High-throughput sequencing of 16S rRNA amplicons characterizes gut microbiota shift of juvenile sea cucumber Apostichopus japonicus feeding with three antibiotics

Abstract

Sea cucumber Apostichopus japonicus is an important marine economic species in Asian countries due to its profound nutritional and medicinal value. So far, with the rapid development of intensifi ed artifi cial aquaculture of sea cucumbers, the use of antibiotics is still an inexpensive and dispensable way to treat pathogenic infections, especially during the nursery phase. However, there is little information on the eff ects of antibiotics on the intestinal microbiota of sea cucumber. Therefore an Illumina based sequencing method was used to examine the intestinal bacterial composition of juvenile A . japonicas following diets with three typical antibiotics (tetracycline, erythromycin, and norfl oxacin) under 15, 30, and 45 d. The fi ndings reveal that diff erent antibiotics have distinct eff ects on the growth performance of juvenile sea cucumbers. However, the richness and diversity of microbiota were barely aff ected by antibiotics but the community composition alterations indicated that the three antibiotics exhibited their respective patterns of reshaping the intestinal bacteria of juvenile sea cucumbers. In common, the abundance of some sensitive genera with helpful functions, such as Thalassotalea , Shewanella , Sulfi tobacter , and Halomonas decreased signifi cantly with exposure to antibiotics and the abundance of multiple potential pathogenic-and suspected antibiotic-resistant microorganisms like Arcobacter , Leucothrix , and Clostridium_sensu_stricto_1 was found increased signifi cantly in the antibiotic groups. These results suggest that low doses of antibiotics could aff ect the composition of the intestinal microbiota of sea cucumbers and might increase the risk of infection of the hosts. This study could help us to explore how antibacterial compounds modify the gut microbiota of sea cucumbers and provide theoretical guidance in hatchery management by scientifi c antibiotic use in sea cucumber mariculture.

Antibiotics Modulate Intestinal Regeneration

“…Therefore, at first glance, antibiotics do not appear to have a major effect on the organisms since the survival rate is not altered. Our results can be compared to studies in the sea cucumber Apostichopus japonicus , where Zhao et al [ 82 ] explored the effect of the antibiotics erythromycin, tetracycline, and norfloxacin for 15, 30, and 45 d. They showed that while they altered the growth rate of these animals in a time-dependent manner, there was no effect on their survival [ 82 ]. This contrast between antibiotics’ effect on survival versus physiology has been seen in other organisms.…”

The Role of the Microbiota in Regeneration-Associated Processes

“…In a different study, Yamazaki and colleagues found that Rhodobacterales are the third most abundant order in the fecal microbiota of A. japonicus, and the relative abundances were significantly higher in larger animals than in smaller individuals (Yamazaki, et al, 2016). However, the subsequent article by Zhao and colleagues reported a decreased relative abundance of Rhodobacteraceae in A. japonicus juveniles when treated with either tetracycline or erythromycin, but an increase in sea cucumber survival and body weight (Zhao et al, 2019). The above summarized studies demonstrate how bacteria metabolic activity might play a key role in providing the energy source to hosts to facilitate or activate their cellular and molecular process.…”

“…The orders Rhodobacterales, Oceanospirillales, and Desulfobacterales were more abundant in larger animals. The long-term effects, in terms of growth and disease resistance, of disrupting the bacterial community of A. japonicus sea cucumbers by using antibiotics was also explored (Zhao et al, 2019). Interestingly, after administering different antibiotics (tetracycline, erythromycin, or norfloxacin), it was observed that some antibiotics increased the growth of the animals yet weakened their immunological system.…”

“…Antibiotics have also been shown to have long-term effects on holothurian growth and disease resistance. In an experiment where antibiotics (tetracycline, erythromycin, or norfloxacin) were administered to disrupt the bacterial community, some antibiotics increased the growth of sea cucumbers, yet appear to inhibit the animal immune system (Zhao et al, 2019).…”

Unraveling the effects of sulfamethoxazole on the composition of gut microbiota and immune responses in Stichopus variegatus

“…However, sulfamethoxazole has the characteristics of low bioavailability and high water solubility. The large amount of unabsorbed antibiotics not only poses a serious ecological threat to the environment, but also severely disturbs the intestinal homeostasis of organisms and leads to the emergence of antibiotic-resistant strains ( Li et al, 2015 ; Zhao et al, 2019b ). Studies showed that although antibiotics control the occurrence of diseases to some extent, it also affects the structure of animal intestinal microflora, studies on the changes of intestinal microflora in aquaculture animals caused by antibiotics also attracted attention ( Stanton, 2013 ; Wang R. X. et al, 2015 ; Zhao et al, 2019b ).…”