We thank all men who generously donated testicular material for the purpose of this study. We also acknowledge the research support by Copan Italia S.p.A Inc., and Clearblue, SPD Swiss Precision Diagnostics GmbH. This study is part of a PhD Thesis conducted at the Official Doctoral Program in Biomedicine of the University of Granada, Spain. This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) and European Regional Development Fund (FEDER): grant numbers RYC-2016-21199 and ENDORE (SAF2017-87526-R); by FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento: MENDO (B-CTS-500-UGR18); by Junta de Andalucia: (PAIDI P20_00158) by the University of Granada, Plan Propio de Investigacion 2016, Excellence actions: Units of Excellence; Unit of Excellence on Exercise and Health (UCEES), and the Junta de Andalucia, Consejeria de Conocimiento, Investigacion y Universidades and European Regional Development Fund: (SOMM17/6107/UGR); by Spanish Ministry of Science, Innovation, and Universities: (PRE2018085440 and FPU19/01638); and by Spanish Ministry of Education, Culture, and Sport: (FPU15/01193). Funding for open access charge: Universidad de Granada/CBUA Sequence data of all testicular spermatozoa and negative control samples have been deposited in the National Centre for Biotechnology Information (NCBI) Sequence Read Archive (SRA) database (http://www.ncbi.nlm.nih.gov/sra) under the BioProject ID PRJNA643898. The preliminary results of this study were presented as a poster communication at the 35th Annual ESHRE Meeting (Vienna, 2019).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.Copan Italia S.p.A Inc.ClearblueSPD Swiss Precision Diagnostics GmbHSpanish GovernmentEuropean Commission RYC-2016-21199
SAF2017-87526-RFEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento: MENDO B-CTS-500-UGR18
Junta de Andalucia PAIDI P20_00158University of Granada, Plan Propio de Investigacion 2016, Excellence actions: Units of ExcellenceUnit of Excellence on Exercise and Health (UCEES)Junta de Andalucia
Consejeria de Conocimiento, Investigacion y UniversidadesEuropean Commission SOMM17/6107/UGRSpanish Government PRE2018085440
FPU19/01638
FPU15/01193Universidad de Granada/CBUA Sequence
BioProject PRJNA64389
