Antipathogenic Activity of Acroporid Bacterial Symbionts Against Brown Band Disease-Associated Bacteria

Abstract

The coral reefs’ condition in most regions in Indonesia has been declining due to coral diseases, such as Brown Band Disease (BrBD). A treatment for BrBD involves the use of biological control agents that have antagonistic properties against disease-causing agents. This study aimed to isolate bacteria from healthy hard coral, those associated with BrBD, and those that had bioactivities against BrBD. Sampling and identification of corals and BrBD were carried out in March 2015 at the Marine National Park of Karimunjawa. Bacteria from healthy and infected corals were isolated and purified. The isolates were subjected to antipathogenic assay using overlay and agar diffusion methods. Finally, molecular identification of active bacteria was carried out using the 16S rRNA gene amplification. As many as 57 bacterial isolates were obtained from healthy coral, as well as four bacterial isolates from coral with BrBD symptoms. A total of 15 bacterial isolates (26%) showed antipathogenic activity against BrBD-associated bacteria. Three isolates with the strongest antipathogenic activities, i.e., GAMSH 3, KASH 6, and TAPSH 1 were identified by 16S rRNA gene sequences. The results showed that they were aligned to Virgibacillus marismortui (97%), Oceanobacillus iheyensis (97%), and Bacillus cereus (96%), respectively.

Potential of antagonistic activity from associated bacteria from healthy and bleaching acropora corals of Blitar Waters, East Java, Indonesia

“…The antagonistic activity of coral-associative bacteria was tested using the double-layer method [15]. Healthy coral bacterial isolates were dotted on the surface of Zobell 2216E agar medium and incubated for 96h at 27°C.…”

Screening of sponge-associated bacteria to control vibriosis in vannamei shrimp (Litopenaeus vannamei)

“…PCR reaction with a total of 25μL consisted of 2.5 μL DNA template, each primer of 2.0 μL, ddH2O of 6 μL, and mix PCR (MyTaqTMRed Mix-Bioline) of 12.5 μL. The amplification reaction was carried out in a Thermal Cycler (BIO-RAD) T100 in accordance with Amalia et al (2021), the specific steps are as follows: Initial denaturation at 95°C for 3 minutes; 30 cycles of denaturation at 95°C for 1 minute, then annealing at 55°C for 1 minute, extension at 72°C for 1 minute, and final extension at 72°C for 7 minutes. The PCR products were examined using gel electrophoresis with agarose 1%, and the result was visualized by using UVIDoc HD5 (UVITEC Cambridge, UK).…”

“…Molecular identification was conducted for the most active sponge-associated bacteria (Table 1) by comparing 16S rRNA genes of the isolates with similar bacteria (Amalia et al 2021). As demonstrated in Figure 2, all isolates have amplicons with a size of approximately 1,500 bp (Amalia et al 2021), indicated by the bands in the 1,500 bp DNA ladder region.…”

“…Molecular identification was conducted for the most active sponge-associated bacteria (Table 1) by comparing 16S rRNA genes of the isolates with similar bacteria (Amalia et al 2021). As demonstrated in Figure 2, all isolates have amplicons with a size of approximately 1,500 bp (Amalia et al 2021), indicated by the bands in the 1,500 bp DNA ladder region. The BLAST homology of 16S rRNA sequence result revealed that eight isolates belong to Bacillus sp., Bacillus wiedmannii, Bacillus cereus, Virgibacillus salarius, Bacillus aerius, B. paramycoides, B. thuringiensis, and B. altitudinis.…”