# Gut Fungal Community Modulates Fat Deposition in Ningxiang Pigs: Species-Specific Regulation via the Glucose–SCFAs Metabolic Axis

## TL;DR

This study shows that gut fungi in Chinese pigs influence fat levels by affecting glucose and short-chain fatty acids, offering new strategies for pig breeding.

## Contribution

The paper identifies a fungal-driven 'Glucose–SCFAs axis' as a novel mechanism for fat regulation in pigs.

## Key findings

- NX pigs had higher fat and glucose but lower SCFAs compared to DLY pigs.
- Aspergillus and Penicillium in NX pigs correlated with glucose and reduced SCFAs.
- Rhodotorula in DLY pigs was linked to higher SCFAs and lipolysis.

## Abstract

This study reveals a gut fungal-mediated mechanism regulating fat deposition in indigenous Chinese pigs. Compared to lean-type Duroc × Landrace × Yorkshire (DLY) pigs, high-fat Ningxiang (NX) pigs showed significantly higher fat deposition and serum glucose, but markedly lower colonic short-chain fatty acids (SCFAs). Distinct fungal communities were observed: NX pigs enriched with Aspergillus and Penicillium positively correlated with glucose but negatively with SCFAs, while DLY pigs’ dominant Rhodotorula strongly correlated with SCFAs. Metabolic analysis linked NX-enriched fungi to enhanced polysaccharide degradation and glucose bioavailability. We propose a fungal-driven “Glucose–SCFAs axis”: NX-associated fungi elevate glucose while suppressing SCFAs. Conversely, Rhodotorula in DLY enhances SCFA-induced lipolysis.

Despite limited understanding of gut fungal roles in fat deposition among indigenous pig breeds, a comparative study between high-fat-accumulating Ningxiang (NX) pigs and lean-type Duroc × Landrace × Yorkshire (DLY) pigs reveals a fungal-driven regulatory mechanism. NX pigs exhibited significantly higher fat percentage, elevated serum glucose, and markedly reduced total colonic short-chain fatty acids (SCFAs) compared to DLY pigs (all p < 0.001), with butyrate showing the most pronounced decrease. Beta-diversity confirmed distinct fungal communities (p = 0.002), where NX pigs were enriched with Aspergillus and Penicillium, while DLY pigs harbored dominant Rhodotorula. Strong correlations were observed: NX-enriched fungi positively correlated with glucose and negatively with SCFAs, whereas Rhodotorula strongly associated with SCFAs (p < 0.001). FUNGuild analysis linked Aspergillus/Penicillium to enhanced polysaccharide degradation and glucose bioavailability. The findings propose a gut fungal-mediated “Glucose–SCFAs axis”: NX-enriched fungi elevate glucose (promoting lipogenesis) and suppress SCFAs (reducing butyrate-mediated adipocyte inhibition), whereas Rhodotorula in DLY pigs enhances SCFAs-induced lipolysis. Crucially, we demonstrate that fungal modulation primarily drives fat deposition differences between breeds, offering novel probiotics/antifungal strategies for precision swine breeding.