Associations between bacterial and fungal communities in the human gut microbiota and their implications for nutritional status and body weight

Abstract

This study examined the interplay between bacterial and fungal communities in the human gut microbiota, impacting on nutritional status and body weight. Cohorts of 10 participants of healthy weight, 10 overweight, and 10 obese individuals, underwent comprehensive analysis, including dietary, anthropometric, and biochemical evaluations. Microbial composition was studied via gene sequencing of 16S and ITS rDNA regions, revealing bacterial (bacteriota) and fungal (mycobiota) profiles. Bacterial diversity exceeded fungal diversity. Statistically significant differences in bacterial communities were found within healthy-weight, overweight, and obese groups. The Bacillota/Bacteroidota ratio (previously known as the Firmicutes/Bacteroidetes ratio) correlated positively with body mass index. The predominant fungal phyla were Ascomycota and Basidiomycota, with the genera Nakaseomyces, Kazachstania, Kluyveromyces, and Hanseniaspora, inversely correlating with weight gain; while Saccharomyces, Debaryomyces, and Pichia correlated positively with body mass index. Overweight and obese individuals who harbored a higher abundance of Akkermansia muciniphila, demonstrated a favorable lipid and glucose profiles in contrast to those with lower abundance. The overweight group had elevated Candida, positively linked to simple carbohydrate consumption. The study underscores the role of microbial taxa in body mass index and metabolic health. An imbalanced gut bacteriota/mycobiota may contribute to obesity/metabolic disorders, highlighting the significance of investigating both communities.

Keywords: Candida; Bacillota/Bacteroidota (Firmicutes/Bacteroidetes) ratio; Gut bacteriota; Gut dysbiosis; Gut mycobiota; Obesity.

Figure 1

Beta diversity analysis of the dataset focusing on the bacterial (a) and fungal (b) genera present in the gut microbiota of the participants.

Figure 2

Taxonomic assignments of the intestinal bacteriota (IBac) and intestinal mycobiota (IMy) of participants, presented at the phylum (a, c) and genus (b, d) levels, respectively, using the QIIME 2.0 software.

Figure 3

Volcano plots show statistically significant differences between weight groups in bacterial and fungal genus abundance. The x-axis shows the log2 of the fold change and the y-axis shows the -log of the p-value. (a) bacterial genera between the overweight and healthy-weight groups, (b) bacterial genera between the obese and healthy-weight groups, (c) bacterial genera between the obese and overweight groups, and (d) fungal genera between the obese and healthy-weight groups.

Figure 4

Comparison of the linear discriminant analysis of bacterial genera (a) and fungal genera (b) found in the intestinal microbiota of healthy-weight, overweight, and obese groups.

Figure 5

Spearman correlation analysis of intestinal bacterial genera among the healthy-weight, overweight, and obese groups with anthropometric (a), biochemical (b), and dietary (c) variables. Total iron-binding capacity (TIBC) high-density lipoprotein (HDL), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamic gamma transferase (GGT), and lactate dehydrogenase (LDH). *p < 0.05.

Figure 6

Spearman correlation analysis of intestinal fungal genera among the healthy-weight, overweight, and obese groups with anthropometric (a), biochemical (b), and dietary (c) variables. Total iron-binding capacity (TIBC) high-density lipoprotein (HDL), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamic gamma transferase (GGT), and lactate dehydrogenase (LDH). *p < 0.05.