Influence of hand rearing and bird age on the fecal microbiota of the critically endangered kakapo

The impact of management on the fecal microbiome of endangered greater sage-grouse (Centrocercus urophasianus) in a zoo-based conservation program

Greater sage-grouse (Centrocercus urophasianus) are a critically endangered species in Canada with fewer than 140 individuals remaining on native habitats in southern Alberta and Saskatchewan. In 2014, the Wilder Institute/Calgary Zoo initiated North America's only zoo-based conservation breeding program for this species to bolster declining wild populations through conservation reintroductions. Within the managed population of sage-grouse, morbidity and mortality have primarily been associated with intestinal bacterial infections. As a preliminary study to assess the gastrointestinal health of this species in managed care, the fecal bacterial microbiome of adult and juvenile captive sage-grouse was characterized with 16S rRNA sequencing. The composition of the microbiome at the phylum level in greater sage-grouse is consistent with previous studies of the avian microbiome, with Bacillota as the most abundant phyla, and Actinomycetota, Bacteroidota and Pseudomonadota also being highly abundant. Antibiotic use and sex did not have a significant impact on the diversity or composition of the microbiome, but the management of juvenile sage-grouse did influence the development of the microbiome. Juveniles that were raised outdoors under maternal care developed a microbiome much more similar to adults when compared to chicks that were incubated and hand-raised. The local environment and parental care appear to be important factors influencing the diversity and composition of the gastrointestinal microbiome in this species.

Gut microbiota of skywalker hoolock gibbons (Hoolock tianxing) from different habitats and in captivity: Implications for gibbon health

The gut microbiota plays an integral role in the metabolism and immunity of animal hosts, and provides insights into the health and habitat assessment of threatened animals. The skywalker hoolock gibbon (Hoolock tianxing) is a newly described gibbon species, and is considered an endangered species. Here, we used 16S rRNA amplicon sequencing to describe the fecal bacterial community of skywalker hoolock gibbons from different habitats and in captivity. Fecal samples (n = 5) from two captive gibbons were compared with wild populations (N = 6 gibbons, n = 33 samples). At the phylum level, Spirochetes, Proteobacteria, Firmicutes, Bacteroidetes dominated in captive gibbons, while Firmicutes, Bacteroidetes, and Tenericutes dominated in wild gibbons. At the genus level, captive gibbons were dominated by Treponema-2, followed by Succinivibrio and Cerasicoccus, while wild gibbons were dominated by Anaeroplasma, Prevotellaceae UCG-001, and Erysipelotrichaceae UCG-004. Captive rearing was significantly associated with lower taxonomic alpha-diversity, and different relative abundance of some dominant bacteria compared to wild gibbons. Predicted Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that captive gibbons have significantly lower total pathway diversity and higher relative abundance of bacterial functions involved in "drug resistance: antimicrobial" and "carbohydrate metabolism" than wild gibbons. This study reveals the potential influence of captivity and habitat on the gut bacterial community of gibbons and provides a basis for guiding the conservation management of captive populations.

Influence of management practice on the microbiota of a critically endangered species: a longitudinal study of kākāpō chick faeces and associated nest litter

BACKGROUND

The critically endangered kākāpō is a flightless, nocturnal parrot endemic to Aotearoa New Zealand. Recent efforts to describe the gastrointestinal microbial community of this threatened herbivore revealed a low-diversity microbiota that is often dominated by Escherichia-Shigella bacteria. Given the importance of associated microbial communities to animal health, and increasing appreciation of their potential relevance to threatened species conservation, we sought to better understand the development of this unusual gut microbiota profile. To this end, we conducted a longitudinal analysis of faecal material collected from kākāpō chicks during the 2019 breeding season, in addition to associated nest litter material.

RESULTS

Using an experimental approach rarely seen in studies of threatened species microbiota, we evaluated the impact of a regular conservation practice on the developing kākāpō microbiota, namely the removal of faecal material from nests. Artificially removing chick faeces from nests had negligible impact on bacterial community diversity for either chicks or nests (p > 0.05). However, the gut microbiota did change significantly over time as chick age increased (p < 0.01), with an increasing relative abundance of Escherichia-Shigella coli over the study period and similar observations for the associated nest litter microbiota (p < 0.01). Supplementary feeding substantially altered gut bacterial diversity of kākāpō chicks (p < 0.01), characterised by a significant increase in Lactobacillus bacteria.

CONCLUSIONS

Overall, chick age and hand rearing conditions had the most marked impact on faecal bacterial communities. Similarly, the surrounding nest litter microbiota changed significantly over time since a kākāpō chick was first placed in the nest, though we found no evidence that removal of faecal material influenced the bacterial communities of either litter or faecal samples. Taken together, these observations will inform ongoing conservation and management of this most enigmatic of bird species.

The avian gut microbiota: Diversity, influencing factors, and future directions

The gut microbiota is viewed as the “second genome” of animals, sharing intricate relationships with their respective hosts. Because the gut microbial community and its diversity are affected by many intrinsic and extrinsic factors, studying intestinal microbes has become an important research topic. However, publications are dominated by studies on domestic or captive birds, while research on the composition and response mechanism of environmental changes in the gut microbiota of wild birds remains scarce. Therefore, it is important to understand the co-evolution of host and intestinal bacteria under natural conditions to elucidate the diversity, maintenance mechanisms, and functions of gut microbes in wild birds. Here, the existing knowledge of gut microbiota in captive and wild birds is summarized, along with previous studies on the composition and function, research methods employed, and factors influencing the avian gut microbial communities. Furthermore, research hotspots and directions were also discussed to identify the dynamics of the avian gut microbiota, aiming to contribute to studies of avian microbiology in the future.

Effects of floor- and net-rearing systems on intestinal growth and microbial diversity in the ceca of ducks

BACKGROUND

Rearing systems can affect livestock production directly, but whether they have effects on intestinal growth states and ceca microorganisms in ducks is largely unclear. The current study used Nonghua ducks to estimate the effects of rearing systems on the intestines by evaluating differences in intestinal growth indices and cecal microorganisms between ducks in the floor-rearing system (FRS) and net-rearing system (NRS).

RESULTS

The values of relative weight (RW), relative length (RL) and RW/RL of the duodenum, jejunum, ileum and ceca in the FRS were significantly higher than those in the NRS during weeks 4, 8 and 13 (p < 0.05). A total of 157 genera were identified from ducks under the two systems, and the dominant microorganisms in both treatments were Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria at the phylum level. The distribution of microorganisms in the ceca of the two treatments showed significant separation during the three time periods, and the value of the Simpson index in the FRS was significantly higher than that in the NRS at 13 weeks (p < 0.05). Five differential microorganisms and 25 differential metabolic pathways were found in the ceca at week 4, seven differential microorganisms and 25 differential metabolic pathways were found in the ceca at week 8, and four differential microorganisms and two differential metabolic pathways were found in the ceca at week 13.

CONCLUSIONS

The rearing system influences duck intestinal development and microorganisms. The FRS group had higher intestinal RL, RW and RW/RL and obviously separated ceca microorganisms compared to those of the NRS group. The differential metabolic pathways of cecal microorganisms decreased with increasing age, and the abundance of translation pathways was higher in the NRS group at week 13, while cofactor and vitamin metabolism were more abundant in the FRS group.

Gut microbiota of the threatened takahē: biogeographic patterns and conservation implications

BACKGROUND

The Aotearoa New Zealand takahē (Porphyrio hochstetteri), once thought to be extinct, is a nationally threatened flightless rail under intensive conservation management. While there has been previous research into disease-related microbes in takahē, little is known about the microbes present in the gastrointestinal tract. Given the importance of gut-associated microbes to herbivore nutrition and immunity, knowledge of these communities is likely to be of considerable conservation value. Here we examined the gut microbiotas of 57 takahē at eight separate locations across Aotearoa New Zealand.

RESULTS

Faecal samples, taken as a proxy for the hindgut bacterial community, were subjected to 16S rRNA gene amplicon sequencing using Illumina MiSeq. Phylogenetic analysis of > 2200 amplicon sequence variants (ASVs) revealed nine main bacterial phyla (Acidobacteriota, Actinobacteriota, Bacteroidota, Campilobacterota, Firmicutes, Fusobacteriota, Planctomycetota, Proteobacteria, and Verrucomicrobiota) that accounted for the majority of sequence reads. Location was a significant effect (p value < 0.001, 9999 permutations) that accounted for 32% of the observed microbiota variation. One ASV, classified as Lactobacillus aviarius, was present in all samples at an average relative abundance of 17% (SD = 23.20). There was strong evidence (p = 0.002) for a difference in the abundance of the genus Lactobacillus between locations. A common commensal bacterium previously described in takahē, Campylobacter spp., was also detected in most faecal samples.

CONCLUSIONS

Location plays a pivotal role in the observed variation among takahē gut bacterial communities and is potentially due to factors such as supplemental feeding and medical treatment experienced by birds housed in captivity at one of the eight sampled sites. These data present a first glimpse of the previously unexplored takahē gut microbiota and provide a baseline for future microbiological studies and conservation efforts.

Gut microbiota of endangered crested ibis: Establishment, diversity, and association with reproductive output

Gut microbiota is known to influence the host’s health; an imbalance of the gut microbial community leads to various intestinal and non-intestinal diseases. Research on gut microbes of endangered birds is vital for their conservation. However, a thorough understanding of the gut microbiome composition present in crested ibises at different ages and its correlation with crested ibis reproductive capacity has remained elusive. Here, we used 16S rRNA gene sequencing to explore the fecal microbial structure of nestlings and adult birds, and the difference in gut microbiota between healthy and sterile crested ibises. We observed that (1) bacterial microbiota, alpha and beta diversity of one-day-old nestlings significantly distinguished from other nestlings; abundance of Proteobacteria decreased, while that of Fusobacteria increased with an increase in the age of the nestlings; (2) there was no significant difference in community composition among adult crested ibises aged one, two, three, and five years; (3) the abundance of Proteobacteria and alpha diversity indices were higher in sterile crested ibises than in healthy crested ibises; thus, Proteobacteria can act as a diagnostic biomarker of reproductive dysfunction in crested ibises. This study significantly contributes to the field of ecology and conservation, as it provides a platform for assessing the reproductive capacity of endangered crested ibises, based on the gut microbiota composition. Further studies may unravel additional factors influencing crested ibises’ reproductive health, which will further help the management and control of the crested ibis population.

Comparative Analysis of Gut Microbiota in Captive and Wild Oriental White Storks: Implications for Conservation Biology

The oriental white stork (Ciconia boyciana) is considered an endangered species based on the International Union for Conservation of Nature (IUCN) Red List. This study presents the first evidence on comparative analysis of gut microbial diversity of C. boyciana from various breeding conditions. To determine the species composition and community structure of the gut microbiota, 24 fecal samples from Tianjin Zoo and Tianjin Qilihai Wetland were characterized by sequencing 16S rRNA gene amplicons using the Illumina MiSeq platform. Firmicutes was found to be the predominant phylum. Analysis of community structure revealed significant differences in the species diversity and richness between the populations of the two breeding conditions. The greatest α-diversity was found in wild C. boyciana, while artificial breeding storks from Tianjin Zoo had the least α-diversity. Principal coordinates analysis showed that the microbial communities were different between the two studied groups. In conclusion, this study reveals the species composition and structure of the gut microbiota of oriental white storks under two breeding conditions, and our findings could contribute to the integrative conservation of this endangered bird.

The Composition of Gut Microbiota Community Structure of Jankowski's Bunting (Emberiza jankowskii)

Gut microbiota play a central role in the health of animals. The bacteria that individuals acquire as they age may therefore have a profound effect on their future fitness. Since most birds are capable of flight, they can be widely distributed in and adapted to various ecosystems. Moreover, birds are also challenged by the need to digest a wide range of food resources in their guts. However, little is known regarding how the microbial community structure in birds, especially wild birds, changes with host age. Here, we used high-throughput sequencing of the 16S rRNA V3-V4 region to depict the microbial composition and structure in the adults and nestlings of Jankowski's bunting (Emberiza jankowskii), an endangered species of bird, during the breeding season. The results showed that the phyla Proteobacteria (52.45%), Firmicutes (13.87%), Bacteroidetes (5.76%), Actinobacteria (4.95%), Planctomycetes (4.36%), Euryarchaeota (3.20%), Acidobacteria (2.59%), Fusobacteria (2.24%), and Chloroflexi (1.8%) dominated the gut microbial communities in Jankowski's bunting. There was no significant difference in the alpha diversity and richness among different age groups. There was also no significant difference in species richness and diversity between the nestlings and adults. However, we observed different bacterial compositions at the genus level. The genera Photobacterium and Brochothrix were detected only in the nestling groups (at days 3, 6, and 9), while Diplorickettsia was detected only in the adult group. In summary, this study can provide additional information regarding the intestinal microorganisms of wild passerine and grassland birds and provide theoretical evidence for methods to protect Jankowski's bunting.

16S rRNA gene sequencing reveals the relationship between gut microbiota and ovarian development in the swimming crab Portunus trituberculatus

Gut microbiota executes many beneficial functions. In this study, the relationship between gut microbiota and ovarian development in the swimming crab P. trituberculatus was explored for the first time. A total of 28 phyla and 422 genera were identified across all samples. However, 105 differential operational taxonomic units, and four differential phyla (Gemmatimonadetes, Actinobacteria, Firmicutes, Marinimicrobia_(SAR406_clade)) were identified. At the genus level, 42 differential genera were identified and 144 bacterial indicators were identified. A key finding was that the relative abundance of 139 indicator bacteria detected in the anisomycin-2 mg/kg group (AK group) was higher than that of blank group (BK group), control group (CK group), SP600125-15 mg/kg group (SK group). In addition, the relative abundance of three indicator bacteria (OTU_236, OTU_1395, OTU_552) detected in the SK group was higher than that of the BK, CK and AK groups. It was also found that the relative abundance of 20 differential genera (Methyloversatilis, Coprococcus_1, Erysipelotrichaceae_UCG_003, Rikenella, Corynebacterium, Ruminiclostridium, Fusicatenibacter, [Eubacterium]_ruminantium_group, Rikenellaceae_RC9_gut_group, Bifidobacterium, Lachnospiraceae_NK4A136_group, Ruminococcaceae_UCG_014, Christensenellaceae_R_7_group, uncultured_Bacteroidales_bacterium, Coprococcus_2, Desulfovibrio, Aggregatibacter, Ambiguous_taxa, Alloprevotella and Ruminococcaceae_NK4A214_group) in the SK, BK, CK, and AK group samples were increasing. These differential genera may reveal the relationship between gut microbial communities and ovarian development in P. trituberculatus after injection with the JNK pathway inhibitor SP600125 or the activator anisomycin. In summary, this study provides a new understanding into the relationship between gut microbiota and ovarian development in response to stimulation with inhibitor or activator.

The fecal microbiota of wild and captive raptors

BACKGROUND

The microorganisms populating the gastro-intestinal tract of vertebrates, collectively known as "microbiota", play an essential role in digestion and are important in regulating the immune response. Whereas the intestinal microbiota in humans and model organisms has been studied for many years, much less is known about the microbiota populating the intestinal tract of wild animals.

RESULTS

The relatively large number of raptors admitted to the Tufts Wildlife Clinic on the Cummings School of Veterinary Medicine at Tufts University campus provided a unique opportunity to investigate the bacterial microbiota in these birds. Opportunistic collection of fecal samples from raptors of 7 different species in the orders Strigiformes, Accipitriformes, and Falconiformes with different medical histories generated a collection of 46 microbiota samples. Based on 16S amplicon sequencing of fecal DNA, large β-diversity values were observed. Many comparisons exceeded weighted UniFrac distances of 0.9. Microbiota diversity did not segregate with the taxonomy of the host; no significant difference between microbiota from Strigiformes and from Accipitriformes/Falconiformes were observed. In contrast, in a sample of 22 birds admitted for rehabilitation, a significant effect of captivity was found. The change in microbiota profile was driven by an expansion of the proportion of Actinobacteria. Based on a small number of raptors treated with anti-microbials, no significant effect of these treatments on microbiota α-diversity was observed.

CONCLUSIONS

The concept of "meta-organism conservation", i.e., conservation efforts focused on the host and its intestinal microbiome has recently been proposed. The observed effect of captivity on the fecal microbiota is relevant to understanding the response of wildlife to captivity and optimizing wildlife rehabilitation and conservation efforts.

Muscovy Duck Reovirus Infection Disrupts the Composition of Intestinal Microbiota in Muscovy Ducklings

Muscovy duck reovirus (MDRV) is highly pathogenic to young Muscovy ducklings. Although MDRV infection results in ducklings' acute watery diarrhea, the effect of MDRV infection on the composition of host's intestinal microbiota remains poorly understood. This study was conducted to investigate the impacts of MDRV on the composition of Muscovy ducklings' intestinal bacterial community. Three-day-old Muscovy ducklings were inoculated with either the virulent MDRV strain MW9710 or sterile Hank's solution, respectively. The cecal microbiota was analyzed between control and mock MDRV-infected ducklings using Illumina MiSeq sequencing at 6 dpi and 17 dpi, respectively. The results indicated that MDRV infection damaged the intestinal mucosa. In addition, MDRV infection caused severe perturbations of gut microbiota by decreasing microbial richness, altering the abundance of certain genera of the gut microbiota at 6 dpi. Specifically, the relative abundance of short chain fatty acids-producing bacteria (including Shuttleworthia, Streptococcus, and Ruminococcus) was reduced in MDRV-infected ducklings than those of control group, whereas, with an enrichment of Enterobacteriaceae (including Plesiomonas, Escherichia_Shigella and Proteus). Furthermore, microbiota analysis showed that the gut microbiota dysbiosis caused by MDRV infection was basically recovered at 17 dpi. Collectively, this study demonstrated that the gut microbiota of Muscovy ducklings were altered due to MDRV infection, mainly featuring as a net loss of beneficial bacteria and a compensatory proliferation of pathogenic bacteria, which may lead to severe pathology to the intestinal mucosa, and ultimately acute diarrhea. These results will provide insights into the pathology of MDRV infection.

Characterization of the gut microbiome of black-necked cranes (Grus nigricollis) in six wintering areas in China

The black-necked crane (Grus nigricollis) is a vulnerable species, breeding exclusively on the high-altitude wetlands of the Qinghai-Tibet Plateau. Bird species harbor diverse communities of microorganisms within their gastrointestinal tracts, which have important roles in the health, nutrition, and physiology of birds. Hitherto, virtually nothing was known about the gut microbial communities associated with wild black-necked cranes. For the first time, this study characterized the gut microbial community compositions, diversity, and functions of black-necked cranes from six wintering areas in China using the Illumina Miseq platform. The taxonomic results revealed that Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes were the four most abundant phyla in the gut of black-necked cranes. At the genus level, 11 genera including Lactobacillus, Pseudomonas, Carnobacterium, Pantoea, Enterococcus, Erwinia, Turicibacter, Bacillus, Phenylobacterium, Sanguibacter, and Psychrobacter were dominant. The differences in the gut microbial community alpha and the beta diversities of black-necked cranes among the six wintering areas were investigated. Furthermore, the representative microbial taxa and their predicted functions in each wintering location were also determined. These data represent the first analysis of the gut microbiome of black-necked cranes, providing a baseline for further microbiological studies and a foundation for the conservation of this bird.

Characterization of the microbiome along the gastrointestinal tracts of semi-artificially reared bar-headed geese (Anser indicus)

As one of the dominant waterfowl species of wetland areas in the Qinghai-Tibet Plateau, since 2003, artificial rearing of bar-headed geese (Anser indicus) has increased in several provinces of China for the purpose of conservation and economic development. In this study, we systematically characterized the microbial community diversity, compositions and predicted functions of semi-artificially reared bar-headed geese by sampling five different gut locations (the oropharynxs, crops, gizzards, ceca, and cloacae) along the gastrointestinal tracts of three individuals. Alpha diversity analyses showed that the gizzards had the richest species diversity and that the ceca had the least. Beta diversity analyses showed that the cecal samples formed their own cluster, while samples from the oropharynxs, crops, gizzards, and cloacae overlapped with each other. At the phylum level, Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Fusobacteria constituted the top five dominant phyla among all five gastrointestinal sections. At the genus level, a total of 10 genera with proportions above 2.5% were found to be significantly different among the gastrointestinal sections. Furthermore, 53 genera were detected in all gastrointestinal sections of bar-headed geese. PICRUSt data also predicted a group of microbial functions overrepresented in the different segments of the gastrointestinal tracts. Understanding the microbiota along the bar-headed geese gastrointestinal tracts is essential for future microbiological study of this bird and may contribute to the development of geese husbandry.

High-throughput sequencing reveals the core gut microbiota of the mud crab (Scylla paramamosain) in different coastal regions of southern China

Background

Scylla paramamosain is a commercially important mud crab. The microbiota is a community that inhabits the crab intestine, and is important for physiological functional and host health.

Results

Proteobacteria, Firmicutes, Bacteroidetes, Tenericutes, Spirochaetae and Fusobacteria were the dominant phyla of the 36 representative phyla. Eleven genera of the 820 representative genera were considered as core gut microbiota and were distributed in the five dominant phyla. The core genus of the Proteobacteria included Arcobacter, Photobacterium, Vibrio, Shewanella and Desulfovibrio. The other four phyla contained one or two genera. Male and female crab samples had two different core genera, (male samples: Psychrilyobacter & Lactococcus; female samples: Clostridium_sensu_stricto_11 and Candidatus_Bacilloplasma).

Conclusions

This is the first time core intestinal microbiota have been identified in crab from nine coastal regions of southern China. This study provides sequencing data related to the gut microbiota of S. paramamosain, and may contribute to probiotic development for S. paramamosain aquaculture industries.

Analysis of the Gut Microbiome of Wild and Captive Père David's Deer

Père David’s deer (Elaphurus davidianus or milu) is a highly endangered species originating from China, and many deer are currently being raised in captivity for gradual re-introduction to the wild. Wild and captive deer currently live in the same region but have vastly different diets. In this study, we used 16S rRNA high-throughput sequencing to identify the healthy core microbiome in the gut of wild and captive Père David’s deer and investigate how dietary factors influence the gut microbiome by comparing their differences. A core shared gut microbiome was identified in healthy Père David’s deer, which was similar to that of other ruminants, mainly comprising the phyla Firmicutes and Bacteroidetes. There were no differences in the richness or diversity of the gut microbiome between the wild and captive deer. However, PCA and ANOSIM demonstrated clear differences in the microbial community structure between the captive and wild deer, which mainly manifested as changes in the relative abundance of 39 bacterial genera. As the majority of these genera were not dominant in the deer gut, no significant difference was detected in functional modules related to the microbiome between the two groups. Therefore, the difference in dietary factors does not appear to affect the healthy core gut microbiome between captive and wild Père David’s deer, suggesting strong co-evolution and the possibility of re-establishment in the wild. These data could guide future applications of population management in Père David’s deer conservation.

Composition, diversity and function of gastrointestinal microbiota in wild red-billed choughs (Pyrrhocorax pyrrhocorax)

Hitherto, virtually nothing is known about the microbial communities related to the bird species in the family Corvidae. To fill this gap, the present study was conducted to provide a baseline description of the gut microbiota of wild red-billed choughs (Pyrrhocorax pyrrhocorax). In this study, microbiota from four gastrointestinal locations (oropharynx, gizzard, small intestine, and large intestine) of three wild red-billed choughs were analyzed using the Illumina MiSeq sequencing platform by targeting the V4-V5 regions of the 16S rRNA genes. The gut microbiota of the red-billed choughs were dominated by the phylum Firmicutes (59.56%), followed by Proteobacteria (16.56%), Bacteroidetes (13.86%), and Actinobacteria (7.03%), which were commonly detected in avian gut ecosystems. Genus-level compositions were found to be largely dominated by Lactobacillus (18.21%), Weissella (12.37%), Erysipelatoclostridium (6.94%), Bacteroides (6.63%), Escherichia-Shigella (5.15%), Leuconostoc (4.60%), Proteus (3.33%), Carnobacterium (2.71%), Lactococcus (1.69%), and Enterococcus (1.63%). The overall intestinal microbiota was enriched with functions related to ATP-binding cassette (ABC) transporters, DNA repair and recombination proteins, purine metabolism, ribosome, transcription factors, pyrimidine metabolism, peptidases, and two-component system. In terms of four different gastrointestinal locations, hierarchical clustering analysis and principal coordinate analysis showed that microbial communities of the oropharynx, gizzard, small intestine, and large intestine formed four separated clusters. A total of 825 OTUs and 382 genera were detected in all four gastrointestinal locations, which were considered as the major microbes in the intestines of red-billed choughs. Coexistence of lactic acid bacteria and potential pathogens in the gut environments of red-billed choughs required further investigations.

Age-related variation in the oral microbiome of urban Cooper's hawks (Accipiter cooperii)

Background

Bird species worldwide are affected by trichomoniasis caused by the protist Trichomonas gallinae. In avivorous raptors such as Cooper’s hawks (Accipiter cooperii), nestlings are more susceptible than fledglings and adults. Previous research suggested a link between oral pH and susceptibility: the oral pH of fledgling and adult hawks is more than seven times more acidic than that of nestlings. We speculated that this age-specific difference in pH would correspond to age-specific differences in the oral microbiota of Cooper’s hawks. We examined the oral microbiomes of 31 healthy, wild Cooper’s hawks in Tucson, Arizona (USA). Individuals represented three age classes (nestlings, fledglings, and adults). We designed our study with multiple controls, replicated sampling, mock communities, and stringent quality-controls to address challenges that can limit the inferential quality of microbiome data sets.

Results

Richness of bacterial communities in oral cavities of Cooper’s hawks differed as a function of age but not as a function of sex, sampling date, or sampling location. Bacterial communities in oral cavities of nestlings differed from those of fledglings and adults, whereas communities in fledglings and adults did not differ from each other. Communities were similar in males and females and did not differ over the sampling season. Prevalence of acid-producing bacteria in fledgling and adults vs. nestlings is consistent with previous reports of age-specific variation in oral pH, but further research is needed to establish a causal link to pH levels or susceptibility to disease. Analyses of mock communities demonstrated high repeatability and showed that operon number and read abundance were highly correlated.

Conclusions

The oral microbiota of wild Cooper’s hawks differs between nestlings and older birds. Variation in the oral microbiome is consistent with differences in oral pH between nestlings and older individuals. Overall our study provides a first perspective on bacterial communities associated with oral cavities of a wild raptor.

Electronic supplementary material

The online version of this article (10.1186/s12866-019-1413-y) contains supplementary material, which is available to authorized users.

Comparative analysis of the gut microbiota of hornbill and toucan in captivity

Gut microbiota plays an important role in animals and are considered microbial organs. Hornbill and toucan are birds of the same ecotypes with high appreciative value. In this study, we characterized and compared the gut microbiota of toco toucan (Ramphastos toco), great hornbill (Buceros bicornis) and wreathed hornbill (Rhyticeros undulatus) using 16S rRNA high-throughput sequencing technology, and further discussed the influence of host bird genetics on its gut microbiota. We identified 10,847 operational taxonomic units (OTUs) from the hyper-variable V4-V5 region, representing 14 phyla that were dominated by the Firmicutes, Proteobacteria, Cyanobacteria, Fusobacteria, Actinobacteria, and Bacteroidetes. Alpha diversity indices showed no significant difference among the three species (p > 0.1). However, great hornbill and toco toucan shared a high number of OTUs. Principal component analysis also revealed highly similar gut microbiotas between the two distant species. Therefore, environmental factors might dominate over host genetics in shaping the gut microbiotas of hornbill and toucan. Our study would contribute in elucidating adaptation of the hornbill and toucan to environmental change.

Network-guided genomic and metagenomic analysis of the faecal microbiota of the critically endangered kakapo

The kakapo is a critically endangered, herbivorous parrot endemic to New Zealand. The kakapo hindgut hosts a dense microbial community of low taxonomic diversity, typically dominated by Escherichia fergusonii, and has proven to be a remarkably stable ecosystem, displaying little variation in core membership over years of study. To elucidate mechanisms underlying this robustness, we performed 16S rRNA gene-based co-occurrence network analysis to identify potential interactions between E. fergusonii and the wider bacterial community. Genomic and metagenomic sequencing were employed to facilitate interpretation of potential interactions observed in the network. E. fergusonii maintained very few correlations with other members of the microbiota, and isolates possessed genes for the generation of energy from a wide range of carbohydrate sources, including plant fibres such as cellulose. We surmise that this dominant microorganism is abundant not due to ecological interaction with other members of the microbiota, but its ability to metabolise a wide range of nutrients in the gut. This research represents the first concerted effort to understand the functional roles of the kakapo microbiota, and leverages metagenomic data to contextualise co-occurrence patterns. By combining these two techniques we provide a means for studying the diversity-stability hypothesis in the context of bacterial ecosystems.

The cultivable autochthonous microbiota of the critically endangered Northern bald ibis (Geronticus eremita)

The critically endangered Northern bald ibis (Geronticus eremita) is a migratory bird that became extinct in Europe centuries ago. Since 2014, the Northern bald ibis is subject to an intensive rehabilitation and conservation regime aiming to reintroduce the bird in its original distribution range in Central Europe and concurrently to maintain bird health and increase population size. Hitherto, virtually nothing is known about the microbial communities associated with the ibis species; an information pivotal for the veterinary management of these birds. Hence, the present study was conducted to provide a baseline description of the cultivable microbiota residing in the Northern bald ibis. Samples derived from the choana, trachea, crop and cloaca were examined employing a culturomic approach in order to identify microbes at each sampling site and to compare their frequency among age classes, seasonal appearances and rearing types. In total, 94 microbial species including 14 potentially new bacterial taxa were cultivated from the Northern bald ibis with 36, 58 and 59 bacterial species isolated from the choana, crop and cloaca, respectively. The microbiota of the Northern bald ibis was dominated by members of the phylum Firmicutes, followed by Proteobacteria, Actinobacteria, Bacteroidetes and Fusobacteria, altogether phylotypes commonly observed within avian gut environments. Differences in relative abundances of various microbial taxa were evident among sample types indicating mucosa-specific colonisation properties and tissue tropism. Besides, results of the present study indicate that the composition of microbiota was also affected by age, season (environment) and rearing type. While the prevalence of traditional pathogenic microbial species was extremely low, several opportunists including Clostridium perfringens toxotype A were frequently present in samples indicating that the Northern bald ibis may represent an important animal reservoir for these pathogens. In summary, the presented study provides a first inventory of the cultivable microbiota residing in the critically endangered Northern bald ibis and represents a first step in a wider investigation of the ibis microbiome with the ultimate goal to contribute to the management and survival of this critically endangered bird.

Host Age Affects the Development of Southern Catfish Gut Bacterial Community Divergent From That in the Food and Rearing Water

Host development influences gut microbial assemblies that may be confounded partly by dietary shifts and the changing environmental microbiota during ontogenesis. However, little is known about microbial colonization by excluding dietary effects and compositional differences in microbiota between the gut and environment at different ontogenetic stages. Herein, a developmental gut microbial experiment under controlled laboratory conditions was conducted with carnivorous southern catfish Silurus meridionalis fed on an identical prey with commensal and abundant microbiota. In this study, we provided a long-term analysis of gut microbiota associated with host age at 8, 18, 35, 65, and 125 day post-fertilization (dpf) and explored microbial relationships among host, food and water environment at 8, 35, and 125 dpf. The results showed that gut microbial diversity in southern catfish tended to increase linearly as host aged. Gut microbiota underwent significant temporal shifts despite similar microbial communities in food and rearing water during the host development and dramatically differed from the environmental microbiota. At the compositional abundance, Tenericutes and Fusobacteria were enriched in the gut and markedly varied with host age, whereas Spirochaetes and Bacteroidetes detected were persistently the most abundant phyla in food and water, respectively. In addition to alterations in individual microbial taxa, the individual differences in gut microbiota were at a lower level at the early stages than at the late stages and in which gut microbiota reached a stable status, suggesting the course of microbial successions. These results indicate that host development fundamentally shapes a key transition in microbial community structure, which is independent of dietary effects. In addition, the dominant taxa residing in the gut do not share their niche habitats with the abundant microbiota in the surrounding environment. It's inferred that complex gut microbiota could not be simple reflections of environmental microbiota. The knowledge enhances the understanding of gut microbial establishment in the developing fish and provides a useful resource for such studies of fish- or egg-associated microbiota in aquaculture.

The Low-Diversity Fecal Microbiota of the Critically Endangered Kākāpō Is Robust to Anthropogenic Dietary and Geographic Influences

The critically endangered kākāpō, an herbivorous parrot endemic to New Zealand, is subject to intensive management to increase its population size. Key aspects of the management program include supplementary feeding and translocation of kākāpō between different predator-free islands to optimize the genetic composition of the breeding populations. While these practices have helped boost the kākāpō population, their impact on the kākāpō fecal microbiota is uncertain. Previous studies have found that the kākāpō possesses a low-diversity fecal microbiota, typically dominated by Escherichia/Shigella spp. However, the question of whether the low diversity of the kākāpō fecal microbiota is an inadvertent consequence of human interventions has yet to be investigated. To that end, we used high-throughput Illumina sequencing of 16S rRNA gene amplicons obtained from fecal material of 63 kākāpō representing different diets, islands, and ages. Remarkably, neither supplementary feeding nor geographic location were associated with significant differences in the overall fecal microbial community structures of adult kākāpō, suggesting that the kākāpō's low-diversity fecal microbiota is both inherent to this species and robust to these external influences.

Temporal Stability and the Effect of Transgenerational Transfer on Fecal Microbiota Structure in a Long Distance Migratory Bird

Animal bodies are inhabited by a taxonomically and functionally diverse community of symbiotic and commensal microorganisms. From an ecological and evolutionary perspective, inter-individual variation in host-associated microbiota contributes to physiological and immune system variation. As such, host-associated microbiota may be considered an integral part of the host’s phenotype, serving as a substrate for natural selection. This assumes that host-associated microbiota exhibits high temporal stability, however, and that its composition is shaped by trans-generational transfer or heritable host-associated microbiota modulators encoded by the host genome. Although this concept is widely accepted, its crucial assumptions have rarely been tested in wild vertebrate populations. We performed 16S rRNA metabarcoding on an extensive set of fecal microbiota (FM) samples from an insectivorous, long-distance migratory bird, the barn swallow (Hirundo rustica). Our data revealed clear differences in FM among juveniles and adults as regards taxonomic and functional composition, diversity and co-occurrence network complexity. Multiple FM samples from the same juvenile or adult collected within single breeding seasons exhibited higher similarity than expected by chance, as did adult FM samples over two consecutive years. Despite low effect sizes for FM stability over time at the community level, we identified an adult FM subset with relative abundances exhibiting significant temporal consistency, possibly inducing long-term effects on the host phenotype. Our data also indicate a slight maternal (but not paternal) effect on FM composition in social offspring, though this is unlikely to persist into adulthood. We discuss our findings in the context of both evolution and ecology of microbiota vs. host interactions and barn swallow biology.

Effects of captivity and artificial breeding on microbiota in feces of the red-crowned crane (Grus japonensis)

Reintroduction of the threatened red-crowned crane has been unsuccessful. Although gut microbiota correlates with host health, there is little information on gut microbiota of cranes under different conservation strategies. The study examined effects of captivity, artificial breeding and life stage on gut microbiota of red-crown cranes. The gut microbiotas of wild, captive adolescent, captive adult, artificially bred adolescent and artificially bred adult cranes were characterized by next-generation sequencing of 16S rRNA gene amplicons. The gut microbiotas were dominated by three phyla: Firmicutes (62.9%), Proteobacteria (29.9%) and Fusobacteria (9.6%). Bacilli dominated the 'core' community consisting of 198 operational taxonomic units (OTUs). Both captivity and artificial breeding influenced the structures and diversities microbiota of the gut. Especially, wild cranes had distinct compositions of gut microbiota from captive and artificially bred cranes. The greatest alpha diversity was found in captive cranes, while wild cranes had the least. According to the results of ordination analysis, influences of captivity and artificial breeding were greater than that of life stage. Overall, captivity and artificial breeding influenced the gut microbiota, potentially due to changes in diet, vaccination, antibiotics and living conditions. Metagenomics can serve as a supplementary non-invasive screening tool for disease control.

Vertebrate bacterial gut diversity: size also matters

Background

One of the central issues in microbial ecology is to understand the parameters that drive diversity. Among these parameters, size has often been considered to be the main driver in many different ecosystems. Surprisingly, the influence of size on gut microbial diversity has not yet been investigated, and so far in studies reported in the literature only the influences of age, diet, phylogeny and digestive tract structures have been considered. This study explicitly challenges the underexplored relationship connecting gut volume and bacterial diversity.

Results

The bacterial diversity of 189 faeces produced by 71 vertebrate species covering a body mass range of 5.6 log. The animals comprised mammals, birds and reptiles. The diversity was evaluated based on the Simpson Diversity Index extracted from 16S rDNA gene fingerprinting patterns. Diversity presented an increase along with animal body mass following a power law with a slope z of 0.338 ± 0.027, whatever the age, phylogeny, diet or digestive tract structure.

Conclusions

The results presented here suggest that gut volume cannot be neglected as a major driver of gut microbial diversity. The characteristics of the gut microbiota follow general principles of biogeography that arise in many ecological systems.

Electronic supplementary material

The online version of this article (doi:10.1186/s12898-016-0071-2) contains supplementary material, which is available to authorized users.

High-throughput sequencing reveals the core gut microbiome of Bar-headed goose (Anser indicus) in different wintering areas in Tibet

Elucidating the spatial dynamic and core gut microbiome related to wild bar‐headed goose is of crucial importance for probiotics development that may meet the demands of bar‐headed goose artificial breeding industries and accelerate the domestication of this species. However, the core microbial communities in the wild bar‐headed geese remain totally unknown. Here, for the first time, we present a comprehensive survey of bar‐headed geese gut microbial communities by Illumina high‐throughput sequencing technology using nine individuals from three distinct wintering locations in Tibet. A total of 236,676 sequences were analyzed, and 607 OTUs were identified. We show that the gut microbial communities of bar‐headed geese have representatives of 14 phyla and are dominated by Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. The additive abundance of these four most dominant phyla was above 96% across all the samples. At the genus level, the sequences represented 150 genera. A set of 19 genera were present in all samples and considered as core gut microbiome. The top seven most abundant core genera were distributed in that four dominant phyla. Among them, four genera (Lactococcus, Bacillus, Solibacillus, and Streptococcus) belonged to Firmicutes, while for other three phyla, each containing one genus, such as Proteobacteria (genus Pseudomonas), Actinobacteria (genus Arthrobacter), and Bacteroidetes (genus Bacteroides). This broad survey represents the most in‐depth assessment, to date, of the gut microbes that associated with bar‐headed geese. These data create a baseline for future bar‐headed goose microbiology research, and make an original contribution to probiotics development for bar‐headed goose artificial breeding industries.

Exploring the avian gut microbiota: current trends and future directions

Birds represent a diverse and evolutionarily successful lineage, occupying a wide range of niches throughout the world. Like all vertebrates, avians harbor diverse communities of microorganisms within their guts, which collectively fulfill crucial roles in providing the host with nutrition and protection from pathogens. Across the field of avian microbiology knowledge is extremely uneven, with several species accounting for an overwhelming majority of all microbiological investigations. These include agriculturally important birds, such as chickens and turkeys, as well as birds of evolutionary or conservation interest. In our previous study we attempted the first meta-analysis of the avian gut microbiota, using 16S rRNA gene sequences obtained from a range of publicly available data sets. We have now extended our analysis to explore the microbiology of several key species in detail, to consider the avian microbiota within the context of what is known about other vertebrates, and to identify key areas of interest in avian microbiology for future study.