Biosynthesis of Silver Nanoparticles Using Bersama engleriana Fruits Extracts and Their Potential Inhibitory Effect on Resistant Bacteria

The absence of novel, safe, and effective bactericide is an urgent concern worldwide and remains a challenge in scientific communities. The unique proprieties of silver nanoparticles (SNPs) synthesized from plant extracts make them a suitable candidate to overcome these limitations. Herein, we synthesized SNPs from Bersama engleriana fruit (BEfr) extracts and determined their potential antibacterial activity and mode of action. SNPs were synthesized from BEfr methanolic fruit extracts at 25 and 70 ◦C, and the antibacterial effectiveness of SNPs against bacterial strains was investigated. The surface plasmon resonance peaked at 430.18 and 434.08 nm, respectively, for SNPs synthesized at 25 and 70 ◦C, confirming SNPs synthesis. BEfr-SNPs had minimum inhibitory concentrations (MIC) range of 0.234 to >50 µg/mL, which was 30-fold greater than extract alone (MIC of 500 µg/mL). BEfrSNPs-25 ◦C was potent against six bacterial strains (S. aureus, S. enterica, MRS. aureus, K. pneumonia, and S. pyogenes), with MIC range of 0.339 to 6.25 µg/mL. The mode of action of BEfr-SNPs-25 ◦C was achieved by an MRSA bacteria strain outer membrane and DNA nucleotide linkage. These results suggest that our synthesized SNPs, especially BEfr-SNPs-25 ◦C, demonstrated an enhanced antibacterial effect and could be potential candidates for bacterial infection treatment

Remediation of radioiodine using polyamine anion exchange resins

Two weak base anion exchange resins, Lewatit A365 and Purolite MTS9850, have been tested for the removal of aqueous iodide from conditions simulating nuclear waste reprocessing streams. pH variation and relevant co-contaminant addition (nitrate, molybdate and iodine) allowed for assessment of iodide extraction behaviour of each resin. Isotherm experiments were performed and maximum uptake capacities obtained exceed current industrial adsorbents, such as silver-impregnated zeolites. Maximum loading capacities, determined by Dubinin–Radushkevich isotherm, were 761 ± 14 mg g−1 for MTS9850 and 589 ± 15 mg g−1 for A365. Uptake for both resins was significantly suppressed by nitrate and molybdate ions. The presence of dissolved iodine in the raffinate however, was found to increase iodide uptake. This was explained by characterisation of the spent resin surface by infrared and Raman spectroscopy, which determined the presence of triiodide, indicating charge-transfer complex formation on the surface. Dynamic studies assessed the effect of co-contaminants on iodide uptake in a column environment. Data was fitted to three dynamic models, with the Dose-Response model providing the best description of breakthrough. In all cases iodide breakthrough was accelerated, indicating suppression of uptake, but capacity was still significant

Effect of environmental and nutritional conditions on the formation of single and mixed-species biofilms and their efficiency in cadmium removal

Remediation of contaminated water and wastewater using biosorption methods has attracted significant attention in recent decades due to its efficiency, convenience and minimised environmental effects. Bacterial biosorbents are normally deployed as a non-living powder or suspension. Little is known about the mechanisms or rates of bacterial attachment to surfaces and effect of various conditions on the biofilm development, as well as efficiency of living biofilms in the removal of heavy metals. In the present study, the effect of environmental and nutritional conditions such as pH, temperature, concentrations of phosphate, glucose, amino acid, nitrate, calcium and magnesium, on planktonic and biofilm growth of single and mixed bacterial cultures, were measured. Actinomyces meyeri, Bacillus cereus, Escherichia coli, Pseudomonas fluorescens strains were evaluated to determine the optimum biofilm growth conditions. The Cd(II) biosorption efficiencies of the mixed-species biofilm developed in the optimum growth condition, were investigated and modelled using Langmuir, Freundlich and Dubnin Radushkevich models. The biofilm quantification techniques revealed that the optimum concentration of phosphate, glucose, amino acid, nitrate, calcium and magnesium for the biofilm development were 25, 10, 1, 1.5, 5 and 0.5 g L−1, respectively. Further increases in the nutrient concentrations resulted in less biofilm growth. The optimum pH for the biofilm growth was 7 and alkaline or acidic conditions caused significant negative effects on the bacterial attachment and development. The optimum temperatures for the bacterial attachment to the surface were between 25 and 35 °C. The maximum Cd(II) biosorption efficiency (99%) and capacity (18.19 mg g−1) of the mixed-species biofilm, occurred on day 35 (Ci = 0.1 mg L−1) and 1 (Ci = 20 mg L−1) of biofilm growth, respectively. Modelling of the biosorption data revealed that Cd(II) removal by the living biofilm was a physical process by a monolayer of biofilm. The results of present study suggested that environmental and nutritional conditions had a significant effect on bacterial biofilm formation and its efficiency in Cd(II) removal

The relationship between properties of plant-based biochars and sorption of Cd(II), Pb(II) and Zn(II) in soil model systems

Plant based biochars are proposed as soil amendments to immobilize potentially toxic trace elements (PTEs), such as Cd(II), Pb(II) and Zn(II) and aid in soil restoration. However, the sorption capacity of biochar for these elements can vary widely depending on biochar nature and metal properties. Currently, there is no clear methodology to pre-screen biochars for their suitability as adsorbents for these elements. Therefore, to facilitate biochar selection for application in soil restoration, this study explored the relationships between the physico-chemical properties of five plant-based biochars and their capacity to immobilize Cd(II), Pb(II) and Zn(II). Batch experiments using synthetic soil pore water were used to assess the sorption of these elements. The sorption isotherms described by the Hill model indicated that PTE sorption capacity followed the order Pb(II) > Cd(II) >Zn(II) regardless of biochar type in mono-element systems. Preferential sorption of Pb(II) limited the immobilization of Cd(II) and Zn(II) in multi-element systems. ATR-FTIR and SEM-EDX spectroscopy studies indicated that Cd(II) and Pb(II) sorption was mediated by complexation with carboxylic groups, cation–π interactions and precipitation with phosphates and silicates, while Zn(II) sorption occurred mainly by complexation with phenolic groups and precipitation with phosphates. A high correlation (>0.8) between Electrical Conductivity, Cation Exchange Capacity, pH and sorption capacity was identified for all metals tested, highlighting the electrostatic nature of the sorption mechanisms involved. Biochars derived from herbaceous feedstock were better candidates for remediation of soil polluted with Cd(II), Pb(II) and Zn(II), rather than wood-derived biochar. Overall, this study provides evidence of the direct relationship between specific properties of plant-based biochars (pH and EC) and their suitability as adsorbents for some PTEs in soil systems

Biodiversity and systematics of parasitic Crustacea infesting southern African freshwater fishes

Doctor of Philosophy in Science with Zoology, North-West University, Potchefstroom CampusCrustaceans (Arthropoda: Crustacea) are regarded as the most morphologically diverse group in the phylum Arthropoda, and they have the greatest diversity of parasitic forms. Parasitic crustaceans have adapted several morphological and physiological characteristics that enable them to thrive in an array of habitats and hosts. Freshwater parasitic crustaceans are mostly found attached to the external surfaces of their host. These attachment structures are also adapted to the sites of infestation on their hosts. As a result of the pathological impacts of certain parasitic crustaceans on fish, they have been regarded as species of economic and commercial importance. Individuals from the families Argulidae, Ergasilidae, and Lernaeidae are most frequently reported throughout Africa, including both native and invasive parasite species. In southern Africa, however, these reports proved to be limited compared to other regions, therefore suggesting an underrepresentation of the actual diversity of parasitic crustaceans. In addition to scarce distribution records, only a few integrative studies from southern Africa have been carried out on some of these parasites. It was therefore hypothesised that with broader sampling across several localities and hosts in southern Africa, there will be an increased knowledge of the diversity of parasitic crustacean species present in the different river systems as well as new hosts and locality records, in addition to the possible description of new species. More so, the integration of improved morphological techniques and molecular analyses would provide novel information on the morphological characteristics of these species while adding new DNA sequences to the scanty database. In collaboration with the Aquatic Research Group of the University of the Free State, Bloemfontein, as well as several ongoing parasitology projects of the Water Research Group of the North-West University, Potchefstroom, this study aimed at linking distribution data of parasitic crustaceans with morphological and molecular data. Native and exotic fishes belonging to six families (Alestidae, Centrarchidae Cichlidae, Clariidae, Cyprinidae, and Hepsetidae) were collected from several localities in southern Africa. With an integration of morphological (light and scanning electron microscopy) and molecular (partial 18S, 28S, and COI genes) techniques, four native species (Ergasilus mirabilis Oldewage & van As, 1987; Lamproglena clariae Fryer, 1956; Lamproglena hepseti van As & van As, 2007; Lamproglena monodi Capart, 1944), three known invasive species (Argulus japonicus Thiele, 1900; Lernaea cyprinacea Linnaeus 1758; Neoergasilus japonicus (Harada, 1930)), and one new species Neoergasilus sp. nov., were described from the current study. Previous records of Ergasilus mirabilis, a widely distributed species in southern Africa, lacked genetic data. A total of 159 Clarias gariepinus (Burchell, 1822) were caught from various locations in South Africa and Zambia and adult female copepods were collected from two South African localities (Kushokwe Pan and Vaal River) and the Zambezi River in Zambia. Morphological examination confirmed the specimens as E. mirabilis with slight variability in the number of spines and setae from the original description. Molecular analyses included partial ribosomal RNA (18S and 28S) and mitochondrial DNA (COI) genes, providing genetic data to support the morphological characteristics of E. mirabilis. Additionally, new distribution records of E. mirabilis in the Phongolo Floodplain and the Vaal River are reported. The study further reported on species from the genus Lamproglena, which are gill ectoparasites found on African fish hosts in the families Cichlidae, Clariidae, and Hepsetidae. Three Lamproglena species (L. clariae, L. hepseti, and L. monodi) reported from this study are native to southern Africa. Lamproglena clariae is reported for the first time from the Phongolo Floodplain and Nyamiti Pan in South Africa, and from West Lunga in Zambezi. This study also provided genetic data using three genetic markers, which is a notable contribution to the limited molecular data available for Lamproglena species globally. Additional information on the maxillipeds, antennae, and antennules morphology of L. hepseti was also provided. New distribution records as well as the first molecular characterisation of the invasive fish lice Argulus japonicus in Sub-Saharan Africa was also provided from this study. Four fish species: Clarias gariepinus; Cyprinus carpio Linnaeus, 1758; Labeo umbratus (Smith, 1841); Labeobarbus aeneus (Burchell, 1822) were caught from seven different sites along the Orange-Vaal River System and found to be hosts for this argulid. With morphological identification and genetic analysis, parasites collected from these sites were positively identified as A. japonicus. The presence of this invasive species in the Orange-Vaal River System was confirmed and this study further adds to the available knowledge on the distribution of this species, including the addition of a possible new larval stage, and successfully links genetic data for both larval and adult stages to morphology. Lernaea cyprinacea, commonly known as an anchor worm, was also reported from this study. This copepod parasite infests various fish species worldwide and has detrimental effects on fish health. The study provided molecular characterisation of L. cyprinacea from multiple localities in South Africa. This study provided the first record of L. cyprinacea infestation in South Africa on its type host, Cyprinus carpio, Linnaeus, 1758 as well as a new host, Labeobarbus aeneus (Burchell, 1822), within the Orange-Vaal River System. Lernaea cyprinacea was additionally reported for the first time in locations within the Phongolo Floodplain and the Vaal River, and the introduction of this invasive species in the Incomati System was also noted. Lastly, the study reports on two ergasilid species from the genus Neoergasilus: N. japonicus and Neoergasilus sp. nov. Neoergasilus japonicus is an invasive ergasilid with an almost global distribution. In contrast to numerous reports from other continents, the records from southern Africa seem to be from unpublished abstracts and dissertations. This study provides the first integrative study of N. japonicus from Africa and the southern hemisphere and gives the first record of this species from the African tigerfish host, Hydrocynus vittatus Castelnau, 1861. Additionally, the novel Neoergasilus species not previously known to science is described from the sharptooth catfish, C. gariepinus. The integration of morphological identification with genetic data confirms the validity of the sequences generated and provides valuable insights into all parasite groups presented in the current study. The sequences generated for 18S, 28S, and COI are a significant contribution to future parasitic Crustacea studies in southern Africa and across other regions. This study provides an update on the distribution range of these native and invasive parasitic crustaceans in the various river systems sampled, which would serve as a base for future biodiversity and evolutionary studies. As all river systems and host species in southern Africa were not reported on, more robust sampling of other systems and from other host species is recommended for further integrative studies and evolutionary significance of these parasites.Doctora

Cloud Computing and Student’s Record Management Efficiency in Niger Delta University

Information is relatively the life conduit of any organization. An inappropriate management of records and the information contained therein could cost organization both operational and financial fortune. The focus of this paper was to establish the empirical link between cloud computing and student’s record management efficiency in Niger Delta University. Software as a service (Saas) and Platform as a service (Paas) were used to operationalize the predictor variable, while records accessibility and safety were used as measures of record management efficiency. 301 staffers were sampled randomly with questionnaire. Data collected was inferential analyzed using spearman rank order correlation coefficient with the aid of SPSS. Result shows high correlation amongst all variables which means that increase cloud computing practices in the institution would enhance record’s management efficiency. The study recommends therefore that management of Niger Delta University should leverage on available software service provides to store all students’ records on cloud to avoid losses of records due to flood and undue physical environmental conditions. Also, cloud computing model should be utilized for efficiency in record management to create good public image for vantage competitive edge.</jats:p