Phosphorus Accumulation in Extracellular Polymeric Substances (EPS) of Colony-Forming Cyanobacteria Challenges Imbalanced Nutrient Reduction Strategies in Eutrophic Lakes

Abstract

Extracellular polymeric substances (EPS) are crucial for cyanobacterial proliferation; however, certain queries, including how EPS affects cellular nutrient processes and what are the implications for nutrient management in lakes, are not well documented. Here, the dynamics of cyanobacterial EPS-associated phosphorus (EPS-P) were examined both in a shallow eutrophic lake (Lake Taihu, China) and in laboratory experiments with respect to nitrogen (N) and phosphorus (P) availability. Results indicated that 40−65% of the total cyanobacterial aggregate/particulate P presented as EPS-P (mainly labile P and Fe/Al-P). Phosphorus-starved cyanobacteria rapidly replenished their EPS-P pools after the P was resupplied, and the P concentration in this pool was stable for long afterward, although the environmental P concentration decreased dramatically. A low-N treatment enhanced the EPS production alongside two-fold EPS-P accumulation (particularly labile P) higher than the control. Such patterns occurred in the lake where EPS and EPS-P contents were high under N limitation. EPS-P enrichment increased the P content in cyanobacteria; subsequently, it could hold the total P concentration higher for longer and make bloom mitigation harder. The findings outline a new insight into EPS functions in the P process of cyanobacterial aggregates and encourage consideration of both N and P reductions in nutrient management.

Microbial colonization patterns and biodegradation of petrochemical and biodegradable plastics in lake waters: insights from a field experiment

“…The presence of Rhodobacteriaceae on PET, Cyanobiaceae on LDPE and PLA, along with microalgae and diatoms in all the polymers tested, might provide a further attachment substratum for bacteria. Biofilm-forming cyanobacteria and diatoms are known to highly contribute to EPS secretion ( Duan et al, 2023 ; Raghavan et al, 2023 ; Romeu et al, 2023 ; Zackova Suchanova et al, 2023 ), decreasing the chance for the bacterial populations, including those potentially suitable to degrade polymers, to be in direct contact with plastic surfaces. Moreover, Cyanobacteria and microalgae provide assimilable organic matter (e.g., photosynthates, EPS) ( Underwood and Paterson, 2003 ), that is more likely to be used as growth substrate than carbon of plastic materials.…”

Hot spring diatoms are linked to extreme cold conditions: A new perspective for astrobiological implication from the sinter deposit of Puga hot spring, Ladakh, India

“…4c). This P enrichment might be attributed to the presence of microbial EPS (Duan et al, 2023;Zhou et al, 2017) on the sinter. Furthermore, the presence of Mg in the sample suggests that EPS produced by bacteria include organic molecules that accelerate the incorporation of Mg in the carbonate mineral (Al Disi et al, 2019).…”