Isolation and characterization of agar-digesting Vibrio species from the rotten thallus of Gracilariopsis heteroclada Zhang et Xia.
Gracilariopsis heteroclada Zhang et Xia (Gracilariaceae, Rhodophyta) is one of the most studied marine seaweeds due to its economic importance. This has been cultivated extensively on commercial scale in the Philippines and other Asian countries. However, sustainable production of G. heteroclada in the Philippines could not be maximized due to the occurrence of rotten thallus disease. Thus, isolation and characterization of agar-digesting bacteria from the rotten thalli of G. heteroclada was conducted. A total of seven representative bacterial isolates were randomly selected based on their ability to digest agar as evidenced by the formation of depressions around the bacterial colonies on nutrient agar plates supplemented with 1.5% NaCl and liquefaction of agar. Gram-staining and biochemical characterization revealed that isolates tested were gram-negative rods and taxonomically identified as Vibrio parahaemolyticus (86-99.5%) and Vibrio alginolyticus (94.2-97.7%), respectively. It is yet to be confirmed whether these agar-digesting vibrios are involved in the induction and development of rotten thallus disease in G. heteroclada in concomitance with other opportunistic bacterial pathogens coupled with adverse environmental conditions.
Department of Natural Sciences, College of Arts and Sciences, University of St. La Salle, 6100 Bacolod City, Philippines. Electronic address: j.martinez@usls.edu.ph.
Joval N
JN
Martinez
Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 5128 Miag-ao, Iloilo, Philippines.
Philip Ian P
PI
Padilla
D000362:Agar / Q000378:metabolism*; D000461:Rhodophyta / Q000502:physiology*; D014733:Vibrio / Q000302:isolation & purification / Q000502:physiology*
D000362:Agar
Agar-digesting bacteria; Gracilariopsis heteroclada; Rotten thallus; Seaweed; Vibrio