Absence of stress-promoted facilitation coupled with a competition decrease in the microbiome of ephemeral saline...

Area of Science:

• Microbial ecology
• Environmental science
• Ecology

Background:

• Salinity fluctuations are major drivers of microbial distribution and abundance globally.
• The impact of increasing saline stress on microbial interactions remains poorly understood.
• Ephemeral saline lakes provide a unique model system to study these effects.

Purpose of the Study:

• To investigate how severe salinity fluctuations affect microbial interactions within aquatic microbiomes.
• To differentiate between environmentally driven associations and true biological interactions.
• To understand the role of competition and facilitation under increasing saline stress.

Main Methods:

• Utilized a probabilistic method to identify significant co-occurrences and co-exclusions in microbial networks.
• Employed a conceptual framework to filter out environmental and spatial influences on interactions.
• Conducted network analysis on bacteria, eukarya, and archaea across a salinity gradient in ephemeral lakes.

Main Results:

• Most observed microbial co-occurrences/exclusions were attributed to environmental niche or dispersal limitations.
• Microbial co-occurrences, potentially representing biological interactions, remained stable across the salinity gradient.
• Co-exclusions, indicative of competition, decreased in number and network complexity with increasing salinity.

Conclusions:

• Increasing saline stress in ephemeral lakes reduces microbial competition.
• Facilitation processes among microbes are not promoted by the studied salt gradient.
• Microbial community structure and interactions are significantly shaped by salinity, with competition decreasing under higher stress.