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The purpose of this study was to investigate the novelty and particularly of the culturable bacteria in seagrass bed and study its antibacterial activity crude extracts of the metabolites. A total of nine rhizosphere soil samples were collected from the seagrass bed ecosystems in Pearl Bay and Yuzhouping, Fangchenggang City. Five different isolation media were used to isolate and purify the culturable bacteria using the dilution spread plate method. The bacterial species were identified through PCR amplification and 16S rRNA sequencing. The antibacterial activity against four human pathogenic bacteria (methicillin-resistant Staphylococcus aureus, S. epidermidis, S. aureus and Acinetobacter baumannii) were screened with Kirby-Bauer method. The results were as follows: (1) A total of 42 culturable bacteria were isolated, belonging to 14 genera and 13 families, which included Streptomyces, Vibrio, Bacillus, Shewanella, Microbacterium, Brevibacterium, Staphylococcus, Sphingomonas, Rothia, Psychrobacter, Pseudonocardia, Photobacterium, Halomonas, and Shigella. The genus Streptomyces was the dominant bacterium. (2) Antibacterial activity showed that six bacteria exhibited strong inhibitory activity against at least two or more human pathogenic bacteria, which included Vibrio (1 strain), Rothia (1 strain), and Streptomyces (4 strains). The studies show that the rhizosphere soil microbial resources of halophytes in the seagrass bed in Fangchenggang sea area are novel and unique, and Streptomyces has a strong antibacterial activity, which provides a new source for the research and development of new antibiotics drugs. [ABSTRACT FROM AUTHOR]

Seagrasses demonstrate complex ecological functions, and their morphological and physiological indicators are affected by various environmental factors. In this study, we conducted six sampling surveys of a Thalassia hemprichii seagrass bed in Xincun Bay, Lingshui, Hainan in 2019. The morphological and physiological characteristics of seagrasses in January, March, May, July, September, and November of a single year were studied, and the effects of various environmental factors on the morphological and physiological characteristics of T. hemprichii were analyzed. The results demonstrated markedly differences in leaf length and width, rhizome length and thickness, and root length across different months. The highest value [(15.05±6.13) cm] of leaf length occurred in May, and the lowest value [(7.19±2.55) cm] in September. The highest [(11.93±1.68) mm] and the lowest [(8.73±1.96) mm] values for leaf width were recorded in November and September, respectively. The highest value [(5.22± 1.71) mm] for rhizome diameter occurred in November, and the lowest value [(4.06±0.74) mm] in March. The C content of the underground seagrass tissues was significantly different across months, with the highest value (31.23%±0.94%) in November and the lowest value (24.90%±3.48%) in March. Seawater temperature had a significantly positive correlation with leaf width and C content of the underground tissues. Salinity was significantly positively correlated with the leaf and rhizome lengths of T. hemprichii and had a negative relationship with the C content of the underground tissues. There was a significant positive correlation between pH and leaf length, leaf width, and C and N content of the underground tissues. The ammonium level in seawater was significantly positively correlated with the N content of aboveground tissues. Nitrate level of seawater was negatively correlated with the C/N ratio of the aboveground parts. There was a significant positive correlation between the dissolved inorganic nitrogen (DIN) in seawater and the N content of the underground parts. Sediment organic carbon had a negative relationship with leaf length and width, and rhizome growth. The results demonstrated that the growth of T. hemprichii in Xincun Bay was greatly affected by temperature, salinity, and pH. A high nutrient level in Xincun Bay may have a negative impact on T. hemprichii. In order to protect the T. hemprichii meadow, measures should be taken to limit the input of nutrients in Xincun Bay. The results of this study may provide data support and serve as a scientific basis for the restoration of declining seagrass.

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Copyright of Journal of Taiwan Fisheries Research is the property of Fisheries Research Institute, Council of Agriculture, Executive Yuan and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)