Browsing by Author "Shikongo-Nambambi, Martha N."

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    Control of bacterial contamination during marine fish processing
    (Macrothink Institute, 2012) Shikongo-Nambambi, Martha N.; Shoolongela, Abrahams S.; Schneider, Martin B.
    Fish is a vital source of nutrients to humans due to its proteinaceous nature, high content of unsaturated fatty acids and low contents of carbohydrates. In their natural environments fish are exposed to a myriad of microorganisms some of which compromise the shelf life of the product and/or safety in humans. Most fish factories located along coasts find it economical to use processed sea water during processing. Processed sea water however can be a source of microbial contamination to fish. Fish factories are also vulnerable to biofilm formation on surfaces and within water distribution pipes. Biofilms result from bacterial attachment and growth in aqueous environments that render bacteria resistant to sanitising agents. This article reviews the conditions permissible to bacterial contamination in marine fish factories. The role of water in bacterial contamination and survival has been highlighted. Bacterial pathogens commonly associated with fish factories and their survival strategies have also been discussed. The use of selected sanitizing agents and UV irradiation in marine fish processing have been explored. The fundamental antimicrobial mechanisms of chlorine, ozone and H2O2 is the generation of toxic metabolic intermediates that damage microbial structural and functional components, causing metabolic paralysis and cell death. UV radiation damages DNA hindering gene expression processes. Controlling bacteria biofilm has been well experimented in fresh water systems, but knowledge about disinfection of marine waters is still lacking. The review concludes that in order to optimise the microbiological quality of marine fish, suitable disinfectants effective in sea water need to be authenticated.
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    Coping with Climate Change Challenges by Feeding Indigenous Chickens under Intensive Systems in Namibia
    (OMICS Group, 2012) Petrus, Ndilokelwa P.; Mpofu, I.; Shikongo-Nambambi, Martha N.
    Floods that have hit Northern Communal Areas (NCAs) of Namibia in recent year pose feeding and other challenges to indigenous chicken. Indigenous chickens constitute a major source of livelihoods among rural farmers. The objective of this study was to determine the potential of intensive feeding of high and low plane of protein nutrition to indigenous chickens as one way of coping with environmental challenges caused by annual floods in the NCAs. Adequacy of protein inclusion in the diet is a viable option for improving the growth of small rural owned chickens. Two hundred and four indigenous chickens were subjected to two levels of plane of nutrition namely high and low plane of protein nutrition. At the low level, the protein was 18% in the 1-8 week age group, 16% in 9-22 week age group and 12% in the 23-36 week age. Feeding at high plane of protein nutrition was as follows; 23% in the 0-8 week age group, 20% in the 9-22 week age group and 16% in the 23-36 week age group. The control group was fed according to the Namibian poultry industry standards. The results showed significant and highest responses between the treatments in weeks 1-8 of age. Between 9-22 weeks, chicken mortality lowest at 5.6% in the high plane of nutrition group compared to 14.4% in the low plane of nutrition. The birds in control group consumed significantly (P<0.05) less feed than those fed with the high and low protein diet. Intensive feeding has a potential of alleviating nutritional stress of indigenous chickens under adverse environmental conditions. Farmers however, have to respond by cropping more intensively for the feed resources to be available.
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    Identification of putative vibrio species isolated from processed marine fish using Thiosulphate-Citrate-Bile-Sucrose (TCBS), Agar
    (School Domain International, 2012) Shikongo-Nambambi, Martha N.; Chimwamurombe, Percy M.; Venter, Stephanus N.
    Aims: To identify putative Vibrio isolates obtained from processed hake, pilchards and horse mackerel using Thiosulphate-Citrate-Bile-Sucrose (TCBS) agar.Place and Duration of Study: Sampling during April – June 2005 in Walvis Bay Namibia. Further analyses performed at the Department of Microbiology and Plant Pathology, University of Pretoria, South Africa between 2005 and 2007. Methodology: The 247 putative Vibrio isolates obtained from Thiosulphate-Citrate-Bile- Sucrose (TCBS) agar were initially grouped according to their Gram, oxidase and oxidation-fermentation reactions. Thereafter PCR was used to screen the isolates for genes specific to human pathogenic Vibrio species such as Vibrio cholerae, Vibrio parahaemolyticus and Vibrio vulnificus. This was followed by sequencing the 16S rRNAgene for isolates of interest and drawing Neighbour Joining phylogenetic trees based on the data. All atypical isolates were further characterised by a combination of selected phenotypic tests and the V. alginolyticus specific collagenase gene PCR. Results: Of the 247 isolates obtained from TCBS, four were Gram positive. Many of the Gram negative isolates belonged to the family Enterobacteriaceae and others were members of the Pseudomonadaceae. Of the 91 isolates identified as belonging to the Vibrionaceae and related families, Vibrio alginolyticus was the dominant Vibrio species. None of the bacteria isolated from the processed fish belonged to the human pathogenic Vibrio species. Conclusion: This study again demonstrated that TCBS agar is not selective for the isolation of Vibrio species and that a wide range of bacteria could be isolated on this medium when analysing marine fish. The identity of putative Vibrio isolates obtained from this medium should therefore be confirmed employing a number of phenotypic and genetic techniques to accurately identify the atypical isolates.
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    The role, isolation and identification of Vibrio species on the quality and safety of seafood
    (Academic Journals, 2012) Shikongo-Nambambi, Martha N.; Petrus, Ndilokelwa P.; Schneider, Martin B.
    Seafoods in their natural environments are associated with a variety of microorganisms. Fish shelf life reduction results from microbial metabolism, mainly by Gram negative bacteria that produce chemical compounds responsible for bad odour, texture and taste. Shelflife is estimated by performing total viable bacterial counts at ambient and refrigeration temperatures. The type and number of bacteria present on seafood depends on the microbial composition of the surrounding waters, on the intrinsic factors, extrinsic factors, processing, and implicit factors and on the microbial interactions within the fish itself. Although, sea food safety assessment is preferably determined by detecting indicator organisms; such as Enterobacteriaceae and coliforms, none of these groups fulfil all requirements that guarantee food safety necessitating direct detecting of relevant pathogens. Vibrio species are part of the bacteria genera associated with seafoods borne diseases. Prompt and accurate detection and identification methods of pathogens are imperative to determine the product compliance with seafood microbiological criteria. Although cultural methods have long been used in detecting human pathogens including Vibrio species in fish, these methods are time consuming and sometimes inaccurate. Also some pathogens have the propensity to change into the Viable but non culturable (VBNC) state in unfavourable environments. The use of molecular methods is hampered by drawbacks, such as inter species 16S rRNA sequence similarity and that some strains carry multiple copies of the 16S rRNA gene. A combination of classical, numerical taxonomy and Multi locus sequence analysis (MLSA) methods are promising to give absolute resolution between closely related Vibrio species.
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    Value addition and processed products of three indigenous fruits in Namibia
    (2013) Cheikhyoussef, Ahmad; Bille, P.G.; Shikongo-Nambambi, Martha N.;
    The objectives of this study were to add value to three popular indigenous fruits found in Namibia namely, Marula (Sclerocarya birrea), Monkey orange (Strychnos cocculoides) and Eembe (Berchemia discolour) into processed food products and to train rural communities on value addition for job creation, income generation and food security. Indigenous fruits are receiving increasing interests from researchers and scholars because of their nutrition and abundance in most African countries. The fruits are important sources of food for rural communities especially at times of food shortage, hunger and other disasters. In addition, they provide enormous health benefits such as antioxidants, vitamins and minerals. They are also known to create jobs and generate income for rural communities. Because of their role in combating food insecurity, nutrition and the problems of seasonality, studies on their value addition were carried out in Namibia. Different types of food products were made from the fruits namely; juice, jam, jelly and muffins (cakes). A pilot study was carried out to determine the levels and preference range of ingredients in the mix to formulate recipes of the products prior to processing and training the community members. The results were subjected to paired preference tests and the best ratio was then used. According to consumer preference test, marula juice was on the lower value (2.3) due to its low pH (3.26). As for jam and jelly; quality, taste and colour were acceptable and preferred. The three products made from monkey orange were all preferred but those from eembe were downgraded (2.31-3.20) due to dark colour and lack of flavour. The microbiological quality of the produced products confirmed their safety characteristics. The products made in this study were shown to be viable, of good quality and good sources of income for rural communities. The fruit flavour from marula and monkey orange can be utilized in the dairy and other soft drink industries for making yoghurts, sour milk, ice cream, juices and jams.