Airborne bacteria cultivated from underground hibernation sites in the Nietoperek bat reserve (Poland)

Abstract

The study is the first report of cultivable bacteria present in the close vicinity of hibernating bats. Samples were collected in January 2016 in one location outside the hibernation site and in five locations underground. Samples were incubated at 7 and 37 °C. Bacteria were identified based on phenotypic tests and 16S rRNA gene analysis. Air samples collected inside of underground sites contained more propagules of bacteria (from 232  28.3 to 1189  124.7 bacterial colony-forming units per m 3 of air) than outdoor air samples (42  12.2). In total, eight species of airborne bacteria belonging to three phyla and three orders were cultured from the samples. More species of airborne bacteria, eight, were isolated from the indoor underground air samples than from the outdoor air, two, especially in close vicinity to hibernating bats. Generally, Actinobacteria dominated in this study. Paeniglutamicibacter psychrophenolicus was isolated most frequently from samples incubated at 7 °C, and Micrococcus luteus from samples incubated at 37 °C. Additionally, the study was supplemented by detailed phenotypic and physiological characteristics of airborne bacteria obtained in the Nietoperek bat reserve.

Greater Mouse-Eared Bats (Myotis myotis) Hibernating in the Nietoperek Bat Reserve (Poland) as a Vector of Airborne Culturable Fungi

“…Incubation temperatures are also important for the in vitro microbiological analysis of biological material, since the temperature can influence the number and species composition of isolated microorganisms [16,74]. For example, most fungi grow well at room temperature (20-25 • C), but there are cold-adapted species, such as psychrophilic and psychrotrophic fungi, that prefer cooler temperatures [62].…”

“…Before the winter starts, M. myotis gather in large groups [14]. Both of these behaviors create an excellent opportunity to spread infectious agents, such as fungi, viruses, and/or bacteria, among individuals [15][16][17]. Bat hibernation sites are crucial to survive harsh seasonal environmental conditions, such as reduced insect availability, and are characterized by low temperatures (around 2 to 10 • C) and high relative humidity, often above 80%, allowing these animals to minimize energy expenditure [18].…”

“…The majority of infectious agents are not able to actively grow in underground ecosystems due to the low temperatures, no light, and scarcity of nutrients [16,19]. Underground sites are inhospitable places for nonresidential microbial life [20].…”

“…The skin fungal assemblages of bats vary based on their susceptibility to white-nose syndrome [37]. Unfortunately, there is still a lack of comprehensive data on airborne fungi related to specific species of bats, with only two reports published about bat hibernation sites in relation to airborne fungi [10,15] and one report about a bat hibernation site in relation to airborne bacteria [16]. These first two studies showed that bats are the main vector/reservoir of airborne fungi such as Aspergillus and Penicillium species in underground ecosystems in Western Poland and Northeastern Brazil [10,15].…”

A Culture-Based ID of Micromycetes on the Wing Membranes of Greater Mouse-Eared Bats (Myotis myotis) from the “Nietoperek” Site (Poland)

“…Out of 12 bat species found hibernating in the "Nietoperek", four are mentioned in Annex II of the EU Habitat Directive. More detailed descriptions of the "Nietoperek" bat reserve is given in our previous publications [9,42,43].…”