Research Progresses on the Function and Detection Methods of Insect Gut Microbes

The insect gut is home to an extensive array of microbes that play a crucial role in the digestion and absorption of nutrients, as well as in the protection against pathogenic microorganisms. The variety of these gut microbes is impacted by factors such as age, diet, pesticides, antibiotics, sex, and caste. Increasing evidence indicates that disturbances in the gut microbiota can lead to compromised insect health, and that its diversity has a far-reaching impact on the host's health. In recent years, the use of molecular biology techniques to conduct rapid, qualitative, and quantitative research on the host intestinal microbial diversity has become a major focus, thanks to the advancement of metagenomics and bioinformatics technologies. This paper reviews the main functions, influencing factors, and detection methods of insect gut microbes, in order to provide a reference and theoretical basis for better research utilization of gut microbes and management of harmful insects.

Stool microbiota show greater linkages with plasma metabolites compared to salivary microbiota in a multinational cirrhosis cohort

BACKGROUND AND AIMS

Cirrhosis is associated with changes in gut microbiota in both saliva and stool. The relative linkage patterns of stool versus saliva microbiota with systemic metabolomics are unclear and may differ across countries. We hypothesized that stool microbiota have greater linkages with plasma metabolites than saliva microbiota, which may depend on country of origin.

METHODS

Age-balanced controls and outpatient patients with cirrhosis, compensated and decompensated, from the USA and Mexico (MX) underwent plasma collection and dietary recall. Plasma metabolomics were analysed using nuclear magnetic resonance spectroscopy. Microbiota in stool and saliva samples were analysed using 16S rRNA analyses. Correlation network differences between both saliva and stool gut microbiota and plasma metabolites were compared between subject groupings and within/between countries.

RESULTS

A total of 313 age-balanced subjects-135 USA (47 control, 48 compensated and 40 decompensated) and 178 MX (71 control, 56 compensated and 51 decompensated)-were enrolled. Cirrhosis severity, including lactulose and rifaximin use, were comparable. Plasma metabolites differed with advancing cirrhosis, between countries and according to 90-day hospitalizations. Correlation networks demonstrated more microbiome-metabolite linkages in stool compared to saliva in both populations, although there were no salivary correlation metrics across decompensated subjects in either country. Stool Lactobacillus showed a positive correlation to plasma lactate in decompensated cirrhosis from MX but not USA.

CONCLUSIONS

Stool microbiota were more extensively linked with systemic metabolites than were saliva microbiota, irrespective of cirrhosis severity and country. These changes were more prominent in decompensated cirrhosis and were centred around plasma lactate, which might reflect the interaction of diet and lactulose therapy.

Metabolomics and microbial composition increase insight into the impact of dietary differences in cirrhosis

BACKGROUND & AIMS

Dietary changes can modulate gut microbiota and interact with cirrhosis. Our prior study demonstrated that microbial diversity was higher in cirrhotics from Turkish vs the USA, which was associated with lower risk of 90-day hospitalizations. We aimed to define gut microbial functional and metabolomic changes to increase insight into benefits of the Mediterranean compared to Western diets.

METHODS

In all, 139 Turkish (46 controls/50 compensated/43 decompensated) and 157 American subjects (48 controls/59 compensated/50 decompensated) were studied. Turkish subjects consumed a modified Mediterranean diet with daily fermented milk intake, whereas Americans consumed a Western diet. Predicted gut microbial functionalities and plasma metabolomics were compared between/within countries. Correlation network differences between microbiota and metabolites in cirrhotics from Turkey vs the USA were evaluated.

RESULTS

Predicted microbial function showed lower amino acid, bioenergetics and lipid pathways, with functions related to vitamin B, glycan, xenobiotic metabolism, DNA/RNA synthesis, in cirrhotics from Turkey compared to the USA. Plasma metabolomics demonstrated higher relative lactate levels in Turkey vs the USA. The metabolite changes in decompensated cirrhosis, compared to controls, showed similar trends in Turkey and the USA, with reduced lipids and phosphocholines. Phosphocholines were significantly lower in patients hospitalized in 90 days (P = .03). Correlation networks in cirrhotics demonstrated linkage differences between beneficial taxa, Blautia and Oscillispira, and lactate and unsaturated lipids, in Turkey compared to American patients.

CONCLUSIONS

A modified Mediterranean diet was associated with altered plasma metabolomics and beneficially alters microbiota functionality and correlations compared to Western diet in cirrhosis. These altered diet-microbial interactions could potentially affect the 90-day hospitalization risk.