Browsing by Author "Mdegela, Robinson"
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Item Antimicrobial susceptibility of flavobacteriaceae isolates from nile tilapia (oreochromis niloticus) in Tanzania(African Journal of Microbiology Research, 2020) Mwega, Elisa; Chengula, Augustino; Colquhoun, Duncan; Mutoloki, Stephen; Mdegela, Robinson; Evensen, Øystein; Wasteson, YngvildThis study aimed to assess antimicrobial susceptibility of members of the family Flavobacteriaceae isolated from Nile tilapia (Oreochromis niloticus). Antimicrobial susceptibility of 67 Flavobacteriaceae isolates originating mainly from ponds and Lake Victoria against 19 antimicrobial agents was determined by the broth micro dilution method. Overall, most isolates were susceptible to enrofloxacin (97%; MIC 90 2 μg/ml) followed by novobiocin (85%, MIC 90, 4 μg/ml) and the aminoglycoside streptomycin (85%; MIC 90 , 128 μg/ml). Some isolates were also susceptible towards trimethoprim/sulfamethoxazole (77.6%), neomycin and florfenicol both at 62.7%. Susceptibility levels were low for tylosin tartrate (32.8%), clindamycin and sulphathiazole both at (23.9%), ceftiofur (6%), spectinomycin (6%) and tetracyclines/oxtetracyclines (4.5%). In contrast, β-Lactams (amoxicillin, penicillin), gentamycin and erythromycin exhibited very poor activity against Flavobacteriaceae isolates. The extent of antimicrobial susceptibility did not vary significantly among isolates from farmed and wild fish isolates (P > 0.01). The highest Multiple Antimicrobial Resistance (MAR) index was observed in Chryseobacterium indologenes (0.89) and the lowest in Chaetoderma indicum isolates (0.32). Our results indicate that most of Flavobacteriaceae isolates are multidrug resistance, and this may be associated with intrinsic resistance mechanisms to a broad range of antimicrobial agents. However, the need remains to carryout in-depth study to understand better the underlying genetic mechanisms given that the magnitude and trend for susceptibility was comparable between isolates from aquaculture and fisheries. The findings from this study give us insight into appropriate choice of antimicrobial agents for effective treatment of infections caused by these isolates.Item Changes in fatty acids during storage of artisanal-processed freshwater sardines (Rastrineobola argentea)(WILEY, 2023) Chaula, Davis; Jacobsen, Charlotte; Laswai, Henry S.; Chove, Bernard Elias; Dalsgaard, Anders; Mdegela, Robinson; Hyldig, GretheFor ages, indigenous small fish species have been important in food and nutritional security of poor communities in low income countries. Freshwater fish, in particu- lar fatty fish species are attracting a great attention because they are good sources of health promoting long chain omega-3 fatty acids. Docosahexaenoic acid (DHA, C22:6n-3), Docosapentaenoic acid (DPA, C22:5n-3) and eicosapentaenoic acid (EPA, C20:5n-3) are the main omega-3 PUFAs known to confer health benefits in humans if consumed in required amounts. While nutritionally valued, omega-3 PUFAs in fish are susceptible to oxidative damage during processing, transportation and subsequent storage. Lake Victoria sardines (Rastrineobola argentea), are rich source of chemically unstable omega-3 fatty acids DHA, DPA and EPA. Traditionally, sardines are pre- served by sun drying, deep frying and smoking. Sardine products are transported, stored and marketed at ambient temperatures. Generally, uncontrolled and higher temperatures are known to increase vulnerability of polyunsaturated fatty acids to oxidation which in turn results into loss of nutritional and sensory qualities. This study investigated changes of fat acids in sun dried, deep fried and smoked sardines during storage. Lipolysis and the progressive hydroperoxides formation were monitored by free fatty acids (FFAs) and peroxide value (PV) respectively. None volatile secondary products of lipid oxidation were measured by thiobabituric acid reactive substances (TBARS). Fatty acids were analyzed by gas chromatography with a flameionization de- tector (GC-FID). Deep fried sardines maintained the lowest and apparently stable PV, TBARS and FFAs. Proportions of saturated fatty acids and polyunsaturated fatty acids decreased with time while that of monounsaturated fatty acids increased. Omega-3 fatty acids EPA, DPA and DHA decreased with increase in storage time. In 21 days of storage, DHA was oxidized beyond detectable levels in all sardine products. Gradual increase in FFAs in sun dried sardines was suggestive of lipid hydrolysis induced by enzymes.Item Effect of clove (Syzygium aromaticum) and seaweed (Kappaphycus alvarezii) water extracts pretreatment on lipid oxidation in sun‐dried sardines (Rastrineobola argentea) from Lake Victoria, Tanzania(Food Science & Nutrition published by Wiley Periodicals, Inc., 2019) Chaula, Davis; Laswai, Henry; Chove, Bernard; Dalsgaard, Anders; Mdegela, Robinson; Jacobsen, Charlotte; Hyldig, GretheSmall indigenous fish species play a significant role in food and nutritional security of poor communities in developing countries. Sardines (Rastrineobola argentea) are fish species of Lake Victoria known to be a good source of health‐promoting omega‐3 fatty acids. Open sun drying is a common and traditional sardine processing and preservation method. Sun‐dried products suffer from characteristic off‐flavor due to lipid oxidation which discourage product consumption and limit diversification. This study investigated the use of clove (Syzygium aromaticum) and seaweed (Kappaphycus alvarezii) water extracts as natural antioxidants to impede lipid oxidation in sun‐dried sardines. Lipid oxidation was assessed by peroxide value, volatile secondary oxida- tion products, and fatty acid profiles. The antioxidant capacity of extracts was evalu- ated by total phenolic content, 1, 1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, and iron (Fe 2+ ) chelating ability. Results showed that 5, 10, and 20 g/L clove extracts significantly reduced peroxidation in sun‐dried sardines by 38.7%, 54.6%, and 56%, respectively. Clove extracts resulted in higher retention of omega‐3 fatty acids and lower concentrations of secondary lipid oxidation products as op- posed to seaweed counterpart. This research has demonstrated feasibility of pre- treating whole, omega‐3‐rich small sardines with natural antioxidants to avert lipid oxidation during sun drying.Item Ethnobotanical study of medicinal plants used to manage HIV/AIDS opportunistic infections in Rungwe, Mbeya region, Tanzania(Academic Journal, 2018) Kibonde, Suma F.; Augustino, Suzana; Mabiki, Faith P.; Mdegela, RobinsonThe current ethnobotanical study identified medicinal plant species used to manage HIV/AIDS opportunistic infections by the communities in Rungwe District, Tanzania. Data were collected using questionnaires (n=193), interviews (n=9) and field observations. A total of 31 plant species from 23 families are used in managing HIV/AIDS opportunistic infections. Compositae and Rosaceae were predominantly used in disease management by 15% each. Of the plant parts, leaves were the most used (44%), followed by roots (28%), bark (7%), fruits, seeds and stem (5%) while the least used plant parts were tubers (4%) and the whole (2%). Tuberculosis utilized 60% of the species, Herpes simplex 55%, chronic diarrhea 40%, oral candidiasis 35% and Herpes zoster 30%. Dissotis phaeotricha scored the highest fidelity value (73%), followed by Berberis holstii (60%). The knowledge on medicinal plants among respondents was influenced by; informal education (p<0.01), village location (p<0.01) and ethnic background (p<0.05). The study exposed the presence of reasonable knowledge of traditional medicinal plants among communities in Rungwe District. The results contribute to the conservation of experimental experiential knowledge of medicinal plants used in the management of HIV/AIDS opportunistic infections hence, shouldering world’s efforts geared towards anti-HIV/AIDS innovations.Item Evaluation of the gill filament-based EROD assay in African sharptooth catfish (Clarias gariepinus) as a monitoring tool for waterborne PAH-type contaminants(Springer, 2005-05-15) Mdegela, Robinson; Myburgh, Jan; Correia, Dacia; Braathen, Marte; Ejobi, Francis; Botha, Christo; Sandvik, Morten; Skaare, Janneche UtneThe ability of African sharptooth catfish (Clarias gariepinus) in inducing cytochrome P-450 class 1A (CYP1A) and glutathione S-transferase (GST) biomarkers was determined in liver and gill filaments after 4 days of waterborne exposure to the polycyclic aromatic hydrocarbon, benzo[a]pyrene (B[a]P). Male (n=6) and female (n=6) fish were exposed to B[a]P added to the water (30 lg/l) corresponding to 5 mg/kg total body weight. Five female and six male fish, exposed to acetone alone added to the water served as controls. The 7-ethoxyresurufin-O-deethylase (EROD) activity was measured in hepatic microsomes and gill filaments. In addition, GST activity was determined in the hepatic cytosolic fraction and fluorescent aromatic compounds (FACs) in bile and biliverdin. Benzo[a]pyrene strongly induced EROD activities in gill filaments of both sex. Levels of FACs per ml of bile were 17-fold higher in exposed fish compared to the controls. Correlations between induction of EROD activities in gill filaments and liver and between induction of EROD activities in gill filaments and levels of biliary FACs metabolites were strong. GST activities in the hepatic cytosolic fraction were similar amongst the treated and control groups. This is the first report on studies determining EROD activities in gill filaments and hepatic tissue, FACs in bile and GST in hepatic tissues of C. gariepinus after waterborne exposure to B[a]P. The findings suggest that the gill filament-based EROD assay in C. gariepinus can be used to monitor the pollution of AhR agonists in aquatic ecosystems in eastern and southern African countries.Item Fatty acid profiles and lipid oxidation status of sun dried, deep fried, and smoked sardine (Rastrineobola argentea) from Lake Victoria, Tanzania(Taylor & Francis, 2019) Chaula, Davis; Laswai, Henry; Chove, Bernard; Dalsgaard, Anders; Mdegela, Robinson; Hyldig, GretheFreshwater fishes contain long chain omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) of highest nutritional value. PUFAs in fish are susceptible to oxidative damage during processing and subsequent storage. Sardines (Rastrineobola argentea) are an important fish species of Lake Victoria, constitut- ing 72.3% of the total landings by weight on the Tanzanian side of the lake. Fatty acid profiles and lipid oxidation status of sun-dried, deep-fried, and smoked sardines were investigated. Lipid oxidation was assessed by peroxide value, thiobarbituric acid reactive substances (TBARS), and free fatty acids. Fatty acids were analyzed by gas chromatography with flame ionization detector. The three omega-3 PUFAs: docosahexaenoic acid (C22:6n-3), docosapentaenoic acid (C22:5n-3), and eicosapentaenoic acid (C20: 5n-3) contributed 57–60, 63, and 38% of PUFAs in sun-dried, smoked, and deep-fried sardines, respectively. Lipid oxidation reactions were more pronounced in sardines dried on sand and rocks, with TBARS values 97.87 and 84.18 μmolMDA/kg, respectively. The polyene index was significantly lower (p < 0.05) in deep-fried sardines, indicating lower retention of PUFAs in the product. Lake Victoria sardines are a rich source of omega-3 PUFAs. PUFAs in sun-dried sardines are prone to oxidative damage. Smoking resulted in relatively higher retention of omega-3 fatty acids in products.Item Isolation and identification of long -chain aliphatic compounds from synadenium glaucescens(The Journal of Phytopharmacology, 2022) Nyigo, Vitus A; Malebo, Hamisi M; Mabiki, Faith; Mdegela, RobinsonPurification of dichloromethane extract from root barks and leaves of Synadenium glaucescens extracts through chromatographic techniques resulted into the isolation of two compounds, namely erythrinacinate C and 1-octacosanol. Chemical structures were established mainly using both one and two dimensional 1H and 13C NMR data and by comparison of the current NMR data with those from literature. Mass spectrophotometry data were used for confirmation through molecular ion peak. Both compounds are known to have been isolated from other plant species but are being reported from this plant species for the first time.Item Natural antioxidants from clove for protecting omega-3 fatty acids in sardines (Rastrineobola argentea) during deep frying process.(Sokoine University of Agriculture, 2019-04-11) Chaula, Davis; Jacobsen, Charlotte; Laswai, Henry; Chove, Bernard; Dalsgaard, Anders; Mdegela, Robinson; Hyldig, GretheSardines (Rastrineobola argentea), popularly known as “dagaa” is one of the leading commercial fish species of Lake Victoria. The fatty fish species are attracting great attention because they are good source of omega-3 polyunsaturated fatty acids which are vital for a wide range of biological functions and are implicated in the prevention of numerous diseases. While nutritionally valued omega-3 fatty acids are highly susceptible to oxidation during fish processing due to their unsaturated nature. Oxidation reactions result in loss of omega-3 fatty acids and production of undesired off-flavours which discourage consumption and limit diversification of sardine products.Synthetic antioxidants may be used to prevent lipid oxidation but have been claimed to be carcinogenic at higher levels. The replacement of synthetic antioxidants with ones of natural origin is now in demand. In this study, natural antioxidants rich extracts from clove buds were applied on sardines in a bid to impede lipid oxidation during deep frying process. Lipid oxidation was assessed by peroxide value (PV), volatile compounds and fatty acid profiles using Gas chromatograph (GC-MS and GC-FID).The results showed that natural antioxidants from clove buds reduced peroxidation and protected highly unsaturated omega-3 fatty acids from oxidation during deep frying process. Total polyunsaturated fatty acids amounted 7.30 % in pre-treated deep fried sardines.Retention of omega-3 fatty acids was 0.70 % more in pre-treated than untreated fish. Significantly lower amounts of representative volatile compounds were produced in sardines pre-treated with clove extracts. The study demonstrated feasibility to pre-treat sardines with natural antioxidants for protecting omega-3 fatty acids against oxidation during deep frying.Item Protection against oxidation of Omega-3 Fatty Acids with natural antioxidants in clove (szygium aromaticum) water extracts during storage of sun dried sardines (Ratrineobola Argentea)(Fortune Journals, 2019) Chaula, Davis; Jacobsen, Charlotte; Laswai, Henry; Chove, Bernard; Dalsgaard, Anders; Mdegela, Robinson; Hyldig, GretheOmega-3 fatty acids are a family of polyunsaturated fatty acids (PUFAs) with beneficial health effects to humans if consumed in required amounts. Fatty fish species are known to be rich in marine-based omega-3 fatty acids, eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, C22:6n-3) and docosapentaenoic acid (DPA, C22:5n-3). Sardines (Rastrineobola argentea) from Lake Victoria are a good source of health promoting omega-3 fatty acids. Open sun drying is a common and traditional sardine processing and preservation method. Due to their chemical instability omega-3 fatty acids in sun dried sardines are prone to lipid oxidation during processing and subsequent storage. This study investigated the use of clove (Syzygium aromaticum) water extracts as natural antioxidants to protect omega-3 fatty acids against oxidative damage during storage of sun dried sardines. Lipid oxidation was assessed by peroxide value, volatile secondary oxidation products and fatty acid profiles. The antioxidant capacity of extracts was evaluated by total phenolic content, 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and iron (Fe 2+ ) chelating ability. Clove extracts resulted into significantly higher retention of total PUFAs, DHA, EPA and DPA at the end of 30 days storage period and lower concentrations of secondary lipid oxidation products. This is an evidence of their enhanced oxidative stability in the real food system due to presence of natural clove antioxidants.