Chemical regulation of body feather microbiota in a wild bird

Abstract

The microbiota has a broad range of impacts on host physiology and behaviour, pointing out the need to improve our comprehension of the drivers of host-microbiota composition. Of particular interest is whether the microbiota is acquired passively, or whether and to what extent hosts themselves shape the acquisition and maintenance of their microbiota. In birds, the uropygial gland produces oily secretions used to coat feathers that have been suggested to act as an antimicrobial defence mechanism regulating body feather microbiota. However, our comprehension of this process is still limited. In this study, we for the first time coupled high-throughput sequencing of the microbiota of both body feathers and the direct environment (i.e., the nest) in great tits with chemical analyses of the composition of uropygial gland secretions to examine whether host chemicals have either specific effects on some bacteria or nonspecific broad-spectrum effects on the body feather microbiota. Using a network approach investigating the patterns of co-occurrence or co-exclusions between chemicals and bacteria within the body feather microbiota, we found no evidence for specific promicrobial or antimicrobial effects of uropygial gland chemicals. However, we found that one group of chemicals was negatively correlated to bacterial richness on body feathers, and a higher production of these chemicals was associated with a poorer body feather bacterial richness compared to the nest microbiota. Our study provides evidence that chemicals produced by the host might function as a nonspecific broad-spectrum antimicrobial defence mechanism limiting colonization and/or maintenance of bacteria on body feathers, providing new insight about the drivers of the host's microbiota composition in wild organisms.

Does solar irradiation drive community assembly of vulture plumage microbiotas?

“…A significant fraction (13.5%) of the 631 bacterial and archaeal genera detected in the 16S rRNA survey were taxonomically unclassified in SILVA database [51]. More than 70% of the bacterial and archaeal genera detected in our analyses have not been previously reported in the associated tables and appendices of published papers that investigated plumage microbiota with 16S rRNA sequencing [5,6,[17][18][19][20][21][22][23][24]27]. Vulture plumage microbiotas can accurately be described as hyper-diverse and taxonomically cryptic.…”

“…Microbial keratinases target cross-linked structural peptides that make feather keratin insoluble [15]. The continued focus on domestic poultry and keratinolytic bacteria has resulted in a substantial void in our knowledge of the taxonomic diversity, host specificity, and assembly of microbial communities in the plumage of the 10,135 wild bird species [5,6,[17][18][19][20][21][22][23][24][25][26][27][28].…”

Olfactory Communication via Microbiota: What Is Known in Birds?

“…Studies on bird feathers show that they harbour a substantial amount of bacteria on their surface [ 34 , 35 ] with some of them being capable to degrade the feather substance [ 36 ]. Microbiota may be regulated by substances deriving from the uropygial gland secretion ([ 37 ], reviewed in [ 38 ]) and feather-degrading bacteria could be involved in odour production via breaking down feather components into small, possibly volatile, fragments. Because of their extended surface, feathers offer a great surface for odours to emerge from a bird, however, to the best of our knowledge, thus far no study has investigated this possibility.…”

“…Secondly, birds use secretion from the uropygial gland to preen their feathers, which is most likely involved in both, olfactory communication [ 135 , 136 , 137 ] and maintaining the stability of the surface microbial community [ 37 , 138 ]. This gives the possibility for microbial interactions at different stages and locations and for selection to act at different stages i.e., already in the preen gland, on the feathers, skin, gut and/or cloaca.…”

Interspecific variation in deterioration and degradability of avian feathers: the evolutionary role of microorganisms

“…Within nests, the bacterial environment would largely determine feather bacterial loads (Jacob et al ) and, thus, risk of bacterial degradation of feathers. Nest bacterial environment are largely determined by the behaviour of parents including those related to nest building (e.g.…”