Nerea M Molina1, Julio Plaza-Díaz2, Ramiro Vilchez-Vargas3, Alberto Sola-Leyva1, Eva Vargas4, Raquel Mendoza-Tesarik5, Maribel Galán-Lázaro5, Nicolás Mendoza-Ladrón de Guevara6, Jan Tesarik5, Signe Altmäe7. 1. University of Granada, Department of Biochemistry and Molecular Biology I, Faculty of Sciences, Granada 18071, Spain; Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain. 2. Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain; University of Granada, Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, Granada 18071, Spain; Institute of Nutrition and Food Technology (INYTA), 'José Mataix Verdú' Biomedical Research Centre (CIBM), University of Granada, Granada 18016, Spain; Children's Hospital of Eastern Ontario Research Institute, Ottawa ON K1H 8L1, Canada. 3. Department of Gastroenterology, Hepatology, and Infectious Diseases, Otto von Guericke University Hospital Magdeburg, Magdeburg 39120, Germany. 4. Systems Biology Unit, Department of Experimental Biology, Faculty of Experimental Sciences, University of Jaen, Jaen 23071, Spain. 5. MARGen Clinic, Molecular Assisted Reproduction and Genetics, Granada 18006, Spain. 6. University of Granada, Department of Obstetrics and Gynecology, Faculty of Medicine, Granada 18071, Spain. 7. University of Granada, Department of Biochemistry and Molecular Biology I, Faculty of Sciences, Granada 18071, Spain; Instituto de Investigación Biosanitaria ibs.GRANADA, Granada 18014, Spain; Competence Centre on Health Technologies, Tartu 50410, Estonia. Electronic address: signealtmae@ugr.es.
Abstract
RESEARCH QUESTION: The semen harbours a diverse range of microorganisms. The origin of the seminal microbes, however, has not yet been established. Do testicular spermatozoa harbour microbes and could they potentially contribute to the seminal microbiome composition? DESIGN: The study included 24 samples, comprising a total of 307 testicular maturing spermatozoa. A high-throughput sequencing method targeting V3 and V4 regions of 16S rRNA gene was applied. A series of negative controls together with stringent in-silico decontamination methods were analysed. RESULTS: Between 50 and 70% of all the detected bacterial reads accounted for contamination in the testicular sperm samples. After stringent decontamination, Blautia (P = 0.04), Cellulosibacter (P = 0.02), Clostridium XIVa (P = 0.01), Clostridium XIVb (P = 0.04), Clostridium XVIII (P = 0.02), Collinsella (P = 0.005), Prevotella (P = 0.04), Prolixibacter (P = 0.02), Robinsoniella (P = 0.04), and Wandonia (P = 0.04) genera demonstrated statistically significant abundance among immature spermatozoa. CONCLUSIONS: Our results indicate that the human testicle harbours potential bacterial signature, though in a low-biomass, and could contribute to the seminal microbiome composition. Further, applying stringent decontamination methods is crucial for analysing microbiome in low-biomass site.
RESEARCH QUESTION: The semen harbours a diverse range of microorganisms. The origin of the seminal microbes, however, has not yet been established. Do testicular spermatozoa harbour microbes and could they potentially contribute to the seminal microbiome composition? DESIGN: The study included 24 samples, comprising a total of 307 testicular maturing spermatozoa. A high-throughput sequencing method targeting V3 and V4 regions of 16S rRNA gene was applied. A series of negative controls together with stringent in-silico decontamination methods were analysed. RESULTS: Between 50 and 70% of all the detected bacterial reads accounted for contamination in the testicular sperm samples. After stringent decontamination, Blautia (P = 0.04), Cellulosibacter (P = 0.02), Clostridium XIVa (P = 0.01), Clostridium XIVb (P = 0.04), Clostridium XVIII (P = 0.02), Collinsella (P = 0.005), Prevotella (P = 0.04), Prolixibacter (P = 0.02), Robinsoniella (P = 0.04), and Wandonia (P = 0.04) genera demonstrated statistically significant abundance among immature spermatozoa. CONCLUSIONS: Our results indicate that the human testicle harbours potential bacterial signature, though in a low-biomass, and could contribute to the seminal microbiome composition. Further, applying stringent decontamination methods is crucial for analysing microbiome in low-biomass site.