Exploratory metagenomics of bacterial diversity in semen from indonesian native roosters supplemented with curcumin and penicillin-streptomycin

In the world of animal agriculture, the health of a flock often begins long before the first egg is laid or the first chick hatches. It starts with the quality of the sperm used for breeding. For farmers raising native chickens, known in Indonesia as Kampung chickens, preserving the vitality of this genetic material is a delicate task. When semen is collected and stored, it is not merely a sterile fluid; it is a living ecosystem teeming with microscopic bacteria. These tiny organisms can either coexist peacefully with the sperm or, if left unchecked, multiply rapidly and damage the sample, rendering it useless for reproduction. To manage this, scientists often add substances to the storage liquid, known as a diluent, to either kill harmful bacteria or encourage a stable environment. Two such substances have drawn attention: a common antibiotic mixture and a bright yellow compound found in the spice turmeric, known as curcumin. The question researchers face is not just whether these additives stop bad bacteria, but how they reshape the entire community of microbes living within the semen, and whether they do so in a way that keeps the sample healthy.

A team of scientists set out to explore this question by looking directly at the bacterial diversity inside the semen of Indonesian native roosters. They collected samples and divided them into five groups to test different storage conditions. One group served as a baseline, stored without any additives. The other four groups received specific treatments: three received different amounts of curcumin, measured at 10, 20, and 30 micromolar, while the final group received a standard dose of penicillin-streptomycin, a common antibiotic combination. All samples were kept at a cool 5 degrees Celsius for 24 hours, a typical storage period, before the researchers analyzed the microbial life inside them. To see what was there, they used a method that reads the genetic code of the bacteria, allowing them to identify which species were present and how many different types existed.

The results revealed a fascinating stability in the core community of bacteria. Regardless of which treatment the semen received, two specific types of bacteria, one an uncultured species of Saccharofermentans and the other Porphyromonas somerae, remained the most dominant and consistent members of the group. They formed the stable foundation of the microbiome, surviving the storage period in every single sample. However, the way the additives changed the rest of the community differed significantly. The antibiotic treatment acted as a powerful, sweeping force. It drastically reduced the total number of different bacterial types found in the sample, effectively clearing out much of the microbial variety. While this group ended up with the most even distribution of the few remaining species, it represented a sharp, immediate shift in the ecosystem.

In contrast, the curcumin treatments showed a more nuanced effect. As the amount of curcumin increased, the variety of bacteria decreased in a steady, predictable pattern, but the overall balance of the community remained intact. The researchers observed that curcumin did not simply wipe out the bacterial world; instead, it acted like a selective filter. It suppressed the growth of potentially harmful bacteria without destroying the entire ecosystem or causing opportunistic, unwanted species to take over. This approach maintained the structural integrity of the semen environment while still managing the microbial population. The study suggests that while antibiotics work quickly and dominantly to suppress bacterial growth, curcumin offers a way to modulate the microbial community in a more balanced manner. By keeping the environment stable and preventing the explosion of bad bacteria, curcumin appears to preserve the health of the chicken semen without the drastic disruption caused by the antibiotic treatment.