Functional analysis of Rickettsia monacensis strain humboldt folA dihydrofolate reductase gene via complementation assay

The impact of bloodmeal and geographic region on the richness, diversity, and function of internal microbial community in Haemaphysalis qinghaiensis from the Qinghai province, China

Background

Ticks are ectoparasites that feed on blood and pose a threat to both the livestock industry and public health due to their ability to transmit pathogens through biting. However, the impact of factors such as bloodmeal and geographic regions on the bacterial microbiota of Haemaphysalis qinghaiensis remains poorly understood.

Methods

In this study, we used the v3-v4 region of the 16S rRNA gene to sequence the microbiota of Haemaphysalis qinghaiensis from eight groups (HY_M, YS_M, XH_M, LD_M, BM_M, LD_F_F, LD_F, and BM_F_F) in Qinghai Province.

Results

Significant differences in bacterial richness were observed between LD_F_F, BM_F_F, and LD_F (P < 0.01), and among the five groups (HY_M, YS_M, XH_M, BM_M, and LD_M) (P < 0.05). The bacterial diversity also differed significantly between LD_F_F, LD_F, and BM_F_F (P < 0.01), as well as among the five groups (HY_M, YS_M, XH_M, LD_M, and BM_M) (P < 0.01). The group with the highest number of operational taxonomic units (OTUs) was LD_F, accounting for 23.93 % (419/1751), while BM_F_F accounted for at least 0.80 % (14/1751). At the phylum level, Firmicutes was the most abundant, with relative abundance ranging from 7.44 % to 96.62 %. At the genus level, Staphylococcus had the highest abundance, ranging from 1.67 % to 97.53 %. The endosymbiotic bacteria Coxiella and Rickettsia were predominantly enriched in LD_F_F. Additionally, the 16S gene of Coxiella showed the highest identity of 99.07 % with Coxiella sp. isolated from Xinxiang hl9 (MG9066 71.1), while the 16S gene of Rickettsia had 100 % identity with Candidatus Rickettsia hongyuanensis strains (OK 662395.1). Functional predictions for the prokaryotic microbial community indicated that the main functional categories were Metabolic, Genetic information processing, and Environmental information processing across the eight groups.

Conclusion

This study provides a theoretical basis for the prevention and treatment of tick-borne diseases, which is of great significance for public health.

Effect of folA gene in human breast milk-derived Limosilactobacillus reuteri on its folate biosynthesis

Introduction

Folate supplementation is crucial for the human body, and the chemically synthesized folic acid might have undesirable side effects. The use of molecular breeding methods to modify the genes related to the biosynthesis of folate by probiotics to increase folate production is currently a focus of research.

Methods

In this study, the folate-producing strain of Limosilactobacillus reuteri B1-28 was isolated from human breast milk, and the difference between B1-28 and folA gene deletion strain ΔFolA was investigated by phenotyping, in vitro probiotic evaluation, metabolism and transcriptome analysis.

Results

The results showed that the folate producted by the ΔFolA was 2-3 folds that of the B1-28. Scanning electron microscope showed that ΔFolA had rougher surface, and the acid-producing capacity (p = 0.0008) and adhesion properties (p = 0.0096) were significantly enhanced than B1-28. Transcriptomic analysis revealed that differentially expressed genes were mainly involved in three pathways, among which the biosynthesis of ribosome and aminoacyl-tRNA occurred in the key metabolic pathways. Metabolomics analysis showed that folA affected 5 metabolic pathways, involving 89 different metabolites.

Discussion

In conclusion, the editing of a key gene of folA in folate biosynthesis pathway provides a feasible pathway to improve folate biosynthesis in breast milk-derived probiotics.

Tick symbiosis

As obligate blood-feeders, ticks serve as vectors for a variety of pathogens that pose threats on both human and livestock health. The microbiota that ticks harbor play important roles in influencing tick nutrition, development, reproduction, and vector. These microbes also affect the capacity of ticks to transmit pathogens (vector competence). Therefore, comprehending the functions of tick microbiota will help in developing novel and effective tick control strategies. Here, we summarize the effects of main tick symbiotic bacteria on tick physiology and vector competency.