3.1. Microbial community annotation of different NHPs.
In all primate species, bacterial overwhelmingly dominated, contributing a greater degree of phylogenetic diversity compared to archaea, eukaryotes, and viruses (Figure S2). At the phylum level, all samples were allocated to 17 distinct phyla, encompassing 14 for NHPs and 12 for humans. Striking similarities emerged between NHPs and humans in terms of their bacterial composition patterns. Notably, within Homo sapiens, T. leucocephalus, Hylobatidae, Papio, M. multta, T. francoisi, N. pygmaeus, T. cristatus, and N. coucang, the predominant phylum was Firmicutes (51%, 47%, 95%, 69%, 71%, 53%, 77%, 81% and 65%, respectively), while in Lemur catta, the most abundant phylum was Spirochaetes (58.0%). Broadly, Firmicutes, Bacteroidetes, Euryarchaeota, and Proteobacteria constituted the four prevailing phyla across all species, cumulatively accounting for approximately 85.83% of the total bacterial community (Fig. 1A).
At the genus level, 228 genera were identified across all samples, showcasing diverse representative genera in each species. A substantial proportion of the Subdoligranulum genus were identified in Presbytis (T. leucocephalus, T. francoisi, T. cristatus) (56.53%, 31.03% and 42.36 respectively), while the predominant genus Megamonas was observed in Nycticebus (N. pygmaeus, N. coucang) (47.93% and 27.14% respectively). Notably, humans exhibited a uniquely enriched genus, Bacteroides (22%), whereas Papio harbored the most abundant genus Megasphaera (17%). In Hylobatidae, the leading genus was Faecalibacterium (33%), whereas in Lemur catta, the genus Treponema was particularly enriched (38%) (Fig. 1B). Furthermore, a total of 85 species-specific genera were identified, each characterized by relatively lower abundances. For instance, Papio had 20 such genera, T. leucocephalus had 19, Homo sapiens had 14, N. coucang had 12, Lemur catta had 9, N. pygmaeus had 4, T. cristatus had 3, M. multta had 2, and both Hylobatidae and T. francoisi had 1 each. Additionally, 18 genera were detected as shared across all species, including Subdoligranulum, Bacteroides, Phascolarctobacterium and Methanobrevibacter, which were included in the top 50 most abundant genera (Figure S3).
3.2. Distinct gut bacterial communities across NHPs.
The phylogenetic relationships among the ten primate species are depicted in Fig. 2A. Utilizing a genus-level relative abundance profile, a principal coordination analysis (PCoA) plot elucidated that axis 1 (PCoA1) accounted for 26.77% of the variance, while axis 2 (PCoA2) accounted for 16.27%. Homo sapiens, N. coucang and N. pygmaeus samples exhibited clustering tendencies, distinct from the remaining samples (Fig. 2B). Intriguingly, species sharing genetic host backgrounds demonstrated resemblant gut microbial structures, diverging from prior findings[41]. Employing LEfSe, we compared the relative abundance of gut bacteria between humans and seven other NHPs species (Figure S4). Specifically, 2 phyla (Actinobacteria and Bacteroidetes), 2 classes (Actinobacteria and Bacteroidia), 2 orders (Bacteroidales and Bifidobacteriales), 4 families (Bacteroidaceae, Bifidobacteriaceae, Eubacteriaceae and Rikenellaceae), 7 genera (Alistipes, Bacteroides, Bifidobacterium, Blautia, Eubacterium, Faecalibacterium and Ruminococcus), and 10 species (Ruminococcus_bromii, Roseburia_inulinivorans, Roseburia_intestinalis, Faecalibacterium_prausnitzii, Eubacterium_rectale, Eubacterium_eligens, Bifidobacterium_longum, Bacteroides_vulgatus, Bacteroides_stercoris) exhibited significantly higher abundance in homo sapiens (P < 0.01 and LDA > 4) (Fig. 2D).
In total, 107 opportunistic pathogens were detected across all species through comparison with a previously published pathogen list[46]. Among these, 10 pathogens were shared across all ten primates (Fig. 2C). Escherichia coli and Bacteroides eggerthii prevailed most frequently, with Homo sapiens (59), N. coucang (55) and N. pygmaeus (45) hosting the broadest spectrum of pathogens. Clinically pertinent pathogens were identified in NHPs, including Clostridium perfringens, Klebsiella pneumoniae, and Clostridium difficile, which were also found in the migratory birds.
3.3. The ARGs and resistant phenotype among NHPs.
A total of 18 distinct ARG types were identified across various primate populations. Tetracycline resistance genes comprised the largest proportion at 40% of all detected ARGs, followed by MLS resistance genes (21%), beta-lactam resistance genes (11%), and multidrug resistance genes (8%) ((Figure S5 and Figure S6). The ARGs for Tetracycline, bacitracin, MLS, multidrug, and vancomycin were consistently detected in all samples (Fig. 3A). The total abundance of ARGs in the different species exhibited the following ranges: Homo sapiens (0.384–1.597), T. leucocephalus (9.587×10− 6–4.480×10− 1), M. multta (1.023×10− 5–1.040×10− 1), N. coucang (1.438×10− 5–3.24×10− 1), N. pygmaeus (1.007×10− 5–2.890×10− 1), Lemur catta (6.671×10− 6–1.250×10− 1), T. francoisi (1.004×10− 5–2.670×10− 1), T. cristatus (1.057×10− 5–1.880×10− 1), Hylobatidae (2.018×10− 5–2.410×10− 1), and Papio (4.513×10− 5–2.20×10− 1) (Fig. 3C).
More specifically, within M. multta, the dominant resistance genes were tetracycline, MLS, vancomycin, and aminoglycoside, accounting for 65.71%, 9.00%, 5.23%, and 4.61% respectively (Figure S7 A). For T. leucocephalus, the foremost resistance genes were multidrug, tetracycline, MLS, and bacitracin, constituting 46.47%, 16.26%, 9.96%, and 8.05%, respectively (Figure S6 B). In captive N. coucang and N. pygmaeus, 16 ARGs were observed, with prominent types being tetracycline (49.13%, 47.39%), MLS (18.07%, 13.96%), and beta-lactam (9.07%, 7.02%) (Fig. 7C, D). Tetracycline, aminoglycoside, MLS, and vancomycin accounted for 42.20%, 12.01%, 6.69%, and 10.82% respectively in T. francoisi, and 62.90%, 12.15%, 6.95%, and 5.03% respectively in T. cristatus (Figure S6 G, H). Among Hylobatidae and Papio, which exhibited 18 ARGs, tetracycline (46.19%), beta-lactam (32.02%), MLS (5.98%), and bacitracin (5.03%) were predominant in Hylobatidae (Figure S6 F). In Papio, tetracycline (39.77%), multidrug (20.41%), MLS (11.95%), and beta-lactam (5.92%) dominated (Figure S6 I, J). For Lemur catta, 18 ARGs were evident, with tetracycline (36.51%), beta-lactam (24.3%), MLS (18.55%), and chloramphenicol (6.64%) as primary resistance genes (Figure S7 E). Notably, all ARGs annotated in human were also present in the NHPs (Figure S7 K).
A total of 580 ARGs were identified across all samples, with relative abundances spanning from 3.01x10− 6 (TEM-201) to 10.07 (tetQ). The heatmap showcased the top 100 most abundant ARGs, comprising 34 classified as multidrug resistance, 16 as tetracycline, 11 as MLS, and 8 as aminoglycoside (Fig. 2B). vanR and macB were universally shared across all samples, indicating their ubiquitous presence among primates. Tetracycline-related ARGs, including tet35, tet36, tet37, tet39, tet40, tet44, tetA, tetL, tetM, tetO, tetP, tetQ, tetracycline_resistance_protein, tetW, tetX1, and tetX2, exhibited high abundances in captive primates. Furthermore, a total 93 ARGs were shared among the ten primate species, with Papio harboring the most diverse ARGs (355) (Figure S8).
3.4 Comparative analysis of resistome between NPHs and humans
Previous studies have underscored the close resemblance between the gut microbiomes of NHPs and humans, suggesting the potential utility of NHPs in biomedical research as model[38, 47]. Building on this premise, we conducted a comparison of antibiotic resistome composition and diversity indices between nine NHPs and humans adhering to a non-westernized diet. Our analysis revealed the existence of 16 ARGs shared between both humans and NHPs. Moreover, rifamycin resistance genes were exclusively identified in NHPs, albeit at a limited frequency. Among these genes, tetracycline stood out as the most prevalent and dominant ARGs in metagenomic resistome profiles of both humans and NHPs, followed by MLS, beta-lactam, and multidrug (Fig. 4A).
Diversity index analysis demonstrated that human exhibited relatively higher Simpson, Shannon, and Chao1 indices, compared to NHPs. Notably, captive Papio displayed the highest diversity indexes. PCA plots based on ARGs relative abundance indicated that nearly all NHPs samples (particularly those from T. francoisi, T. cristatus, N. pygmaeus, and M. mulatta) were closely situated to human samples (Fig. 4D, Figure S9 B-D, F). However, some T. leucocephalus and Lemur catta samples diverged from human samples in the PCA plot (Figure S10 A and E). A considerable abundance of ARGs was identified in samples from the Wuzhou Langur Breeding and Research Center and Nanning Zoon’s T. francoisi (Figure S9). consequently, it can be inferred that lifestyles and geography exert an influence on similarities and abundance of ARGs among the NHPs.
Thus, NHPs resistomes represent a potentially crucial reservoir for studying antibiotic resistance within human gut microbiota. This warrants attention as captive NHPs frequently interact with humans, raising concerns for potential public health implications. Furthermore, it is noteworthy that both wild T. leucocephalus and M. mulatta harbor numerous ARGs that align with those found in human beings.
3.5. Co-occurrence network analysis of ARGs in NHPs.
Procrustes analysis was employed to elucidate correlations between ARG subtypes and bacteria taxa at the genus level. Deviation square M2 yielded a value of 0.9374, with a corresponding P value 0.001 for ARGs and ARGs (Fig. 5A). Additionally, the deviation square M2 for ARGs and microbiota amounted to 0.9708, with P value of 0.001 (Fig. 5B).
To unravel the co-occurrence patterns of ARGs within the ten NHPs, a co-occurrence network was constructed based on robust and statistically significant correlations among different NPHs found in individuals (|ρ|>0.6, P < 0.01). The co-occurrence network diagrams for ARGs contained 12 antibiotic types encompassing 79 resistance genes (Fig. 5C). Positive correlations emerged among similar ARGs indicative of the shared selective pressure imposed by specific antibiotics. For example, tetracycline ARGs tetO, tetM, tet32, tetX2, tetX and tetX3 exhibited such correlations. Similar patterns were observed for tetracycline-related ARGs vanR and vanS. Only one negative correlation was observed between different ARGs, such as bacA (bacitracin ARG) and vatB (MLS ARG). This could be attributed to competition among host bacteria or inhibition-related dynamics[48].
Illustrated in Fig. 5D, the network comprised 61 nodes and 84 edges (with a modularity index of 0.602), including Bifidobacterium, Clostridium, Subdoligranulum, and Ruminococcaceae_noname. Furthermore, 38 species levels were linked to 10 resistance gene types, encompassing tetracycline, vancomycin, aminoglycoside, bacitracin, multidrug, MLS, beta-lactamase, beta-lactam, trimethoprim and chloramphenicol. Notably, Treponema exhibited a positive correlation with vatB (MLS ARG), indicating that its potential role as a host for ARGs. Concurrently, certain species displayed negative correlation with ARGs, exemplified by the Spirochaetes phylum, Treponema, and bacA (bacitracin ARG). Thus, intricate interaction between various ARGs and microbes were evident, underscoring the intimate connection between NHP gut microbes and ARGs. Besides, based on these results we can tract the hosts for specific ARG subtypes[49].