(1) Background: Carbohydrates are the most important source of nutritional energy for the human body. Carbohydrate digestion, metabolism, and their role in the gut microbiota modulation are the focus of multiple studies. The objective of this weight of evidence systematic review is to investigate the potential relationship between ingested carbohydrates and the gut microbiota composition at different taxonomic levels. (2) Methods: Weight of evidence and information value techniques were used to evaluate the relationship between dietary carbohydrates and the relative abundance of different bacterial taxa in the gut microbiota. (3) Results: The obtained results show that the types of carbohydrates that have a high information value are: soluble fiber with Bacteroides increase, insoluble fiber with Bacteroides and Actinobacteria increase, and Firmicutes decrease. Oligosaccharides with Lactobacillus increase and Enterococcus decrease. Gelatinized starches with Prevotella increase. Starches and resistant starches with Blautia decrease and Firmicutes increase. (4) Conclusions: This work provides, for the first time, an integrative review of the subject by using statistical techniques that have not been previously employed in microbiota reviews.

In recent years, renewable sources of energy have been sought due to the environmental impacts associated with fossil fuels, such as greenhouse gas emissions into the atmosphere. A promising alternative is biodiesel, particularly when obtained using yeast, as they offer certain advantages over other microorganisms due to their resilience to grow in various conditions, short reproduction times, and lower susceptibility to bacterial infections because they thrive at lower pH levels and have the ability to utilize a wide variety of substrates. Furthermore, biodiesel produced with yeast is composed of methyl ester fatty acids (FAME), providing it with good quality and performance in internal combustion engines, resulting in reduced greenhouse gas emissions compared to conventional diesel. The production of biodiesel using yeast involves six general stages, which offer various methodological alternatives with different degrees of sustainability. The objective of this review is to assess the sustainability degree of various methodologies employed in each of the stages of yeast-based biodiesel production through environmental and economic sustainability indicators.