Brain abscess caused by multidrug-resistant Acinetobacter baumannii

Influence of dietary supplementation with Bacillus velezensis on intestinal microbial diversity of mice

Yaks are an aboriginal breed of the Qinghai-Tibet plateau (3000 m), which are highly adaptable to cold and hypoxic environments. It is noticed that hypoxia and hypothermia can induce changes in intestinal microbial structure in animals. Increasing evidences suggested that probiotics supplementation can improve the balance of gut microbiota of animals. However, so far, very few studies have emphasized on the probiotics isolated from yaks in the Qinghai-Tibet Plateau. Therefore, a potential probiotic strain Bacillus velezensis was isolated from yaks. In the present study, a total of 18 Kunming mice (15-18 g) were equally distributed into two groups; control and probiotic treated groups (1 × 10⁹ CFU/day). During the experimental period, all the mice from both groups were given standard normal diet ad libitum. At the end of the experiment, mice were euthanized and the intestines (duodenum, jejunum, ileum, and cecum) were removed for high-throughput sequencing. The results demonstrated that Bacillus velezensis supplementation showed beneficial effects on the gut microbiota of mice. Specifically, Bacillus velezensis supplementation increased the population of Lactobacillus and Ruminococcus in the duodenum, and Candidatus Arthromitus in the jejunum. Additionally, Acinetobacter in the duodenum and Helicobacter in the cecum were decreased after feeding Bacillus velezensis. Altogether, these findings suggested that Bacillus velezensis isolated from Tibetan yaks can improve gut microbiota of mice.

The impact of Bacillus subtilis 18 isolated from Tibetan yaks on growth performance and gut microbial community in mice

The purpose of this study was to evaluate the effects of Bacillus subtilis 18 (BS-18) isolated from free-ranging Tibetan yaks in high altitude regions of Tibet (3600 m) on growth performance and gut microbial community in mice. In this study, mice (15-day-old) were used as an animal model and raised under standard conditions. A total of 20 KM mice were divided equally into two groups: control group (feed and drink freely), experimental group (feed and drink freely + 1 × 10⁹ CFU/day BS-18). The intestines (duodenum, jejunum, ileum, cecum) and organs (liver, spleen, kidney) were collected from all the mice at day 18 for high throughput sequencing and HE staining. During the whole experiment, the mice treated by BS-18 displayed no abnormal behavior or macroscopic lesions on dissection. Meanwhile, there were no pathological changes observed using HE staining compared with the control group. The results show that BS-18 isolated from Tibetan yaks was safe and could increase average daily gain (ADG) and reduce feed conversion ratio (FCR). Furthermore, supplementation with BS-18 could improve the mucosal morphology and the ratio of villi to crypt cells (P < 0.05 or P < 0.01). The high-throughput sequencing results showed that the abundance and diversity of duodenum and jejunum in the experimental group were higher than control group. Lactobacillus in experimental group had higher abundance than control group. In addition, the quantity of Candidatus arthromitu was increased after BS-18 intake, which is associated with immune system activity. Acinetobacter induced brain abscess and bronchopneumonia were reduced in the experimental group. In conclusion, this study demonstrated that BS-18 isolated from Tibetan yaks was safe, beneficial and had the potential to serve as a probiotic.