Probiotic Role of Salt Pan Bacteria in Enhancing the Growth of Whiteleg Shrimp, Litopenaeus vannamei

Development of probiotics to improve the growth of cultured species is a key to sustainable aquaculture. The present study investigates the potential of salt pan bacteria as probiotics for Litopenaeus vannamei. Halotolerant bacteria (100) were screened for enzyme production and mucus adhesion in vitro. The bacteria (SK07, SK27, ABSK55, FSK444, TSK17, TSK71) exhibiting promising enzyme activity and adhesive property in vitro were selected to study their effect on the growth and metabolism of L. vannamei in vivo. When administered to shrimps individually as a water additive in experiment I, SK07, SK27 and TSK71 significantly (p < 0.05) increased shrimp weight as compared to the control. In experiment II, a lyophilized bacterial consortium (test) prepared with the four best isolates (SK07, SK27, ABSK55, TSK71), exhibited significantly higher weight gain of shrimps, better feed efficiency and final yield as compared to control. Total enzyme activity (amylase, protease, lipase) in the shrimp gut was significantly higher in the test than the control. The four isolates showed 99% nBLAST similarity with Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus licheniformis and Pseudomonas sp. Presence of these bacteria in the shrimp gut was confirmed by using specific PCR-based molecular probes and 16S rDNA sequencing. Safety evaluation by antibiotic susceptibility test and hemolytic activity test indicated that the bacteria are safe as bioinoculants. The increased enzyme activity by colonisation of the isolates in the shrimp gut, along with improved growth and feed utilisation efficiency, strongly confirms that these salt pan bacteria are prospective probiotics in shrimp aquaculture.

Lithium and Boron in Calcified Tissues of Vicuna and Their Relation to Chronic Exposure by Water Ingestion in The Andean Lithium Triangle

Vicuna is a wild, endangered species of Andean camelid living in the hyperarid Andean plateau. In the central part of the plateau, the Lithium Triangle defines a zone with lithium-rich salt pans. Brine pools naturally form within the salt pans, and the adaptation strategy of vicuna consists of drinking from brine pools. Together with reporting the first chemical data on vicuna bones and teeth, we analyzed lithium, boron, and arsenic in water and brines, with the aim of assessing their relation to chronic exposure by water ingestion. We collected and analyzed bones of vicuna specimens lying in an Andean salt pan, together with brine and water samples. Brine and water samples are highly saline and contain large amounts of lithium, boron, and arsenic. Lithium (13.50-40 mg kg^-1 ) and boron (40-46.80 mg kg^-1 ), but not arsenic, were found in the vicuna bones and teeth. Based on our results and on previously reported data on human tissues in the Andes, we conducted statistical assessments of the relationships between lithium and boron in body tissues and water samples, and discuss their environmental significance in the context of the Lithium Triangle. Environ Toxicol Chem 2019;39:200-209. © 2019 SETAC.

In-vitro antimicrobial activity of marine actinobacteria against multidrug resistance Staphylococcus aureus

OBJECTIVE

To investigate the antibacterial activity of marine actinobacteria against multidrug resistance Staphylococcus aureus (MDRSA).

METHODS

Fifty one actinobacterial strains were isolated from salt pans soil, costal area in Kothapattanam, Ongole, Andhra Pradesh. Primary screening was done using cross-streak method against MDRSA. The bioactive compounds are extracted from efficient actinobacteria using solvent extraction. The antimicrobial activity of crude and solvent extracts was performed using Kirby-Bauer method. MIC for ethyl acetate extract was determined by modified agar well diffusion method. The potent actinobacteria are identified using Nonomura key, Shirling and Gottlieb 1966 with Bergey's manual of determinative bacteriology.

RESULTS

Among the fifty one isolates screened for antibacterial activity, SRB25 were found efficient against MDRSA. The ethyl acetate extracts showed high inhibition against test organism. MIC test was performed with the ethyl acetate extract against MDRSA and found to be 1 000 µg/mL. The isolated actinobacteria are identified as Streptomyces sp with the help of Nonomura key.

CONCLUSIONS

The current investigation reveals that the marine actinobacteria from salt pan environment can be able to produce new drug molecules against drug resistant microorganisms.