Persistent global greening over the last four decades using novel long-term vegetation index data with enhanced temporal consistency


                  

 Global warming is gradually becoming more serious, and its pace is accelerating. The terms "climate crisis" and "climate catastrophe" are now being used to describe the situation. The Earth's surface is kept warm by the absorption of solar radiation by greenhouse gases in the atmosphere, which trap heat. Global warming occurs when the concentration of these greenhouse gases increases excessively. The most direct way to mitigate global warming is to reduce the amount of greenhouse gases. In 2023, carbon dioxide accounted for 74% of global greenhouse gas emissions, followed by methane, which made up 17%. Although the total amount of methane emissions is smaller compared to carbon dioxide, methane has 25 times the greenhouse effect of carbon dioxide, making it a crucial factor in efforts to reduce greenhouse gas emissions.

 As the global population grows, the demand for meat consumption is also increasing. Methane is produced during the digestive process of ruminant animals. As a result, there is a growing policy and market demand to reduce methane emissions from cattle in the livestock industry. Methane in the rumen is produced through complex interactions between various microorganisms, which has led to research on various feed additives to inhibit methane production in the rumen. While many studies have been conducted on feed additives that suppress methane production, the complexity of the microbial environment in the rumen means that most additives have limited effectiveness, and there is a lack of research on their mechanisms of action. Therefore, it is necessary not only to find new methane-suppressing additives but also to clarify their mechanisms of action.

 In this study, we aimed to enhance methane reduction by using Escherichia coli probiotic strain Nissle 1917 (EcN) as a novel feed additive, combined with biochar, a substance known to increase microbial activity. Escherichia coli is advantageous because it is genetically manipulable, allowing for the strengthening or weakening of specific biological functions, which makes it possible to guide the desired role in the rumen microbial community. Biochar, a type of activated carbon, is made by pyrolyzing various biomass, which evaporates the organic matter and leaves only the inorganic components. Biochar has a porous structure and contains various inorganic elements depending on the type of biomass used in its production. In this study, we observed the changes when EcN and biochar were applied together to rumen fluid, using various analytical methods. Additionally, we confirmed the application mechanism of EcN in rumen fluid by removing key functions related to methane reduction using the CRISPR/Cas9 system and analyzing the resulting changes.