There are several toxic microalgae species known as Harmful algal bloom (HAB) causing serious effects to the environment and economy. Knowledge on these groups of marine micro-flora is scanty and several areas remain unexplored. The present study focuses on the analysis of microalgal diversity in the Malabar coastal areas at Southwest and Northeast monsoon. The diatoms, dinoflagellates and total microalgal population were analysed and quantified. Predominant species were identified. Physicochemical parameters of the seawater at different time intervals and Correlation between diatoms, dinoflagellates and total microalgae population with physicochemical parameters were identified. From the analysis, a total of 53 diatoms and 15 dinoflagellates were identified. The predominant species including toxic or harmful bloom-forming were found to be Dinophysis caudata, Noctiluca scintillans, Prorocentrum lima and Tripos furca. The total microalgae population varied from 18,592 cells/L to 7,832 cells/L in the months of April and December. Dinoflagellates were positively correlated with salinity (r = 0.848; p = 0.008), nitrite (r = 0.752; p = 0.032) and total phosphorous (r = 0.734, p = 0.038). Diatoms were positively correlated with temperature (r = 0.804; p = 0.016) and nitrate (r = 0.774, p = 0.024). Total microalgal density was positively correlated with temperature (r = 0.825; p = 0.012) and nitrate content (r = 0.811, p = 0.15).

Background: Escherichia coli O157:H7 infection causes hemorrhagic colitis and is diagnosed based on symptoms such as cramps, stomach pain, and watery diarrhea. Shiga-like toxins (Verotoxin) produced by Escherichia coli O157:H7 damages endothelial cells of both kidney and brain, causing renal dysfunction and neurological problems. Methods: The present study focuses on identifying the prevalence of Verotoxin-producing Escherichia coli O157:H7 among diarrheal inpatients at Erode Government Hospital, India, and its antibiogram. Further, the Verotoxins were characterized by using SDS-PAGE analysis. A total of 123 samples were collected both from diarrheal stools, and strains from 37 samples (43.02 %) were found to have the presence of E. coli.  The organisms were identified based on their colony morphology on various media, cell morphology, and biochemical tests. The Shiga-like toxin production was identified by non-fermentation of sorbitol on SMAC agar plates. Confirmation of Shiga-like toxin was performed using agglutination assay.  Results: In total, 12 isolates showed agglutination and these isolates were confirmed to be E. coli O157:H7. The molecular weight of the Verotoxin was found to be between 20 and 29 kD. The antibiogram profile of the four isolated strains against 10 standard antibiotics was determined. Conclusion: The results of this study show the occurrence of drug resistance on hemorrhagic colitis causing E. coli O157:H7.

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Padina boergesenii is a distinctive small brown algae with rounded fronds growing to a length and diameter of 04 to 06 cm (1.6 to 2.4 in). P. boergesenii is widely present in the shallow water of tropical, subtropical and warm temperate areas. The present study aimed to investigate the anti-bacterial, anti-biofilm, antioxidant, anti-inflammatory and cytotoxicity activities of crude ethyl acetate extract of P. boergesenii. Anti-bacterial activity of crude ethyl acetate extract of P. boergesenii against Gram-positive and Gram-negative bacteria was determined using the well diffusion method. MIC of P. boergesenii against biofilm was carried out by the Resazurin method. Antioxidant potential was assessed by DPPH, FRAP, and the Hydrogen peroxide scavenging method. The anti-inflammatory activity was investigated using the albumin denaturation and heat-induced hemolysis method. Cytotoxicity activity of P. boergesenii against cell line L929 was analyzed by MTT assay. The maximum zone of inhibition obtained was 23 mm for Staphylococcus aureus, followed by 21 mm for Escherichia coli. Biofilm of Enterococcus faecalis showed higher resistance (MIC= 25.00±00.00 mg/mL). Biofilm of Acinetobacter baumannii was found to be most susceptible (MIC= 06.25±00.00 mg/mL). The IC50 value for the crude ethyl acetate extract P. boergesenii was 155.5 μg/mL for the DPPH method, 1567.18 μg/mL for the FRAP method, and 3098.27 μg/mL for the H2O2 method. The results of in vitro anti-inflammatory studies exhibited IC50= 122.33 μg/mL and 2522.40 μg/mL for albumin denaturation assay and heat-induced hemolysis method respectively. The crude ethyl acetate extract of P. boergesenii showed cytotoxicity against the growth of the L929 cell line. The present study suggested that the crude ethyl acetate extract P. boergesenii has potent antibacterial, anti-biofilm, antioxidant, anti-inflammatory and cytotoxicity activities. The bioactive components present in the P. boergesenii extract can be a promising source for pharmaceuticals.