallic contaminants. Glick hopes that not only could phytoremediation be facilitated, but future field research studies as well when dealing with toxic contaminants and pollutants (Glick 2010).

Unfortunately, there were complexities during the experiment that made it difficult to create an ideal set of conditions that can work for all phytoremediation experiments. These ranged from plant type, added bacteria, and soil composition, to conditions of contaminants found in soil and temperature range. There was also a drawback; while the method was used against metallic and organic pollutants inside controlled laboratory conditions, it has not been tried for metallic pollutants outside of them (Glick 2010). This is worrisome, because metallic pollutants are far more harmful to the soil than organic ones. Another unfortunate bit; some of the plants could not produce enough biomass inside these controlled conditions to be considered efficient in the field. Glick concludes that; 1.) “obstacles” in the experiment are traceable, 2.) it is important to address problems of metal bioavailability in contaminated soils, and 3.) to use phytoremediation, assisted by bacteria, on a larger scaled environment of organic and/or metal pollutants. All which will require a better understanding of the relationship between, soils, plants, contaminants, and bacteria with each other, as well as with phytoremediation assisted by bacteria.

Scientist researching these alternative methods to improve soil health look very promising, but unfortunately for them to be successful, and for the use in chemicals to be reduced, soil’s relationship with plants needs to be understood. This is because it will be beneficial in the long run, both health wise and economically.

Sources:

Arnhold, Tilo. "Fertile soil doesn't fall from the sky. The contribution of bacterial remnants to soil fertility has been underestimated until now." Research for Environment. Hermholtz Centre for Environmental Research-UFZ, 14 Dec 2012. Web. 29 May 2013. <http://www.ufz.de/index.php?en=31184>.

Coombs, Amy. "Fighting Microbes with Microbes." Scientist. 1 Jan 2013: n. page. Web. 29 May. 2013. <http://www.the-scientist.com/?articles.view/articleNo/33703/title/Fighting-Microbes-with-Microbes/>.

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