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<p>Microbes are widely used in aquaculture to improve the growth, immunity, and water quality of the culture systems. The present study evaluates the probiotic potential of Bacillus strains isolated from mangrove sediments of Kumbalam, Kerala, India. Upon analysing diverse probiotic features, isolates named KM1 and KM2, which were later identified as <i>Bacillus cereus</i> and <i>Bacillus velezensis</i>, have displayed excellent characteristics. Both showed good antagonistic activity against aquatic pathogens such as <i>Aeromonas hydrophila</i>, <i>Vibrio parahaemolyticus</i>, and <i>Streptococcus agalactiae</i>. Antagonistic activity against <i>A. hydrophila</i> was highest, with the arbitrary unit of 24 ± 0.81 × 10<sup>4</sup> for <i>B. cereus</i> and 23.33 ± 0.57 × 10<sup>5</sup> for <i>B. velezensis</i>. The cultures also exhibited enzymatic activities viz. amylase, protease, and lipase with maximum activity for amylase with the zone diameter of 39.66 ± 0.577&#xa0;mm and 15.33 ± 0.471 for <i>B. cereus</i> and <i>B. velezensis</i> respectively. <i>B. cereus</i> demonstrated 58.21 ± 0.64 percent DPPH radical scavenging activity, while <i>B. velezensis</i> exhibited 60.23 ± 0.77. For <i>B. cereus</i>, the percentage of quorum quenching activity was determined as 98.34 ± 0.24 and for <i>B. velezensis</i>, it was 72.42 ± 0.30. The isolates also exhibited efficient ammonia and nitrite degradation, which make them useful as pond probiotics for water quality management. They were found to tolerate varying concentrations of bile salts and extreme pH conditions of gastrointestinal juice. Absence of virulence genes, non-haemolytic nature, and antibiotic susceptibility towards various antibiotics ensure the safety of probiotic strains. In-vitro assessments and safety studies identified <i>B. cereus</i> and <i>B</i>. <i>velezensis</i> as potential candidates to be used as probiotics in aquaculture.</p>

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Exploring the probiotic potential of B.cereus and B. velezensis associated with mangrove sediments in aquaculture

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  • 发表日期：

    2025年5月13日

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  • Greeshma James,
  • Vishnu Radhakrishnan,
  • Jifiriya Marathippallam Jamal,
  • Preena Prasannan Geetha,
  • Devika Pillai,
  • Rejish Kumar Vattiringal Jayadradhan

摘要

Microbes are widely used in aquaculture to improve the growth, immunity, and water quality of the culture systems. The present study evaluates the probiotic potential of Bacillus strains isolated from mangrove sediments of Kumbalam, Kerala, India. Upon analysing diverse probiotic features, isolates named KM1 and KM2, which were later identified as Bacillus cereus and Bacillus velezensis, have displayed excellent characteristics. Both showed good antagonistic activity against aquatic pathogens such as Aeromonas hydrophila, Vibrio parahaemolyticus, and Streptococcus agalactiae. Antagonistic activity against A. hydrophila was highest, with the arbitrary unit of 24 ± 0.81 × 104 for B. cereus and 23.33 ± 0.57 × 105 for B. velezensis. The cultures also exhibited enzymatic activities viz. amylase, protease, and lipase with maximum activity for amylase with the zone diameter of 39.66 ± 0.577 mm and 15.33 ± 0.471 for B. cereus and B. velezensis respectively. B. cereus demonstrated 58.21 ± 0.64 percent DPPH radical scavenging activity, while B. velezensis exhibited 60.23 ± 0.77. For B. cereus, the percentage of quorum quenching activity was determined as 98.34 ± 0.24 and for B. velezensis, it was 72.42 ± 0.30. The isolates also exhibited efficient ammonia and nitrite degradation, which make them useful as pond probiotics for water quality management. They were found to tolerate varying concentrations of bile salts and extreme pH conditions of gastrointestinal juice. Absence of virulence genes, non-haemolytic nature, and antibiotic susceptibility towards various antibiotics ensure the safety of probiotic strains. In-vitro assessments and safety studies identified B. cereus and B. velezensis as potential candidates to be used as probiotics in aquaculture.