Effect of Low Dose γ-Irradiation on the Fate and Cell Envelope of Bacillus cereus, Escherichia coli, and Salmonella Typhimurium

Mtenga, Adelard B.,Kassim, Neema,Lee, Won-Gyeong,Heo, Rok-Won,Shim, Won-Bo,Yoon, Yohan,Chung, Duck-Hwa Korean Society for Food Science of Animal Resource 2011 한국축산식품학회지 Vol.31 No.6

This study investigated the effect of low dose ${\gamma}$-irradiation on the damage of the cell envelopes and antibiotic sensitivity profiles of Bacillus cereus, Escherichia coli, and Salmonella Typhimurium. The bacteria suspension in tryptic soy broth was exposed to the ${\gamma}$-irradiation doses of 0, 1, 1.5, 3, and 5 kGy, and then stored at $0^{\circ}C$ for 24 h. A viability test, an antimicrobial sensitivity profile, and an electron microscopy were performed to observe the effects due to ${\gamma}$-irradiation treatment. B. cereus could survive the ${\gamma}$-irradiation up to 5 kGy while E. coli and S. Typhimurium were all deactivated at 1.5 kGy and 5 kGy, respectively. At 5 kGy, the cell count of B. cereus was significantly reduced, and the survived bacteria cells retained their important features. There were no significant changes observed in the antimicrobial sensitivity profile (p>0.05) for the recovered bacteria after irradiation treatment. Low dose ${\gamma}$-irradiation below 3 kGy was found to be insufficient to achieve decontamination of B. cereus and S. Typhimurium. Cell envelope damage and deactivation of different bacteria did not occur in the same manner; thus, deferent doses of ${\gamma}$-irradiation may be required for deactivation of different bacteria.

Resistance of Bacillus cereus and Its Enterotoxin Genes in Ready-to-eat Foods to ${\gamma}$-Irradiation

Mtenga, Adelard B.,Kassim, Neema,Lee, Won-Gyeong,Shim, Won-Bo,Yoon, Yo-Han,Chung, Duck-Hwa 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.2

This study was investigated the resistance of Bacillus cereus ATCC 13752 and its enterotoxin coding genes in cereals, vegetables, and tryptic soy broth to ${\gamma}$-irradiation. Screening for enterotoxin coding genes, viability test, PCR analysis, measurement of DNA concentration, cellular constituents release, SEM, and antibiotic sensitivity tests were performed after irradiation at 0, 1.5, 3, 5, 7, 10, and 15 kGy. Thirty % of strains screened possessed all enterotoxins genes. At 10 kGy B. cereus viable cell count was reduced by 4 logCFU/mL. B. cereus in vegetables and broth demonstrated higher susceptibility than those in cereals. Enterotoxins coding genes could be identified in the ${\gamma}$-irradiated cells, antibiotic sensitivity profile was not affected. Concentration of DNA containing enterotoxin coding genes was reduced and release of cellular constituent was highest at 15 kGy. ${\gamma}$-Irradiation up to 10 kGy did not eliminate B. cereus neither affected their enterotoxins coding genes from ready-to-eat food.

Resistance of Bacillus cereus and Its Enterotoxin Genes in Ready-to-eat Foods to γ-Irradiation

Adelard B. Mtenga,Neema Kassim,이원경,심원보,윤요한,정덕화 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.2

This study was investigated the resistance of Bacillus cereus ATCC 13752 and its enterotoxin coding genes in cereals, vegetables, and tryptic soy broth to γ-irradiation. Screening for enterotoxin coding genes, viability test, PCR analysis, measurement of DNA concentration,cellular constituents release, SEM, and antibiotic sensitivity tests were performed after irradiation at 0, 1.5, 3, 5, 7, 10,and 15 kGy. Thirty % of strains screened possessed all enterotoxins genes. At 10 kGy B. cereus viable cell count was reduced by 4 logCFU/mL. B. cereus in vegetables and broth demonstrated higher susceptibility than those in cereals. Enterotoxins coding genes could be identified in the γ-irradiated cells, antibiotic sensitivity profile was not affected. Concentration of DNA containing enterotoxin coding genes was reduced and release of cellular constituent was highest at 15 kGy. γ-Irradiation up to 10kGy did not eliminate B. cereus neither affected their enterotoxins coding genes from ready-to-eat food.

Effect of Low Dose γ-Irradiation on the Fate and Cell Envelope of Bacillus cereus, Escherichia coli, and Salmonella Typhimurium

Adelard B. Mtenga,Neema Kassim,이원경,허록원,심원보,윤요한,정덕화 한국축산식품학회 2011 한국축산식품학회지 Vol.31 No.6

This study investigated the effect of low dose γ-irradiation on the damage of the cell envelopes and antibiotic sensitivity profiles of Bacillus cereus, Escherichia coli, and Salmonella Typhimurium. The bacteria suspension in tryptic soy broth was exposed to the γ-irradiation doses of 0, 1, 1.5, 3, and 5 kGy, and then stored at 0oC for 24 h. A viability test, an antimicrobial sensitivity profile, and an electron microscopy were performed to observe the effects due to γ-irradiation treatment. B. cereus could survive the γ-irradiation up to 5 kGy while E. coli and S. Typhimurium were all deactivated at 1.5 kGy and 5kGy, respectively. At 5 kGy, the cell count of B. cereus was significantly reduced, and the survived bacteria cells retained their important features. There were no significant changes observed in the antimicrobial sensitivity profile (p>0.05) for the recovered bacteria after irradiation treatment. Low dose γ-irradiation below 3 kGy was found to be insufficient to achieve decontamination of B. cereus and S. Typhimurium. Cell envelope damage and deactivation of different bacteria did not occur in the same manner; thus, deferent doses of γ-irradiation may be required for deactivation of different bacteria.

Efficiency of Fractionated γ-Irradiation Doses to Eliminate Vegetative Cells and Spores of Bacillus cereus from Raw Rice

Adelard B. Mtenga,Neema Kassim,심원보,정덕화 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.2

Efficacy of fractionated γ-irradiation to eliminate vegetative and spore forms of Bacillus cereus from raw rice was studied. Viable bacteria and spores count performed after irradiation treatment revealed that vegetative cells and spores (7.9 and 7.7 log CFU/g) of B. cereus in raw rice tolerated γ-irradiation up to 10 and 20 kGy, respectively and were eliminated at 15 and 25 kGy respectively on single treatment. Exactly 2 times of 5 kGy irradiation treatment eliminated all vegetative B. cereus (7.9 log CFU/g). A treatment with fractionated doses of γ-irradiation effectively eliminated vegetative bacteria but not spores of B. cereus. Field emission SEM images revealed the damage by γ-irradiation to the spore exosporium. This study suggests new approach of using fractionated doses of γ-irradiation to eliminate foodborne pathogens in food which are affected by high doses of γ-irradiation.

Preliminary Evaluation of Slaughter Value and Carcass Composition of Indigenous Sheep and Goats from Traditional Production System in Tanzania

Shija, Dismas S.,Mtenga, Louis A.,Kimambo, Abiliza E.,Laswai, Germana H.,Mushi, Daniel E.,Mgheni, Dynes M.,Mwilawa, Angello J.,Shirima, Eligy J.M.,Safari, John G. Asian Australasian Association of Animal Productio 2013 Animal Bioscience Vol.26 No.1

The aim of the pilot study was to evaluate slaughter characteristics and carcass composition of indigenous long fat tailed sheep and Small East African goats purchased from the auction markets slaughtered at 1.5 to 2 yrs of age and 20 kg to 25 kg live weight. The animals were slaughtered according to halal standard procedures. The left half carcasses were jointed into eight wholesale joints, and dissected into muscles, fat and bone, which were weighed separately. Sheep had greater (p<0.05) slaughter BW (22.29 kg vs 20.50 kg) and empty BW (20.17 kg vs 18.67 kg) than goats (p<0.05). Dressing percentages were lower (p<0.001) in sheep than goats when carcass weight was expressed as percentage of slaughter BW (42.31% and 47.15%) and empty BW (46.75% and 51.79%). Sheep carcasses had lower (p<0.001) proportion (66.18% vs 71.64%) of muscles and higher (p<0.001) proportion of fat (7.41% vs 3.44%) than goat carcasses. Sheep had proportionally lighter (p<0.001) shoulder (18.89% vs 22.68%) and heavier (p<0.05) proportion of chump (7.916% vs 6.76%) and main rib (8.12% vs 7.07%). Sheep had more (p<0.001) muscles in the leg (28.83% vs 27.08%) and main rib (7.62% vs 6.36%) than goats. Sheep had less (p<0.001) muscles (20.28% vs 23.56%) in shoulder joints when expressed as percentage of total muscle of carcasses. It is concluded that there are differences in sheep and goat both in terms of carcass and joint yields and composition. The present study also implies that there is need to consider setting different meat cuts and prices for these cuts when one takes into account the differences in muscle distribution within joints in sheep and goats.

The In Vitro and In Vivo Efficacy of Hen IgY Against Vibrio parahaemolyticus and Vibrio vulnificus

( Kassim Neema ),( Adelard B Mtenga ),( Won Bo Shim ),( Duck Hwa Chung ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.10

The inhibitory effect of IgY against Vibrio parahaemolyticus and Vibrio vulnificus responsible for seafood-borne diseases was investigated in this study. Water-soluble fractions (WSF) of protein containing IgYs were isolated from the egg yolk of hens initially immunized with formalininactivated V. parahaemolyticus or V. vulnificus. Protein, total and specific IgY contents of the WSF were determined. The inhibitory and protective effects of IgYs on the growth of V. parahaemolyticus and V. vulnificus were assayed in liquid medium and in mice. IgYs showed high affinity to their corresponding antigens with high titer from day 28 onwards. Protein contents and total IgY concentrations remained stable throughout the immunization period, whereas specific IgY concentrations increased steadily and reached a plateau at day 49. Specific IgY powder (150 mg/ml) significantly inhibited further multiplication of both V. parahaemolyticus and V. vulnificus in liquid medium as compared with the control IgY. The bacteria count in mice feces was lower in mice pretreated with specific IgYs than in those pretreated with PBS or control IgY. Higher survival of mice was observed in the experimental groups pretreated with either anti-V. parahaemolyticus (75% survival) or anti-V. vulnificus (87% survival) IgYs, compared with those in the control groups pretreated with PBS or nonspecific IgY. All mice in the control groups died within three days after bacteria inoculation; hence, the protective effect of specific IgYs against infection caused by V. parahaemolyticus and V. vulnificus was demonstrated.

Production of Coturnix Quail Immunoglobulins Y (IgYs) against Vibrio parahaemolyticus and Vibrio vulnificus

Neema Kassim,Adelard B. Mtenga,이원경,김정숙,심원보,정덕화 한국식품과학회 2011 Food Science and Biotechnology Vol.20 No.6

Production of chicken immunoglobulins Y (IgYs) and their applications in prophylactic, therapeutic,detection of microbial contaminants and as a diagnostic tool has been widely studied with limited information from other avians. This study produced Coturnix quail (Coturnix coturnix japonica) egg yolk IgYs against Vibrio parahaemolyticus and Vibrio vulnificus. Formalin inactivated (FIVP, FIVV, mixed FI-VP/VV) and heat inactivated (HIVP, HIVV, mixed HI-VP/VV) Vibrio immunogens (109 CFU/mL) were intramuscularly immunized into quail through thigh muscles. Egg yolk IgY was purified by water dilution-ammonium sulfate precipitation method and the activity was determined by enzyme-linked immunosorbent assay (ELISA). Formalin inactivated immunogens induced high humoral immune response for both V. parahaemolyticus and V. vulnificus over heat inactivated immunogens. However, IgYs resulted from HIVP and FIVV immunogens, showed high specificity to V. parahaemolyticus and V. vulnificus respectively. Detection limits of the indirect ELISA using the produced IgYs were 105 CFU/mL for V. parahaemolyticus and 106CFU/mL for V. vulnificus. The developed antibodies showed high binding affinity to their corresponding immunogens, very little cross reactivity to Staphylococcus aureus and not other bacteria strains (p<0.05), a phenomenon which was also observed in Western blot.

Production of Mouse Anti-Quail IgY and Subsequent Labeling with Horseradish Peroxidase Using Cyanuric Chloride

( Kassim Neema ),( Adelard B Mtenga ),( Won Bo Shim ),( Duck Hwa Chung ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.4

Polyclonal antibodies labeled with a tracer have been commonly used as secondary antibodies in immunochemical assays to quantify the concentration of antibody-antigen complexes. The majority of these antibodies conjugated with a tracer are commercially available, with the exception of few untouched targets. This study focused on the production and application of mouse anti-quail IgY as an intermediate antibody to link between quail egg yolk IgY and goat anti-mouse IgG-HRP as primary and secondary antibodies, respectively. Subsequently, the produced mouse anti-quail IgY was labeled with horseradish peroxidase (HRP) and its efficiency on enzyme linked immunosorbent assay (ELISA) was compared with that of commercial rabbit anti-chicken IgY-HRP. As an intermediate antibody, mouse anti-quail IgY was successfully produced with good affinity and sensitivity (1:10,000) to the primary and secondary antibodies. Subsequently, mouse anti-quail IgY was effectively conjugated with HRP enzyme, resulting in a secondary antibody with good sensitivity (1:10,000) to quail anti-V. parahaemolyticus and V. vulnificus IgY. The detection limit was 105 CFU/ml for both V. parahaemolyticus and V. vulnificus. The efficiency of the produced conjugate to detect quail IgY on ELISA was comparable to that of the commercial rabbit anti-chicken IgY-HRP, and hence the produced and labeled mouse anti-quail IgY-HRP can be used as a secondary antibody to detect any antibody produced in quail.

Meat Quality Characteristics of Small East African Goats and Norwegian Crosses Finished under Small Scale Farming Conditions

Hozza, W.A.,Mtenga, L.A.,Kifaro, G.C.,Shija, D.S.N.,Mushi, D.E.,Safari, J.G.,Shirima, E.J.M. Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.12

The aim of the experiment was to study the effect of feeding system on meat quality characteristics of Small East African (SEA) goats and their crosses with Norwegian ($SEA{\times}N$) goats finished under small scale farming conditions. Twenty four castrated goats at the age of 18 months with live body weight of $16.7{\pm}0.54kg$ from each breed (SEA and $SEA{\times}N$) were distributed in a completely randomized design in a $2{\times}3$ factorial arrangement (two breed, and three dietary treatments). The dietary treatments were; no access to concentrate (T0), 66% access to ad libitum concentrate allowance (T66) and 100% access to ad libitum concentrate allowance with 20% refusal (T100) and the experimental period was for 84 days. In addition, all goats were allowed to graze for 2 hours daily and later fed grass hay on ad libitum basis. Daily feed intakes were recorded for all 84-days of experiment after which the animals were slaughtered. Feed intake of T100 animals was 536 g/d, which was 183 g/d higher than that of T66 group. Supplemented goats had significantly (p<0.05) better feed conversion efficiency. The SEA had higher (p<0.05) hot carcass weight (8.2 vs 7.9 kg), true dressing percentage (54.5 vs 53.3) and commercial dressing percentage (43.3 vs 41.6) compared to $SEA{\times}N$. There was no significant difference (p>0.05) for dressing percentage and carcass conformation among supplemented goats except fatness score, total fat depots and carcass fat which increased (p<0.05) with increasing concentrate levels in the diet. Increasing level of concentrate on offer increased meat dry matter with subsequent increase of fat in the meat. Muscle pH of goats fed concentrate declined rapidly and reached below 6 at 6 h post-mortem but temperature remained at $28^{\circ}C$. Cooking loss and meat tenderness improved (p<0.05) and thawing loss increased (p<0.05) with ageing period. Similarly, meat tenderness improved (p<0.05) with concentrate supplementation. Shear force of muscles varied from 36 to 66, the high values been associated with Semimembranosus and Gluteobiceps muscles. The present study demonstrates that there are differences in meat quality characteristics of meat from SEA goats and their crosses with Norwegian breeds finished under small scale farming conditions in rural areas. Therefore, concentrate supplementation of goats of both breeds improves meat quality attributes.