Physicochemical characterization of chitosan/agar blend gel beads prepared via the interphase method with different drying techniques.

In this study, natural and biodegradable chitosan/agar blend gel-beads were prepared via the interphase method. Agar was added to chitosan dissolved in aqueous acetic acid and stirred homogenously under a controlled temperature. With a syringe, the gel solution were added and dropped wisely to the oily phase. The gel-beads were dried at two different conditions: in the oven at 60°C, and in the freeze dryer for 12 hours. The physicochemistry of the resulting materials were subsequently characterized by fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). FTIR results confirmed the formation of intermolecular hydrogen bonding between the amino and hydroxyl groups of chitosan and the hydroxyl groups of the agar. From the TGA results, we noticed that heat stability of the chitosan/agar blend beads was high compared to its individual components. SEM micrographs showed regular shaped chitosan beads with spherical forms and rough surfaces with pores

Molecular - bioassay methods: complementary approaches for development and evaluation of anti infective marine product

The current trends in drug development employ biotechnological approach to expedite effective drugs discovery program. Molecular biotechnological approach, in combination with bioassay, is practical in attaining effective drugs since the two platform methods complement each other by target identification, as well as compound screening, profiling and validation. The research on antimicrobial properties of marine products, targeting membrane function through membrane permeabilizing ability, has been carried out using molecular- and cellular-based approaches. The molecular approach for the screening of membrane permeabilizing peptide gene in local marine organism was found to successfully amplify a conserved gene sequence of the antibacterial peptide gene. Bacterial membrane permeabilizing ability of the methanolic extract was indicated through alteration of mRNA nucleotides, genes coding for membrane development in Staphylococcus aureus (MRSA) and the non-methicillin resistant strains. The alteration of nucleotides affected the transportation of lysine to the phospholipid bilayer of bacterial membranes, resulting in incomplete membrane structure, eventual lysis and cell death. Through cellular approaches, the methanolic extract of marine organisms affecting membranes of S. aureus, were confirmed. In specific, the extract showed a good inhibitory activity against S. aureus through plate and tube methods, and the cellular assay illustrated the penetration of fluorescence dye in treated bacterial pathogens, similar to the pathogens treated with positive antibiotic controls. The research constitutes a scientific advancement in the field of medical treatment of drug resistant bacteria and a forefront study of drugs discovery program focusing on drugs target genes

Growth and length-weight relationship of Penaeus monodon (Fabricius) cultured in artificial sea water.

Post larvae of Penaeus monodon were cultured in a tank with artificial sea water between November 2009 and February 2010. Length and weight of the specimens were taken every seven days interval for the study of growth and length-weight relationship. The overall average growth rate was estimated at 0.36 mm per day. The mean daily growth rate was 0.53, 0.33 and 0.27 mm at the first, second and third month respectively. The mean body weight of the cultured specimens varied from 111.17 to 874.00 mg. Average growth of the body weight was estimated at 9.03 mg per day. The relative growth coefficient (b) and condition factor (a) was estimated at 2.94 and 0.00693. It is reveal that the exponent (b) of Penaeus monodon was very near to the isometric value (b = 3.0). So, the growth of P. monodon cultured in tank with artificial sea was isometric. It could be concluded that artificial sea water is feasible for culturing P. monodon when sea water is not available or sea water resource is further away from hatchery

Extraction of essential oil from Nigella sativa using supercritical carbon dioxide : study of antibacterial activity.

The antimicrobial activity of N. sativa essential oil obtained by supercritical fluid extraction by carbon dioxide was investigated against Gram Positive and Gram negative strains, isolated from clinical specimens. Best conditions for Black cumin oil extraction are obtained at 400 bar, 40°C and a solvent flow rate of 25 g min-1. The seed extracts were prepared by supercritical fluid extraction method. Filter paper discs impregnated with varying concentrations of N. sativa extract were tested by the disk diffusion method. Methicillin Resistant Staphylococcus Aureus (MRSA) ATCC strain (700968), E. coli ATCC strain (25922), E. coli 0157 ATCC strain (12799), Extended-Spectrum Beta-Lactamase (ESBL) Klebsiella pneumoniae ATCC strain (700603), Carbapenam Resistant acenitobacter Baumanii (CRAB) clinical strain and Vibrio cholerae 01 Ogawa and 0139 Bengal clinical strains were investigated. The inhibition zones of the Mueller Hinton agar in different extract concentrate ion showed that at 25 mg 20 μL-1, 50 mg 20 μL-1 and 100 mg 20 μL-1, the inhibition zones increased accordingly in S. aureu. However, N. sativa was found to be inactive against ESBL producers (E. coli and K. pneumoniae)

Molecular characterization of horseshoe crab anti-lipopolysaccharide factor C-peptide for hybridization-based detection method of gram negative bacteria.

Recent advances in molecular techniques have revolutionized the detection of microorganism. The development of a molecular-based technique for detection of the three different targets of Enterbacteriacae was undertaken. Primer and probe were designed based on specific pepted of novel hemolymph protein of horseshoe crabs (Factor C anti-LPS) Tachypleus tridentatus that is believed to be involved in the binds to the lipopolysaccharide of Escherichia coli, Salmonella and Vibrio cholerae. The aim of our study the exploit part of cell wall polysaccharide in the development of improved detection method based on molecular approaches. In the gene detection assay, Lipopolysaccharide gene of Salmonella, V. cholera and E. coil were hybridized to anti-LPS factor gene found in the biolysate of the marine animals. The wzm and wzt genes encoding O-polysaccharide genes were amplified in these pathogens and the LPS factor C were amplified from the marine lysate. Development of a PCR-based technique for detection of the food-borne pathogens particularly Sa Salmonella, V. cholera and E. coil were achieved. Thus rapid, sensitive and reliable techniques for the detection of food-borne pathogens developed

Detection of diarrheagenic Escherichia coli isolated using molecular approaches.

Escherichia coli strains are among the major bacterial causes of diarrheal illness. There are now seven classes of diarrheagenic E. coli (DEC), namely enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC), enteroinvasive E. coli (EIEC), enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC), diarrhea-associated hemolytic E. coli (DHEC) and Cytolethal Distending Toxin (CDT)-producing E. coli. Due to the need for costly and labor-intensive diagnostic procedures, identification of DEC is difficult at standard laboratories. Therefore, Polymerase Chain Reaction (PCR) or dot blot has been used for genetic detection of DEC of 25 E. coli isolates from different sources. Amplification of eae (277 bp), bfp (266 bp), stx1 (154 bp), EAST (94 bp), stx2 (698 bp) and elt (450 bp) genes of a single product in separate reactions was produced. PCR showed ability to amplify and detected genes of the most common important categories of diarrheagenic E. coli isolates of different sources, it is possible implementation of this technique to diagnosis water, foodborne outbreaks related to E. coli. Dots blot and sequence analysis used to confirm the results of PCR

Herbal sensitivity of Pseudomonas bacteria isolated from cultured tilapia with useful applications in vaccine preparation.

The antibacterial activity of certain commercial antibiotics and common herbs was evaluated against pathogenic Pseudomonas fluorescens, Pseudomonas putida and Pseudomonas aeruginosa isolated from Malaysian and Egyptian cultured fish, mainly tilapia. A suspension of freshly cultured isolates was prepared (with 0.5 OD) and 100 μL of this suspension was spread over the Muller’s Hinton agar plates. The antibiotic discs were inoculated on each cultured plate while the herbal extracts were soaked on Whatman filter paper (20 μL each) that have been cut into discs and later inserted on to bacteria-cultured plates to screen their sensitivity to both antibiotics and herbs. Double-fold dilution was used to determine the Minimal Inhibitory Concentration (MIC) for the effective herbs at 100, 50, 25, 12.5 and 6.25%. Results revealed high resistance of the tested bacteria against most of the screened antibiotics except Ciprofloxacin. With regard to herbal sensitivity, only Origanum vulgare showed effectiveness and inhibition zone against all isolates. The MIC ranged from 15-40% for both Egyptian and Malaysian isolates. Thus, Origanum vulgare is recommended as a feed additive for cultured fish and can also be applied for inactivated and live-attenuated Pseudomonas vaccines’ preparation

Pathogenicity of Aeromonas hydrophila in giant freshwater prawn; Macrobrachium rosenbergii, cultured in East Malaysia

Aeromonas infections are becoming a major risk factor in commercial aquaculture and it has been reported that a wide variety of fish and shellfish species are susceptible to this infection. In this study, 3 isolates of Aeromonas hydrophila were isolated from giant freshwater prawn (Macrobrachium rosenbergii) cultured in Kuala Pilah Simbilan Nigri in East Malaysia. Conventional and rapid identification systems (API 20E strips) were used for preliminary identification based on the biochemical characters of the isolated bacteria. On the other hand, polymerase chain reaction (PCR) using the universal primer; 16S rRNA, was done as an accurate and confirmatory identification. The virulence of A. hydrophila was determined using a pathogenicity test via I/M injection. The results revealed that the isolated bacteria were identified as A. hydrophila that revealed a high degree of similarity (98%) to the NCBI or Genbank database. Based on pathogenicity test results, LD50 was determined as 1×106 CFU/50µl, while 1×107 CFU/50µl induced 100% mortality in the experimentally injected prawns. Histopathological changes were found in several organs including gill, hepatopancreas and heart. Those changes were mainly, melanisation, tissue erosion and necrosis, infiltration and hyperplasia of gill lamellae and mild or massive haemocyte reaction in the infected organs

Screening of Malaysian indigenous microalgae for antioxidant properties and nutritional value

Fourteen indigenous microalgal samples from Malaysia were isolated, purified and cultured from fresh,brackish and marine waters. The ability of the microalgae to be natural sources of antioxidants was studied by a screening test using three antioxidant chemical assays[ferric thiocyanate (FTC), thiobarbituric acid (TBA) and 1, 1’-diphenyl-2-picrylhydrazyl (DPPH)]. The results showed that six microalgal methanolic crude extracts(Isochrysis galbana, Chaetoceros calcitrans, Scenedesmus quadricauda, Chlorella vulgaris, Nannochloropsis oculata and Tetraselmis tetrathele) were active in inhibiting the lipid peroxidation of linoleic acid. Among all the microalgae, I. galbana and C. calcitrans showed the highest antioxidant activity (>90%) in FTC and TBA assays, indicating that these microalgae might contain active compounds for protection from lipid peroxidation. Nutritional analyses were performed on microalgae with high antioxidant activities (I. galbana and C. calcitrans) in order to investigate their nutritive value. Both microalgae were found to be rich in nutrients. For examples, I. galbana had average percentage composition of protein, carbohydrate,and lipid, as 47.9±2.5; 26.8±0.2; 14.5±1.4%, respectively,while the corresponding values for C. calcitrans were 36.4± 1.7; 27.4±3.0; 15.5±0.9%. In addition, they contained high levels of omega-3 polyunsatrated fatty acids (PUFA)(28.0%±0.7 in I. galbana and 28.5%±1.4 in C. calcitrans),omega-6 PUFA (6.5%±1.8 in I. galbana and 23.0%±2.5 in C. calcitrans) and a high composition of essential amino acids. This study illustrates that some microalgae such as I. galbana and C. calcitrans have the potential to be used as natural sources of antioxidants with high nutritional value