Study creates bacteria that consume carbon dioxide for growth

Agencies
November 30, 2019

Washington D.C., Nov 30: Researchers have developed bacteria called Escherichia coli, which consume carbon-di-oxide for energy instead of organic compounds.

This creation in synthetic biology highlights the incredible plasticity of bacterial metabolism and could provide the framework for future carbon-neutral bioproduction. The work appeared in the journal -- Cell.

"Our main aim was to create a convenient scientific platform that could enhance CO2 fixation, which can help address challenges related to the sustainable production of food and fuels and global warming caused by CO2 emissions," said senior author Ron Milo, at systems biologist at the Weizmann Institute of Science.

"Converting the carbon source of E. coli, the workhorse of biotechnology, from organic carbon into CO2 is a major step towards establishing such a platform," added Milo.

A grand challenge in synthetic biology has been to generate synthetic autotrophy within a model heterotrophic organism.

Despite widespread interest in renewable energy storage and more sustainable food production, past efforts to engineer industrially relevant heterotrophic model organisms to use CO2 as the sole carbon source has failed.

Previous attempts to establish autocatalytic CO2 fixation cycles in model heterotrophs always required the addition of multi-carbon organic compounds to achieve stable growth.

"From a basic scientific perspective, we wanted to see if such a major transformation in the diet of bacteria -- from dependence on sugar to the synthesis of all their biomass from CO2 -- is possible," said first author Shmuel Gleizer (@GleizerShmuel), a Weizmann Institute of Science postdoctoral fellow.

"Beyond testing the feasibility of such a transformation in the lab, we wanted to know how extreme an adaptation is needed in terms of the changes to the bacterial DNA blueprint," added Gleizer.

The researchers used metabolic rewiring and lab evolution to convert E. coli into autotrophs. The engineered strain harvests energy from formate, which can be produced electrochemically from renewable sources.

Because formate is an organic one-carbon compound that does not serve as a carbon source for E. coli growth, it does not support heterotrophic pathways.

They inactivated central enzymes involved in heterotrophic growth, rendering the bacteria more dependent on autotrophic pathways for growth.

They also grew the cells in chemostats with a limited supply of the sugar xylose -- a source of organic carbon -- to inhibit heterotrophic pathways.

The initial supply of xylose for approximately 300 days was necessary to support enough cell proliferation to kick start evolution. The chemostat also contained plenty of formates and a 10% CO2 atmosphere.

By sequencing the genome and plasmids of the evolved autotrophic cells, the researchers discovered that as few as 11 mutations were acquired through the evolutionary process in the chemostat.
One set of mutations affected genes encoding enzymes linked to the carbon fixation cycle.

The authors said that one major study limitation is that the consumption of formate by bacteria releases more CO2 than is consumed through carbon fixation.

In addition, more research is needed before it's possible to discuss the scalability of the approach for industrial use.

In future work, the researchers will aim to supply energy through renewable electricity to address the problem of CO2 release, determine whether ambient atmospheric conditions could support autotrophy, and try to narrow down the most relevant mutations for autotrophic growth.

"This feat is a powerful proof of concept that opens up a new exciting prospect of using engineered bacteria to transform products we regard as waste into fuel, food or other compounds of interest," Milo said.

"It can also serve as a platform to better understand and improve the molecular machines that are the basis of food production for humanity and thus help in the future to increase yields in agriculture," added Milo.

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Agencies
May 30,2020

Drinking coffee may help reduce the risk of certain digestive disorders, including gallstone disease and pancreatitis, a new study has suggested.

The study from the Institute for Scientific Information on Coffee (ISIC) also highlighted other beneficial effects that coffee consumption may have on the process of digestion, including supporting gut microflora and promoting gut motility.

"Data indicates benefits against common digestive complaints such as constipation, as well as a potential reduction in the risk of more serious conditions like chronic liver diseases," said study author Carlo La Vecchia from the University of Milan in Italy.

Gallstone disease is a common digestive disorder, caused by the accumulation of gallstones in the gallbladder or bile duct, which affects approximately 10-15 per cent of the adult population.

While the mechanism by which coffee may protect against gallstone disease is not yet known, it has been observed that the risk for the condition declines with increasing daily consumption of coffee, the researchers said.

Caffeine is thought to play a role in these associations, as the same effect is not observed with decaffeinated coffee.

A common question among consumers and focus area for research is whether coffee is associated with heartburn or gastro-oesophageal reflux disease (GORD).

While a small number of studies have suggested an association between coffee drinking and GORD, the majority of studies reviewed suggest that coffee is not a major trigger of these conditions.

The report also reviewed a growing area of health and nutrition research, namely: the effect of coffee on the gut microflora (microorganism populations).

Recent studies suggest that populations of the beneficial gut bacteria Bifidobacterium spp, increase after drinking coffee.

The findings showed the dietary fibre and polyphenols found in coffee, support the healthy growth of microflora populations.

Additional research findings highlighted that coffee consumption is thought to stimulate digestion by encouraging the release of gastric acid, bile and pancreatic secretions.

Coffee is one of the most widely researched components of the diet, and its effect on digestion remains a growing area of research, the researchers noted.

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Agencies
July 8,2020

Probiotics that broaden the mix of helpful bacteria in the gut may help to ease depression, say researchers.

Foods that broaden the profile of helpful bacteria in the gut are collectively known as probiotics. These "good bacteria" can be taken as supplements, or found naturally in yoghurts or fermented foods.

For the findings, the research team from the University of Brighton in the UK searched for relevant studies published in English between 2003 and 2019, which looked at the potential therapeutic contribution of pre-and probiotics in adults with depression and/or anxiety disorders.

Out of an initial haul of 71 studies, just seven met all the criteria for inclusion. All 7 investigated at least one probiotic strain; four looked at the effect of combinations of multiple strains.In all, 12 probiotic strains featured in the selected studies, primarily Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidium.

One study looked at combined pre-probiotic treatment, while one looked at prebiotic therapy by itself. The studies varied considerably in their design, methods used, and clinical considerations, but all of them concluded that probiotic supplements either alone or in combination with prebiotics may be linked to measurable reductions in depression.

And every study showed a significant fall or improvement in anxiety symptoms and clinically relevant changes in biochemical measures of anxiety or depression with probiotic or combined pre-probiotic use.

Of the 12 different probiotics investigated, 11 were potentially useful, the findings showed.'Probiotics may help reduce the production of inflammatory chemicals, such as cytokines, as is the case in inflammatory bowel disease, the researchers suggested.

"They may help direct the action of tryptophan, a chemical thought to be important in the gut-brain axis in psychiatric disorders," they added.

In this way, with a better understanding of the mechanisms, probiotics may prove to be a useful tool across a wide range of conditions," the authors wrote.

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Agencies
February 20,2020

The health and future of every child and adolescent worldwide is under immediate threat from ecological degradation, climate change and exploitative marketing practices that push fast food, sugary drinks, alcohol and tobacco at children, said a new report on Wednesday.

No single country is adequately protecting children's health, their environment and their futures, according to the report by a commission of over 40 child and adolescent health experts from around the world.

The commission, convened by the World Health Organization (WHO), the United Nations children's agency, Unicef, and medical journal the Lancet, found that while the poorest countries need to do more to support their children's ability to live healthy lives, excessive carbon emissions --disproportionately from wealthier countries -- threaten the future of all children.

"Despite improvements in child and adolescent health over the past 20 years, progress has stalled, and is set to reverse," said former Prime Minister of New Zealand and Co-Chair of the Commission, Helen Clark.

"It has been estimated that around 250 million children under five years old in low- and middle-income countries are at risk of not reaching their developmental potential, based on proxy measures of stunting and poverty. But of even greater concern, every child worldwide now faces existential threats from climate change and commercial pressures," Clark said.

The report, titled "A Future for the World's Children?", includes a new global index of 180 countries, comparing performance on child flourishing and sustainability, with a proxy for greenhouse gas emissions, and equity, or income gaps.

India ranked 131 among the 180 countries in the index.

The index shows that children in Norway, the Republic of Korea, and the Netherlands have the best chance at survival and well-being, while children in the Central African Republic, Chad, Somalia, Niger and Mali face the worst odds.

However, when the authors took per capita CO2 emissions into account, the top countries trail behind: Norway ranked 156, the Republic of Korea 166, and the Netherlands 160.

Each of the three emits 210 per cent more CO2 per capita than their 2030 target.

The US, Australia, and Saudi Arabia are among the ten worst emitters.

If global warming exceeds 4 degree Celsius by the year 2100 in line with current projections, this would lead to devastating health consequences for children, due to rising ocean levels, heatwaves, proliferation of diseases like malaria and dengue, and malnutrition, said the report.

The only countries on track to beat CO2 emission per capita targets by 2030, while also performing fairly (within the top 70) on child flourishing measures are: Albania, Armenia, Grenada, Jordan, Moldova, Sri Lanka, Tunisia, Uruguay and Vietnam.

The report also revealed the distinct threat posed to children from harmful marketing. Evidence suggests that children in some countries see as many as 30,000 advertisements on television alone in a single year, while youth exposure to vaping (e-cigarettes) advertisements increased by more than 250 per cent in the US over two years, reaching more than 24 million young people.

Children's exposure to commercial marketing of junk food and sugary beverages is associated with purchase of unhealthy foods and overweight and obesity, linking predatory marketing to the alarming rise in childhood obesity, said the report.

The number of obese children and adolescents increased from 11 million in 1975 to 124 million in 2016 - an 11-fold increase, with dire individual and societal costs.

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