Isolation and characterisation of bioflocculant-producing bacteria from mud crab (Scylla sp.) aquaculture ponds

Shahadat, Hossain and Ahmad Shukri Zuhayra Nasrin and Rohisyamuddin Othman and Ho, Khor Wai and Helena, Khatoon and Zahidul, Islam and Mahmud, Minhaz Tashrif and Kamaruzzan, Amyra Suryatie and Abdul Rahim Ahmad Ideris and Nor Azman Kasan (2023) Isolation and characterisation of bioflocculant-producing bacteria from mud crab (Scylla sp.) aquaculture ponds. Journal of Sustainability Science and Management (Malaysia), 18 (8). pp. 98-115. ISSN 2672-7226

Mud crab is one of the most delectable and in-demand foods in the world, but there is a shortage of it because of the greater death rate of their seeds in the hatchery owing to disease, malnutrition, and poor water quality. The use of Biofloc Technology (BFT), a widely used, ecologically friendly technique that is effective for good nutrition, healthy cultures, and good water quality, has not yet been tried for mud crab farming. This study aimed to isolate and characterise potential Bioflocculant-producing Bacteria (BPB) from a mud crab, Scylla sp. aquaculture ponds to apply them as an inoculum of mud crab biofloc system. BPB was isolated from the water and sediment using the serial dilution, spread plate, and streaking plate methods on marine agar media, Yeast Peptone Agar (YPG) media, and enrichment media. Morphological, biochemical, and 16s rRNA molecular approaches were performed to screen the bacteria, where the flocculating activity of the bacterial species was determined using the kaolin clay suspension method. A total of 88 isolates were successfully found from both water (82 isolates) and sediment (6 isolates) samples. 18 bacteria isolates showed floc-forming characteristics such as slimy and milky appearance on YPG agar and enrichment media and were identified as Bacillus cereus, B. tropicus, B. infantis, Vibrio alginolyticus, Priestia flexa, and Micrococcus luteus. B. tropicus showed the highest (95% ± 0.135) flocculation activity, whereas M. luteus showed the lowest (74.81% ± 5.985) flocculation activity. Six prospective biofloc bacteria with increased flocculation activity were identified in this study, and these can be used in further studies on mud crab hatchery operations.

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Abstract

Mud crab is one of the most delectable and in-demand foods in the world, but there is a shortage of it because of the greater death rate of their seeds in the hatchery owing to disease, malnutrition, and poor water quality. The use of Biofloc Technology (BFT), a widely used, ecologically friendly technique that is effective for good nutrition, healthy cultures, and good water quality, has not yet been tried for mud crab farming. This study aimed to isolate and characterise potential Bioflocculant-producing Bacteria (BPB) from a mud crab, Scylla sp. aquaculture ponds to apply them as an inoculum of mud crab biofloc system. BPB was isolated from the water and sediment using the serial dilution, spread plate, and streaking plate methods on marine agar media, Yeast Peptone Agar (YPG) media, and enrichment media. Morphological, biochemical, and 16s rRNA molecular approaches were performed to screen the bacteria, where the flocculating activity of the bacterial species was determined using the kaolin clay suspension method. A total of 88 isolates were successfully found from both water (82 isolates) and sediment (6 isolates) samples. 18 bacteria isolates showed floc-forming characteristics such as slimy and milky appearance on YPG agar and enrichment media and were identified as Bacillus cereus, B. tropicus, B. infantis, Vibrio alginolyticus, Priestia flexa, and Micrococcus luteus. B. tropicus showed the highest (95% ± 0.135) flocculation activity, whereas M. luteus showed the lowest (74.81% ± 5.985) flocculation activity. Six prospective biofloc bacteria with increased flocculation activity were identified in this study, and these can be used in further studies on mud crab hatchery operations.

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Item Type:	Article
AGROVOC Term:	Scylla serrata
AGROVOC Term:	biofloc technology
AGROVOC Term:	water treatment
AGROVOC Term:	Bacteria
AGROVOC Term:	flocculation
AGROVOC Term:	research
AGROVOC Term:	sampling
AGROVOC Term:	data analysis
AGROVOC Term:	disease control
AGROVOC Term:	hatcheries
Geographical Term:	Malaysia
Uncontrolled Keywords:	Biofloc technology, BPB, 16s rRNA sequencing, flocculation activity, mud crab.
Depositing User:	Nor Hasnita Abdul Samat
Date Deposited:	20 Mar 2025 04:19
Last Modified:	20 Mar 2025 04:19
URI:	http://webagris.upm.edu.my/id/eprint/1632

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