Variation in Bat Guano Bacterial Community Composition With Depth

Bats are known to be reservoirs for a variety of mammalian pathogens, including viruses, fungi, and bacteria. Many of the studies examining the microbial community inhabiting bats have investigated bacterial taxa found within specific bat tissues and isolated bat guano pellets, but relatively few studies have explored bacterial diversity within bat guano piles. In large bat caves, bat guano can accumulate over time, creating piles several meters deep and forming complex interactions with coprophagous organisms in a habitat with low light and oxygen. As the guano decays, the nutrient composition changes, but the bacterial communities deep within the pile have not been characterized. Here, we assess the bacterial communities across varying depths within the guano pile using both culture-independent and culture-dependent methods. We found that although similar taxa are found throughout the guano pile, the relative abundances of taxa within the pile shift, allowing certain taxa to dominate the bacterial community at varying depths. We also identified potential bacterial functions being performed within the bat guano as various depths within the pile and found little variation in terms of the dominant predicted functions, suggesting that although the relative abundances of bacterial taxa are changing, the functions being performed are similar. Additionally, we cultured 15 different bacterial species, including 2 not present in our culture-independent analysis, and discuss the pathogenicity potential of these taxa. This study represents the first characterization of the bacterial community from the extreme environment within a bat guano pile and demonstrates the potential for bat caves as resources for identifying new bacterial species.

Acanthamoeba and other free-living amoebae in bat guano, an extreme habitat

Several representatives of the so-called free-living amoebae (FLA) are of medical relevance, not only as facultative pathogens but also as vehicles for pathogenic bacteria. Some FLA can survive and even grow under extreme environmental conditions. Bat guano is an exceptional habitat, the conditions becoming gradually more extreme with aging. In the current study, samples of bat guano of different ages from five caves in Slovenia were screened for the presence of FLA. FLA were isolated from almost all guano samples, including guano with a pH of 3.5. Only the two samples that had been drawn from >20-year-old guano were negative for FLA. Generally, FLA diversity correlated to high concentrations of cultivable bacteria (∼10(8) CFU/g) and fungi (∼10(5) CFU/g). Interestingly, the absence of FLA in seasoned guanos was mirrored by the presence of dictyostelid slime moulds. The isolated amoebae were identified as belonging to the genera Acanthamoeba, Copromyxa, Naegleria, Sappinia, Tetramitus, Thecamoeba, Vahlkampfia, Vannella and Vermamoeba. To the best of our knowledge, this is the first study on the diversity of FLA in guano.

Ectoparasites of neonate Indiana bats, Myotis sodalis (Chiroptera: Vespertilionidae), with description of male of Paraspinturnix globosa (Acari: Spinturnicidae)

A total of 145 ectoparasites was found on five pups of the Indiana bat, Myotis sodalis, from a roost in Warren County, in southwestern Ohio. Most were Macronyssus crosbyi, the common mite of this host, but three males, two nymphs and a nonengorged female of Paraspinturnix globosa were found. Males and nymphs of this species have not previously been reported. In addition, two female adults of Paraspinturnix globosa were found in the anus of one adult female. The male, female deutonymph and nongravid engorged female of P. globosa are described for the first time.