INVISIBLE INHABITANTS: MICROBIOTA ON THE SURFACE OF DORMANT ZOOPLANKTON EMBRYOS

Dormant zooplankton embryos in inland water and estuarine sediment can remain viable for years in a state of extreme metabolic suppression. How these embryos resist microbial attack with limited metabolic capacity for immune defense or repair is unknown. An active defense against microbes requires metabolic activity, which they lack. Evaluating surface colonization of the Antarctic freshwater copepod, Boeckella poppei, was conducted as a first step in assessing resistance to microbial attack in dormant zooplankton. Scanning electron microscopy and microbiome analysis using the 16S ribosomal subunit gene and internal transcribed spacer (ITS) region, demonstrate the presence of a diverse microbial community on the embryo surface. Coverage of embryos with microbial life varies from a sparse population with individual microbes to complete coverage by a thick biofilm. Prokaryotes and diatoms with diverse physical structure are present. Putative fungal hyphae and amoeboid-like organisms were also observed. Frequent observation of bacterial fission indicates that the biofilm is viable in stored sediments. Extracellular polymeric substance binds debris and provides a structural element for the microbial community. Unexpectedly, previously undescribed layers of the cyst wall in B. poppei were identified. These outer layers fragment and create a complex environment for microbial colonization. The absence of damage to the underlying third layer after years of storage indicates that it is resistant to degradation by microbial enzymes, which should be of interest to material scientists.

Presentation Preference: Oral

Primary Presenter: Hunter Arrington, University of North Carolina Wilmington (hba4881@uncw.edu)

Authors:

Hunter Arrington, University of North Carolina Wilmington  (hba4881@uncw.edu)

Joseph Covi, Univeristy of North Carolina Wilmington  (covij@uncw.edu)

Katherine Reed, University of North Carolina Wilmington  (reedk@uncw.edu)

SungGu Lee, Korea Polar Research Institute/Division of Polar Life Science  (holynine@kopri.re.kr)

Jun Hyuck Lee, Korea Polar Research Institute/Division of Polar Life Science  (junhyucklee@kopri.re.kr)