Chilled and cryopreserved spermatophores of banana shrimp (Fenneropenaeus merguiensis): Effects of antibiotics on sperm quality and bacterial abundance

Disease prevention is a key issue in improving reproductive biotechnology for important and endangered aquatic species to minimize the risk of pathogen transmission and economic loss. This study investigated the effects of small-dose antibiotics on sperm viability and bacterial abundance in banana shrimp (Fenneropenaeus merguiensis) spermatophores during chilled storage and cryostorage. The experiment consisted of three treatments, no anti-biotic (control), 0.1% penicillin-streptomycin (PS), and 0.1% penicillin-gentamycin (PG). Antibioics were added into a sperm extender containing banana shrimp spermatophores. In the chilled storage and cryopreservation trials, the most significant (P < 0.05) improvement in sperm survival was observed in 0.1% PS-treated spermatophores over a 30-day period at 2-4 ?C and 6-month in a liquid nitrogen tank. Average sperm viability ranged from 46.3 +/- 3.5 to 95.7 +/- 0.6% and 78.8 +/- 1.1 to 95.7 +/- 1.0%, respectively. In the 0.1% PS-treated spermatophores, the numbers of culturable heterotrophic bacteria (CHB) fluctuated during 21-day chilled storage and decreased (P < 0.05) over 30-day storage compared to those in the control. The CHB count in cryopreserved spermatophores decreased (P < 0.05) with increasing storage time and was undetectable by day 7 of cryostorage. Pseudomonad bacteria were not observed in both chilled-stored spermatophores by 21 days post -storage and prefrozen spermatophores when 0.1% PS was incorporated into the sperm extender. The 0.1% PS treatment also inhibited the growth of culturable Vibrio in banana shrimp spermatophores during chilled storage and cryostorage. Several species of human and shrimp pathogens and spoilage bacteria, particularly Vibrio parahaemolyticus, V. metschnikovii, V. harveyi, Aeromonas media, A. sorbria, and Plesiomonas shigelloides were not found after 0.1% PS was added to the sperm extender. This study suggests that addition of 0.1% PS into the extender not only reduces the bacterial count of chilled and postthawed cryopreserved sperm of banana shrimp, but also had no adverse effect on sperm viability.