The domestic Bactrian camels were treated as one of the principal means of locomotion between the eastern and western cultures in history. However, whether they originated from East Asia or Central Asia remains elusive. To address this question, we perform whole-genome sequencing of 128 camels across Asia. The extant wild and domestic Bactrian camels show remarkable genetic divergence, as they were split from dromedaries. The wild Bactrian camels also contribute little to the ancestry of domestic ones, although they share close habitat in East Asia. Interestingly, among the domestic Bactrian camels, those from Iran exhibit the largest genetic distance and the earliest split from all others in the phylogeny, despite evident admixture between domestic Bactrian camels and dromedaries living in Central Asia. Taken together, our study support the Central Asian origin of domestic Bactrian camels, which were then immigrated eastward to Mongolia where native wild Bactrian camels inhabit.

The bacterial community plays important roles in the gastrointestinal tracts (GITs) of animals. However, our understanding of the microbial communities in the GIT of Bactrian camels remains limited. Here, we describe the bacterial communities from eight different GIT segments (rumen, reticulum, abomasum, duodenum, ileum, jejunum, caecum, colon) and faeces determined from 11 Bactrian camels using 16S rRNA gene amplicon sequencing. Twenty-seven bacterial phyla were found in the GIT, with Firmicutes, Verrucomicrobia and Bacteroidetes predominating. However, there were significant differences in microbial community composition between segments of the GIT. In particular, a greater proportion of Akkermansia and Unclassified Ruminococcaceae were found in the large intestine and faecal samples, while more Unclassified Clostridiales and Unclassified Bacteroidales were present in the in forestomach and small intestine. Comparative analysis of the microbiota from different GIT segments revealed that the microbial profile in the large intestine was like that in faeces. We also predicted the metagenomic profiles for the different GIT regions. In forestomach, there was enrichment associated with replication and repair and amino acid metabolism, while carbohydrate metabolism was enriched in the large intestine and faeces. These results provide profound insights into the GIT microbiota of Bactrian camels.

Camel milk is a nutritionally rich food that shows anti-inflammatory, immune regulation, and gut microbiota maintenance properties. However, the relationship between camel milk and the intestinal microbiota during colitis is unclear. Herein, we evaluated the protective effect of camel milk in mice with colitis induced using dextran sodium sulfate. Our results showed that camel milk can prevent body weight loss and colon shortening, reduce the disease activity index, and attenuate colon tissue damage. Additionally, camel milk could reduce the overexpression of inflammatory factors, inhibit the apoptosis of intestinal epithelial cells, and promote the expression of claudin-1, occludin, and zonula occludens-1 proteins. Moreover, camel milk effectively regulated intestinal microbiota in mice with colitis by increasing the gut microbiota diversity, increasing the abundance of beneficial bacteria (such as g_norank_f_Muribaculaceae, and Lachnospiraceae_NK4A136_group), and reducing the number of harmful bacteria (Bacteroides, Escherichia-Shigella). In addition, camel milk increased the levels of intestinal short-chain fatty acids. The results of the present study demonstrated that via regulating the intestinal microbiota, maintaining intestinal barrier function, and inhibiting proinflammatory cytokines, camel milk can ameliorate dextran sodium sulfate-induced colitis.

Antibacterial peptides were isolated and purified from whey proteins of camel milk (CaW) and cow milk (CoW) and their antimicrobial activities were studied. The whey proteins were hydrolyzed using trypsin, and the degree of hydrolysis was identified by gel electrophoresis. The whey hydrolysate (WH) was purified using ultrafiltration and Dextran gel chromatography to obtain small peptides with antibacterial activity. The effect of the antimicrobial peptides on the morphology of bacterial strains was investigated using transmission electron microscopy. Their amino acid composition and antimicrobial activities were then determined. Polypeptides CaWH-III (<3 kDa) and CoWH-III (<3 kDa) had the strongest antibacterial activity. Both Fr.A2 (CaWH-Ⅲ’s fraction 2) and Fr.B1 (CoWH-Ⅲ’s fraction 1) had antibacterial effects toward Escherichia coli and Staphylococcus aureus, with minimum antimicrobial mass concentrations of 65 mg/mL and 130 mg/mL for Fr.A2, and 130 mg/mL and 130 mg/mL for Fr.B1, respectively. The highly active antimicrobial peptides had high amounts of alkaline amino acids (28.13% in camel milk Fr.A2 and 25.07% in the cow milk Fr.B1) and hydrophobic amino acids. (51.29% in camel milk Fr.A2 and 57.69% in the cow milk Fr.B1). This results showed that hydrolysis of CaW and CoW using trypsin produced a variety of effective antimicrobial peptides against selected pathogens, and the antibacterial activity of camel milk whey was slightly higher than that of cow milk whey.

Camel milk is considered as an essential source of nutrition for desert people. However, few studies have investigated how geography affects Bactrian camel milk in Mongolia. In this study, we evaluated the differences in gross composition, fatty acid composition, and amino acid composition among Bactrian camel milk samples collected from 102 Bactrian camels in five different Mongolian regions. The proportion of long-chain fatty acids, out of total fatty acids, was high in all samples of Bactrian camel milk. The primary fatty acids detected in the samples were palmitic acid (23.99–30.72%), oleic acid (17.21–24.24%), and stearic acid (11.13–16.49%), while the dominant amino acids were leucine, lysine, valine, and aspartic acid. Cysteine was the least common amino acid detected in the Bactrian camel milk samples. Considerable differences in the fatty acid and amino acid compositions were observed among Bactrian camel milk from different regions of Mongolia. The findings suggest that geography strongly affects the composition of camel milk.

Morbidity and mortality as a result of liver disease are major problems around the world, especially from alcoholic liver disease (ALD), which is characterized by hepatic inflammation and intestinal microbial imbalance. In this study, we investigated the hepatoprotective effects of camel milk (CM) in a mouse model of acute ALD and the underlying mechanism at the gut microbiota and transcriptome level. Male Institute of Cancer Research mice (n = 24; Beijing Weitong Lihua Experimental Animal Technology Co. Ltd., China) were divided into 3 groups: normal diet (NC); normal diet, then ethanol (ET); and normal diet and camel milk (CM), then ethanol (ET+CM). Analysis of serum biochemical indexes and histology revealed a reduction in hepatic inflammation in the ET+CM group. Sequencing of 16S rRNA showed that CM modulated the microbial communities, with an increased proportion of Lactobacillus and reduced Bacteroides, Alistipes, and Rikenellaceae RC9 gut group. Comparative hepatic transcriptome analysis revealed 315 differentially expressed genes (DEG) in the ET+CM and ET groups (150 upregulated and 165 downregulated). Enrichment analysis revealed that CM downregulated the expression of inflammation-related (ILB and CXCL1) genes in the IL-17 and tumor necrosis factor (TNF-α) pathways. We conclude that CM modulates liver inflammation and alleviates the intestinal microbial disorder caused by acute alcohol injury, indicating the potential of dietary CM in protection against alcohol-induced liver injury.