Individual Physiological Adaptations Enable Selected Bacterial Taxa To Prevail during Long-Term Incubations

Area of Science:

• Microbial Ecology
• Environmental Microbiology
• Marine Biology

Background:

• Enclosure experiments are vital for studying environmental impacts on microbial communities.
• The
• bottle effect,
• or unintended incubation impacts, on complex bacterial communities remains poorly understood.

Purpose of the Study:

• To investigate how long-term batch incubations affect bacterial communities from different salinities.
• To differentiate between manipulation-induced changes and inherent community shifts due to incubation.

Main Methods:

• Combined metaproteomic profiling, 16S rRNA gene analysis, and cell counts.
• Analyzed bacterial communities from marine, mesohaline, and oligohaline conditions.
• Compared early-phase and late-phase (55 days) incubation samples.

Main Results:

• Early in incubation, communities differed significantly, with notable responses to dissolved organic carbon manipulation.
• After 55 days, marine and mesohaline communities were dominated by *Spongiibacter*, suggesting internal carbon storage and grazing resistance as key survival traits.
• Oligohaline communities showed sustained abundance of actinobacterial cluster I (hgc-I), indicating reliance on external recalcitrant carbon.

Conclusions:

• Species-specific traits, like carbon storage strategies, can drive community shifts independently of experimental manipulations in enclosure studies.
• While enclosure experiments are valuable, the "bottle effect" necessitates critical evaluation of microbial community composition changes.
• Understanding these inherent shifts enhances the interpretation of environmental manipulation experiments.