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Journal : Meditory : The Journal of Medical Laboratory

ANTIBACTERIAL ACTIVITY SCREENING OF BACTERIAL ISOLATES ASSOCIATED WITH SEAWEEDS Caulerpa lentillifera AR, Sunthio Barran Cia; Indraningrat, Anak Agung Gede; Widhidewi, Ni Wayan; Wijaya, Made Dharmesti; Antara, Kadek Lila; Choe, Daegeun
Meditory : The Journal of Medical Laboratory Vol 13, No 1 (2025): Meditory, Volume 13 No. 1 Tahun 2025
Publisher : Jurusan Teknologi Laboratorium Medis, Poltekkes Kemenkes Denpasar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33992/meditory.v13i1.4051

Abstract

Background: Caulerpa lentillifera is a species of green algae that has been cultivated widely in Indonesia for its nutritional contents and health benefit. This seaweed builds a strong association with bacterial community which play an important role in synthesizing various secondary metabolites including antibacterial activity. Aims:The research aim to explore the symbiotic relationship between C. lentillifera and its associated bacterial community, focusing on the potential of these bacteria to produce antibacterial metabolites.Methods:Bacterial cultivation was performed on three different media namely nutrient agar, plate count agar, and zobell marine agar. The obtained bacterial isolates were identified morphologically and subsequently were screened for their antibacterial activity based on perpendicular cross streak method against Staphylococcus aureus ATCC 25923, Streptococcus mutans FNCC 0405, Escherichia coli ATCC 25922, and Klebsiella pneumoniae ATCC 700603. Results: 20 out of 28 bacterial isolates inhibited against at least one of the bacterial targets. Bacterial isolate encoded as NAR9 showed as the most promising bacterial isolates with length inhibition of 19 mm against S. mutans FNCC 0405. Amplification of 16S rRNA gene fragment of the NAR9 bacterial isolate followed by Sanger sequencing showed that the isolate NAR9 has been phylogenetically related to Marinobacter hydrocarbonoclasticus. Conclusion: Overall, this research provides a preliminary result of the untapped potential of bacteria associated with C. lentillifera as the source of antibacterial activity. 
BACILLUS SP RM3 ISOLATED FROM MANGROVE FOREST HAS POTENTIAL AS ANTIBACTERIAL ACTIVITY AND CYTOTOXICITY Maheswari, Ida Ayu Kartika; Indraningrat, Anak Agung Gede; Paramasatiari, Anak Agung Ayu Lila; Choe, Daegeun
Meditory : The Journal of Medical Laboratory Vol 13, No 1 (2025): Meditory, Volume 13 No. 1 Tahun 2025
Publisher : Jurusan Teknologi Laboratorium Medis, Poltekkes Kemenkes Denpasar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33992/meditory.v13i1.4073

Abstract

Background: Antibacterial resistance is a critical health concern, driving the search for new compounds from natural sources such as mangrove-associated bacteria, which produce diverse secondary metabolites.Objective:  This research focused on studying the bioactivity of the extract of Bacillus sp. RM3, previously isolated from mangrove forests through an extraction method using ethyl acetate solvent.Methods: The Bacillus sp. RM3 isolate was fermented in ISP-2 media and extracted with ethyl acetate. The resulting crude extract was tested for antibacterial activity using the Kirby-Bauer method against Staphylococcus aureus ATCC 25923, Streptococcus mutans FNCC 0405 (Gram-positive), Escherichia coli ATCC 25922, and Klebsiella pneumoniae ATCC 700603 (Gram-negative). Cytotoxic effects were assessed via the Brine Shrimp Lethality Assay (BSLT).Results: The ethyl acetate extract displayed moderate antibacterial activity, evidenced by inhibition zone diameters between 5 to 10 mm. Triplicate measurements revealed the following average inhibition zone diameters: E. coli (9.65±1.62 mm), K. pneumoniae (7.88±1.92 mm), S. aureus (7.77±1.26 mm), and S. mutans (7.03±0.99 mm). Furthermore, the BSLT assay revealed an LC50 value of 504.586 ppm, which indicates the extract was toxic (LC50 1000 ppm).Conclusions: Overall, these results indicate the potential of Bacillus sp. RM3 isolate as a producer of antibacterial and cytotoxic compounds