Functional Transcripts Indicate Phylogenetically Diverse Active Ammonia-Scavenging Microbiota in Sympatric Sponges

Area of Science:

• Marine microbiology
• Sponge biology
• Biogeochemical cycles

Background:

• Sponges host diverse microbial communities involved in nutrient cycling.
• Ammonia scavenging by symbiotic microbes is crucial for sponge health and ecosystem function.
• Limited understanding exists regarding the in situ activity and phylogenetic diversity of ammonia-scavenging microbiota in different sponge species.

Purpose of the Study:

• To investigate the phylogenetic diversity and in situ activity of ammonia-scavenging microbiota in sympatric sponges.
• To identify the key functional genes and microbial lineages involved in ammonia removal within sponges.
• To compare the ammonia-scavenging microbial communities across different sponge species and seawater.

Main Methods:

• Analysis of transcribed ammonia monooxygenase (amoA), hydrazine synthase (hzsA), and glutamine synthetase (glnA) genes.
• Transcriptome-based qualitative and quantitative analyses.
• Comparison of microbial communities in Theonella swinhoei, Plakortis simplex, Phakellia fusca, and surrounding seawater.

Main Results:

• Archaeal amoA and bacterial glnA transcripts were detected, while bacterial amoA and hzsA, and archaeal glnA transcripts were absent or below detection limits.
• Transcribed amoA genes belonged to two Thaumarchaeota ecotypes.
• Transcribed glnA genes were found across various bacterial lineages, including Cyanobacteria and multiple Proteobacteria classes.
• Significant variations in the abundance of archaeal amoA and bacterial glnA transcripts were observed among sponge species and seawater.

Conclusions:

• The study identified active ammonia-scavenging microbiota in sympatric sponges, primarily driven by archaeal amoA and bacterial glnA genes.
• Distinct phylogenetic diversity and gene expression patterns of ammonia-scavenging microbes were observed in different sponge species.
• These findings enhance the understanding of in situ microbial functions in sponge holobionts and their contribution to nitrogen cycling.