A
Associate Professor
Institute of Conservation
Michela Gambino
Associate professor at the Institute of Conservation, I am trained both as a heritage conservator and a microbiologist and molecular biologist. My multidisciplinary track record spans from heritage conservation to microbiology, phage biology and microbiome of soil, wastewater and animal gastrointestinal tract. I am studying how microorganisms interact with each other, with materials and with us.
Michela Gambino
The Assistens kirkegård project
Introduction and objectives
Stone monuments worldwide are endangered by multiorganism biofilms, well-structured communities of bacteria, fungi and algae, enclosed in a protective matrix. Biofilms can be particularly problematic when the monument is outdoors, because of limited or no possibility of controlling climate, and thus the biofilms' growth. To protect our cultural heritage, conservators clean the monuments, but biofilms promptly grow back. To design more effective and sustainable solutions, we need to understand how multiorganisms biofilms response to treatments and to environmental changes will affect the stone monuments.
By studying multiorganism biofilms colonizing six historical stone monuments, we aim to propose an ecological model of organisms succesion on monuments, and to answer the following questions:
1) which pioneer species survive the conservation treatments?
2) how do biofilms respond to the environment and change with time, and which species ensure its stability (keystone)?
3) how do bacteria, fungi and algae organize in a biofilm and how they interact with monuments?
Methods
Here, we use a longitudinal study (September 2023 to August 2024) to describe and monitor the evolution of bacterial and fungal biofilms colonizing the stone surface of six tombstones at the Assistens Cementery in Copenhagen. With a conservation treatment in October 2023, the biofilm was removed from the six tombstones, but it is expected to grow again in few years. To monitor the biofilm development and identify the pioneer species, we collected samples for microbiome analysis just before the treatment and for a year after, every two months. Light, temperature and humidity has been measured at each sampling points and environmental parameters were recorded continuously for a year in the Cemementery. In addition, pre-conservation samples have been processed for isolation of phototropic and heterotrophic microorganisms to reproduce multiorganism biofilms in the laboratory and investigate strategies for biofilm removal with high throughput screening techniques.
Findings and perspectives
Biofilms colonizing the analyzed stone monuments stones are complex communities of both phototrophic and heterotrophic microorganisms, supporting each other metabolism and resilience to stress. From pre-conservation treatment samples, we could isolate, store and taxonomically identify 18 fungi, 14 bacteria and 17 algae from the six tombstones. We are now processing all samples collected at six time point during one year for metagenomic analysis (16S for bacteria, ITS for fungi and 18S for algae) in order to identify the pioneer species that survive the conservation treatments and reproduce and validate the observation in the laboratory with multiorganism biofilms growing on stone mockup samples. Metagenomic data will be also used to identify specific time point to further process with shotgun sequencing and add details to identify keystone species and gaining insights on the interaction between biofilms, environment and material.
Conclusion: The project is expected to shed light on the interactions within multiorgansims biofilms and in response to environmental changes and conservation treatments. we will link the acclimation and evolution of multiorganism biofilms with material deterioration and investigate their resistance to treatments for biodeteriogens removal and inactivation, currently used in conservation.
We are proceeding with studying the sensitivity to temperature and commonly used biocides of each isolated microorganism
Each fungal, bacterial and algal species growing has been isolated and identified.