This journal is a peer reviewed scientific forum for the latest advancements in bacteriology research on a wide range of topics including food safety, food microbiology, gut microbiology, biofuels, bioremediation, environmental microbiology, fermentation, probiotics, and veterinary microbiology. Because of our open access digital publication model, we believe that Agriculture, Food and Analytical Bacteriology will have a major and immediate impact on advancing scientific research that will only increase as the journal grows.
current issue
Volume 1 Issue 2
Published November 2011
Articles in this issue
Influence of Winter and Summer Hutch Coverings on Fecal Shedding of Pathogenic Bacteria in Dairy Calves
Published 11/2011
Volume 1 Issue 2
Pp. 98-104Keywords: Dairy calves, E. coli, Hutch covering, Salmonella
Abstract:
The effects of hutch coverings utilized during the summer and winter months to moderate extreme temperatures were examined on fecal prevalence of E. coli O157:H7 and Salmonella in newborn dairy calves. In the initial study, the effects of shade using screens in three treatment groups: no shade, partial shade, and full shade were examined. Two additional studies were designed where individual calf hutches were modified with a hutch blanket (treatment) or no hutch blanket (control) in the winter study and a ventilated hutch design added as a third treatment in the summer study. During the summer experiment, prevalence of E. coli O157:H7 and Salmonella was low; however, Salmonella was increased (P < 0.05) in the ventilated hutch versus the control treatment. In the winter study, quantifiable results for both E. coli O157:H7 and Salmonella were largely negative. Salmonella positive samples were numerically higher, however no treatment differences were observed. In the shade cloth study all fecal samples were E. coli O157:H7 negative. Salmonella was cultured from all treatment groups, however no differences were observed between treatments. Summarily, there is no evidence that hutch treatments decreased the period prevalence of fecal shedding of Salmonella, E. coli O157:H7 or Enterococcus.
quick look full article download pdftoggle
Production of Cyclosporin A by Static Fermentation Using Tolypocladium inflatum MTCC 557
Published 11/2011
Volume 1 Issue 2
Pp. 105-115Keywords: amino acids, cyclosporin A, Fermentation, production, response surface method, static, stationary culture, Tolypocladium inflatum
Abstract:
The effect of different nutrients (carbon and nitrogen sources) and fermentation factors (such as inocu- lum size and volume of production media) was evaluated on the production of Cyclosporin A (CyA) in sta- tionary culture of Tolypocladium inflatum MTCC 557 over a 21-day period at 25oC. Glycerol was found to be the best carbon source and gave a maximum CyA production of 410 mg/L. Further, response surface meth- odology was used to optimize the concentrations of medium components which took the CyA production to 452 mg/L. The exogenous supplementation of various amino acids individually and in combination was also studied. The time of addition of the optimized combination of amino acids was also evaluated. A maximum CyA production of 1241 mg/L was obtained when L-valine and L-leucine were added after 4th day of the fermentation. The optimum concentrations of media components were (in g/L) glycerol 98.8, casein peptone 28.5, malt extract 20, peptone 10 and α-amino butyric acid 5.7.
quick look full article download pdftoggle
Comparative Studies on the Survival of Verocytotoxigenic Escherichia coli and Salmonella in Different Farm Environments
Published 11/2011
Volume 1 Issue 2
Pp. 116-122Keywords: feces, persistence, Salmonella Dublin, Salmonella Typhimurium, slurry, soil, Verocytotoxigenic E. coli, water
Abstract:
The aim of this study was to investigate the survival characteristics of verocytotoxigenic Escherichia coli (VTEC) and Salmonella in soil, slurry, farm water and bovine feces. Samples of each of the aforementioned media were inoculated with separate cocktails of VTEC and Salmonella and stored at 4 and 14 ºC, representing average Winter and Summer temperatures respectively. Samples were withdrawn periodically and surviving cells enumerated by directly plating onto selective media. Decimal reduction times (D-values) were calculated from the inverse of the slope obtained by linear regression of a plot of time versus the log of surviving cells. In the latter stages of the experiment, presence or absence was determined by enrichment and selective plating. VTEC and Salmonella D-values ranged from 3.59 to 23.84 days. Temperature significantly affected VTEC survival in water (P<0.05) and Salmonella survival in bovine feces (P<0.01) but not in any of the other farm media tested. In general there was no significant difference (P>0.001) between VTEC and Salmonella survival in a given medium under similar storage temperatures. However, Salmonella D-values were signiZcantly higher in slurry (4°C) and bovine feces (4°C and 14°C). This study provides critical comparative data on VTEC and Salmonella death rates in a range of environments commonly encountered on farms to support the development of quantitative microbial risk assessment (QMRA) and provide the scientiZc basis for an effective good agricultural practice (GAP) food safety program.
quick look full article download pdftoggle
A Transcriptomic Expression Array, PCR and Disk Diffusion Analysis of Antimicrobial Resistance Genes in Multidrug-Resistant Bacteria
Published 11/2011
Volume 1 Issue 2
Pp. 123-139Keywords: Antimicrobial, disk diffusion, hybridization, microarray, oligonucleotide, PCR, resistance genes
Abstract:
We report the development of a microarray-based transcriptomic expression analysis method for the detection of 131 antimicrobial resistance genes in multidrug-resistant clinical (Enterococcus faecium, E. faecalis), aquaculture (Aeromonas veronii), poultry (Campylobacter jejuni, Staphylococcus aureus), and out break (Salmonella enterica serovar Typhimurium) strains.Unmodified oligonucleotide probes and 131 pair of primers for the genes conferring resistance to 22 different antimicrobials were used for transcriptomic array and PCR analysis. Detection of resistance genes by transcriptomic array and PCR methods correlated well with the susceptibility profiles of the isolates used in the study. However, some of the genes conferring resistance to ampicillin (amp), bleomycin (ble), lincomycin (linAn2, lmr, lmrA, lmrB, mgt), neomycin (neo, nptII, himaR), oleandomycin (oleB, oleC-orf4, oleC-orf5), penicillin (mecA), and rifampin (arr2) could not be detected by above methods. Co- or cross-resistance to these drugs and their extracellular transport due to the presence of 2 to 5 efflux pump genes (oleB, marA, tetA, tetB, vraD) is believed to confer resistance to the above antimicrobials. Moreover, the presence of resistance genes for bacitracin, chloramphenicol, erythromycin, kanamycin, streptomycin, and tetracycline in phenotypically sensitive isolates indicated either inactive versions of these genes or modulation of gene expression. Overall, the transcriptomic array method provided a valuable insight into the mechanism(s) of resistance, status of gene expression at transcription level, and detection of all the antimicrobial resistance genes among bacteria from different ecological sources.
quick look full article download pdftoggle
Antibiotic Resistance and Plasmid Profiles in Bacteria Isolated from Market Fresh Vegetables
Published 11/2011
Volume 1 Issue 2
Pp. 140-149Keywords: antibiotic resistant bacteria, fresh vegetables, Isolation, plasmid profile
Abstract:
This study was carried out to evaluate the total bacterial load and to isolate and identify antibiotic resistant bacteria in fresh vegetables sold in the local markets of Dhaka city and also to determine its resistance pattern to antibiotics. The highest Aerobic Plate Count (APC) found in tomato and carrot samples of local markets were 5.17 log10 colony forming units (CFU/g) (Annanda Bazar Market) and 5.78 log10 CFU/g (Khilgaon Market), respectively. However, the lowest APC found in tomato and carrot samples of local markets were 4.90 log10 CFU/g (Malibagh Bazar) and 5.50 log10 CFU/g (Malibagh Market), respectively. Antibiotic sensitivity patterns of the isolates were determined and nearly all of them were resistant to commonly used antibiotics. The percentage of resistant bacteria to the total load was also high. Amoxicillin resistant bacteria counts were 3.4%, followed by ce[xime 2.15%, and ciprofloxacin count at 1.61%. There were 0.26% of the bacteria found to be multi drug resistant. Therefore, the fresh vegetables samples collected from local markets were heavily contaminated with resistant bacteria and are of special concern for human consumption. Plasmid pro[le, curing and transformation study results demonstrated that resistance to amoxicillin is plasmid mediated but for cefixime and ciprofloxacin were not. These study results demonstrated that plasmids are one of the important ways to spread resistance but chromosomal mutation by environmental selection might also responsible for resistance.
quick look full article download pdftoggle
Impact of Calcium Chloride Dip and Temperature on Microbial Quality of Organically and Conventionally Grown Melons
Published 11/2011
Volume 1 Issue 2
Pp. 150-158Keywords: aerobic bacteria, calcium chloride, Enterobacteriaceae, food safety, melons, organic production, post-harvest storage, storage temperature
Abstract:
Melons (Cucumis melo L.) have been associated with many foodborne illness outbreaks. Current melon handling recommendations do not require cool temperature storage to maintain the safety of whole mel- ons, yet storage temperature often in[uences microbial growth. While calcium chloride (CaCl2) dips have been shown to reduce post harvest decay and increase shelf-life of many different fruits, the anti-microbial effect is unknown. It is also unclear whether production method (organic or conventional) impacts micro- bial growth on fresh produce. This study evaluated the impact of a 20 min 0.08 M CaCl2 post-harvest dip treatment and two storage temperatures (10˚C and 21˚C) on total aerobic and Enterobacteriaceae bacterial counts present on the surface of organically and conventionally grown melons (cultivar ‘Arava’) stored for 10 d. Storage temperature signiXcantly impacted microbial growth, as higher levels of aerobic and Entero- bacteriaceae bacteria grew overall on melons stored at 21˚C vs. 10˚C (p<0.05). Storage time did not impact bacterial counts within the 10 d. Organic melons had overall more aerobic growth than conventional melons (p<0.05), with non-dipped organic melons stored at 21˚C having the highest aerobic bacterial counts. Organic melons treated with CaCl2 and stored at 21˚C had lower (p<0.05) Enterobacteriaceae levels than non-dipped organic melons stored at 21˚C. Based on the results of this study, storing whole 'Arava' melons at cooler temperatures is best to slow microbial growth, and the use of a CaCl2 dip treatment may be a useful method to minimize growth on organic melons.
quick look full article download pdftoggle
Minimizing the Risk of Listeria monocytogenes in Retail Delis by Developing Employee Focused, Cost Effective Training
Published 11/2011
Volume 1 Issue 2
Pp. 159-174Keywords: delicatessen, Listeria monocytogenes, Worker training
Abstract:
Listeria monocytogenes is the one of most lethal of all food pathogens.It has a high fatality rate among immune compromised individuals and has been shown to contaminate ready-to-eat (RTE) deli meats, which have been linked to several outbreaks of listeriosis. Unfortunately, the incidence of listeriosis has not decreased signiXcantly since 2001 and the 2010 Healthy People goal of 2.4 cases of listeriosis per million consumers has not been met. More than 8 out of 10 of the listeriosis cases linked to delis were attributed to RTE luncheon meats sliced in retail stores, which has led risk assessors to suggest that cross-contamination from the retail deli environment is likely responsible forthe stubborn resistance in reducing listeriosis. Research has also shown that most food borne illnesses result from food handler error, which may be minimized when employees are properly trained and transfer their training to their jobs.There is a need for training that is speciXcally focused on the deli employee which could have a measurable impact in decreasing the risk of L. monocytogenes cross-contamination. Proper motivation and training of employees and managers is vital to keep consumers safe. Thus, there is a crucial need to Xll gaps in the knowledge base for designing effective training for newly hired and hard-to-reach employees in a retail food service environment.
quick look full article download pdftoggle
Survival of Salmonella in Organic and Conventional Broiler Feed as Affected by Temperature and Water Activity
Published 11/2011
Volume 1 Issue 2
Pp. 175-185Keywords: conventional poultry feed, organic poultry feed, Salmonella, storage temperature, water activity
Abstract:
The objective of this study was to compare the ability of Salmonella to survive in organic and conventional broiler feeds as affected by temperature (11, 25, and 38°C), water activity (aw 0.75, 0.55, and 0.43) and storage time (up to 80 days). Feeds were inoculated with a mixture of \ve Salmonella serotypes at high and low populations (6 and 3 log CFU/g, respectively), and populations and presence (by enrichment) were monitored over time.Although the number of Salmonella in organic feed for the majority of temperature-by-aw combinations was significantly lower (P ≤ 0.05) compared to the number in conventional feed over the 80-day storage period, differences in mean populations were less than 1 log CFU/g.The odds-ratio (OR) for presence of Salmonella was significantly higher (P ≤ 0.05) in conventional feed than in organic feed containing high and low inocula (OR = 4.76 and 2.92, respectively). Based on these findings, we generally conclude that there were no biologically significant differences in survival of Salmonella in organic and conventional poultry feeds.
quick look full article download pdftoggle
Isolation and Initial Characterization of Plasmids in an Acetogenic Ruminal Isolate
Published 11/2011
Volume 1 Issue 2
Pp. 186-192Keywords: acetogens, bacteria, characterization, genetics, Isolation, plasmids, rumen
Abstract:
Two of nine acetogenic ruminal isolates screened for plasmids were found to contain plasmid DNA. Five plasmids ranging in size from 4.5 to 32 kilobase pairs (kb) were observed in isolate H3HH while a single 35 kb plasmid was observed in isolate H4. The smallest of the plasmids from isolate H3HH, estimated at 4.5 kb, was isolated using gel electrophoresis followed by electroelution. Of the 13 restriction endonucleases tested, this plasmid was cut once by EcoRV, SinI and HindIII and cut twice BglII. The physiological functions of the individual plasmids are unknown. However, a plasmid-free derivative (H3HP) of isolate H3HH displayed increased sensitivity to several antibiotics.
quick look full article download pdftoggle