Experimental methodologies and diagnostic procedures for acute hepatopancreatic necrosis disease (AHPND)

Acute hepatopancreatic necrosis disease (AHPND) is an emerging disease that has caused mass mortality in shrimp in many countries in Asia and South America. A new strain of Vibrio parahaemolyticus (VpAHPND), carrying one or more extrachromosomal ~70 kbp plasmids that encode homologues of the Photorhabdus insect-related (Pir) binary toxins (PirAvp and PirBvp) is the causative agent of AHPND. Bioassay challenges using immersion, reverse gavage and per os (feeding) treatments have been shown to induce the pathology characteristics of AHPND in experimentally infected shrimp. Moreover, a number of polymerase chain reaction (PCR) methods have been found to facilitate early detection of the disease. However, non-V. parahaemolyticus species close to Vibrio harveyi, Vibrio owensii and Vibrio campbellii have recently been identified as carrying pVA1-like plasmids, signifying that these plasmids are capable of being transmitted to different Vibrio species. AHPND is thus a threat and a serious concern for the aquaculture industry. Against this background, this paper presents an overview of experimental methodologies and diagnostic procedures for AHPND. It also includes fundamental findings related to the disease as guidelines which may be useful for further experimental work on AHPND and other similar shrimp diseases

Fabrication of polyethersulfone electrospun nanofibrous membranes incorporated with hydrous manganese dioxide for enhanced ultrafiltration of oily solution

In this work, a new type of ultrafiltration (UF) electrospun nanofibrous membranes (ENMs) incorporating hydrous manganese dioxide (HMO) nanoparticles was fabricated with the objective of improving properties of polyethersulfone (PES)-based membrane for synthetic oily solution treatment. Two treatments were carried out to improve the mechanical property and hydrophilicity of the PES-based membrane without compromising its porosity and water permeance. The first treatment involved the use of mixed solvents – dimethylformamide and n-methyl-pyrrolidinone (DMF/NMP) in which NMP is a high vapor pressure component that could enhance the mechanical properties of the nanofibrous by improving solvent-induced fusion of inter-fiber junction points. The second treatment involved the incorporation of specific amount of HMO nanoparticles in PES dope solution to enhance membrane hydrophilicity. Heat treatment was also adopted as an effective approach to strengthen and prevent delamination of the nanofibrous mat during UF process. The HMO-incorporated ENMs exhibited an excellent oil rejection (97.98% and 94.04%) and a promising water flux recovery (89.29% and 71.10%) when used to treat a synthetic oily solution containing 5000 or 10,000 ppm oil, respectively. The best promising HMO-incorporated ENM exhibited much higher magnitude of water productivity (>7000 L/m2h) without sacrificing oil removal rate. Most importantly, this nanofillers-incorporated membrane showed significantly lower degree of flux decline as a result of improved surface resistance against oil fouling and is of potential for long-term operation with extended lifespan. The promising mechanical and anti-fouling properties of the ENMs is potentially applicable in the efficient industrial oily effluents treatment when challenged with oil-in-water emulsions