Bangladesh Journal of Microbiology

Clostridium perfringens: Sporulation, Spore Resistance and Germination

2015-08-31T13:00:49+06:00

Clostridium perfringens are Gram-positive, endospore-forming, anaerobic bacteria with the ability to cause enteric diseases both in human and domesticated animals. As one of the leading cause of food-borne illness in the United States, certain C. perfringens type A isolates exert their action through the production of C. perfringens enterotoxin (CPE), which is expressed only during spore formation. In addition, C. perfringens spores are highly resistant to heat and other environmental factors. Since genome sequences of three C. perfringens strains have been annotated and made public, efforts have been made towards understanding the initiation of sporulation and identifying the key differences between Clostridium and Bacillus sporulation phosphorelay. Small, acid soluble spore proteins (SASPs) have been shown to be required for resistance of C. perfringens spores to heat. Work is also underway to identify nutrient signals required for C. perfringens spore germination.

Performance of Arbuscular Mycorrhiza Inoculated Acacia mangium Seedlings on Degraded Land with Different Rates of Phosphorus

2015-08-31T13:00:49+06:00

The experiment was conducted in the degraded ex-tin mining farm of Universiti Putra Malaysia during November 1998 to May 1999. The experiment was laid out in split plot design with three replications. Three phosphorus (P) rates, viz., 0, 50 and 100 g Gaphsa phosphate rock (GPR) per plant in combination with and without arbuscular mycorrhiza (AM) inoculation were studied on newly planted tree species Acacia mangium. Mycorrhiza inoculation was assigned to the main plot and P dose to the subplot. Three-month-old AM preinoculated seedlings were planted in the field at 2 m x 2 m spacing. The experiment was continued until 160 days after planting (DAP). Mycorrhiza inoculation and rate of P application significantly influenced growth and development of the A. mangium plants. The highest growth of un-inoculated A. mangium plants was observed with 100 g GPR per plant; whereas for AM inoculated plants the highest growth was observed with 50 g GPR per plant. This indicates that P requirement of newly planted A. mangium plants on degraded ex-tin mining land could be reduced to 50 g GPR per plant, i.e., by 50% with AM inoculation.

Multiple-Antibiotic Resistance Mediated by Plasmids and Integrons in Uropathogenic Escherichia coli and Klebsiella pneumoniae

2015-08-31T13:00:49+06:00

Antibiotic resistance in urinary tract infection (UTI) is a growing public health problem in the world. In this study, a total of 182 uropathogens were isolated from patients with symptoms of urinary tract infection (UTI). Escherichia coli (88%) was the most prevalent isolate, while Klebsiella pneumoniae was recovered from 12% cases. The male/female ratio was 1:3. About 56% female and 51% male patients belonged to the age group >40 years. The antibiotic resistance rates of the isolates to fifteen different drugs were investigated. E. coli and K. pneumoniae showed variable pattern of susceptibility. The percentage of resistance to different drugs was higher in E. coli isolates compared to that of K. pneumoniae. Among the total number of isolates about 87% were resistant to at least three commonly used antibiotics. All the isolates were sensitive to imipenem. Analysis of the plasmid DNA had shown that the plasmid pattern was very diverse in both E. coli and K. pneumoniae. All the isolates contained multiple numbers of plasmid ranging from 1.0 to >140 MDa. Middleranged plasmids (30 to 80 MDa), the transferable resistance plasmids, were found to be present in 86% E. coli and 85% K. pneumoniae isolates. The strong association observed between plasmid profiles and drug resistance patterns suggest that plasmids other than the common plasmids may have epidemiological significance. The presence of class 1 and class 2 integrons were also investigated. A relatively high occurrence of class 1 integrons, that are associated with lateral transfer of antibacterial resistance genes, was observed in K. pneumoniae (88%) than in E. coli isolates (54%). Class 2 integrons were not found in any of the E. coli and K. pneumoniae isolates. These results show the high rate of drug resistance and the presence of high rate of transferable elements in these MDR isolates.

Detection, Antimicrobial Susceptibility and Serotyping of Streptococcus pneumoniae from Cerebrospinal Fluid Specimens from Suspected Meningitis Patients

2015-08-31T13:00:49+06:00

Pneumococcal meningitis is the most important cause of community-acquired meningitis in children resulting in high morbidity and mortality worldwide. This study aimed to evaluate immunochromatographic test (ICT), a rapid detection method, for pneumococci in cerebrospinal fluid (CSF) and also to assess antibiotic susceptibility pattern of the clinical isolates. The findings of CSF-ICT of suspected meningitis cases were also compared with the results of CSF culture, latex agglutination test (LAT) and polymerase chain reaction (PCR). Among these diagnostic methods, ICT and PCR showed 100% specificity. A total of 401 CSF specimens were cultured but culture positivity was observed with 55 (13.7%) cases in which Streptococcus pneumoniae was identified from 20 (36.4%) culture-positive cases. A remarkably high resistance rate to gentamicin (95%) and cotrimoxazole (60%) among the invasive strains of S. pneumoniae was observed, while none of the isolates exhibited resistance to penicillin, ceftriaxone and chloramphenicol by disk diffusion test. Minimum inhibitory concentration (MIC) showed similar susceptibility pattern. The invasive strains (n = 18) belonged to 9 different serotypes including 1, 2, 4, 34, 12A, 38, 19F, 35A and 45. The prevalent serotypes were 2 (23.5%), 1 (17.6%) and 45 (11.8%). The study shows that a remarkable proportion of meningitis cases in children are caused by S. pneumoniae. Diagnostic methods like ICT and PCR can be considered as effective methods for the detection of pneumococcal meningitis even with the patients who have been treated with empirical antibiotics. Ceftriaxone is a safe choice for empirical therapy, while the use of cotrimoxazole for the treatment of meningitis infections is debatable.

Assessment of Arbuscular Mycorrhizal Association in Some Fruit Plants in Bangladesh

2015-08-31T13:00:49+06:00

Â Rhizosphere soils of 19 fruit plants from horticultural farm of Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur were assessed for arbuscular mycorrhiza (AM) spore population and determining colonization in their roots. The spore numbers recorded ranged from 48.0 (Citrus limon) to 1,050 (Annona reticulata) per 100 g soil in 2004, 41.0 (Citrus grandis) to 916.7 (Phyllanthus emblica) in 2005 and 44.3 (Citrus grandis) to 575.0 (Syzygium samarangense, white) in 2006. A considerable variation was observed in average spore numbers recorded in three consecutive years. Different fruit plants showed different percentages of root colonization by AM fungi. Among all the fruit plants, the highest colonization (86.7%) was found in Syzygium jambos and Elaeocarpus floribundus and the lowest colonization (20.0%) was recorded in Syzygium samarangense (red).

Evaluation of Multiplex PCR System for Simultaneous Detection of Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis in Shrimp Samples

2015-08-31T13:00:49+06:00

A multiplex polymerase chain reaction (PCR) method was evaluated for simultaneous detection of Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis in shrimp samples. The sensitivity of DNA amplification by PCR in this method was found to be 103 cfu/ml for each pathogen. When this protocol was adopted for the detection of each of the above mentioned pathogen in spiked shrimp extract culture, similar sensitivity was observed. However, this method detected 1 bacterial cell for E. coli O157:H7 and S. enteritidis and 100 for L. monocytogenes per 25 g spiked shrimp samples after overnight enrichment. In the commercially imported shrimp samples, none was found to contain any of the three pathogens by multiplex PCR or by conventional method, which suggests that the multiplex PCR is a reliable and useful for rapid screening of shrimp samples for E. coli O157:H7, L. monocytogenes and S. enteritidis. This will save time and increase our ability to assure food safety.

A Longitudinal Study to Identify the Causes of Mortality in Fayoumi and Rhode Island Red Chickens and the Immune Status of the Birds against Newcastle Disease

2015-08-31T13:00:49+06:00

With a prospective longitudinal study undertaken between November 2005 and July 2006 survival rates and disease status of Fayoumi and Rhode Island Red (RIR) chickens, reared at a government poultry farm, Pahartali Zonal Poultry Farm (PZPF), were assessed. Immune status of these chickens against Newcastle disease (ND) was also determined by estimating the haemagglutination inhibition (HI) titre to Newcastle disease virus (NDV) in blood sera of the chickens. The results showed that, at the end of the 37 week, the survival rate of the Fayoumi and RIR chickens were 87 and 81% respectively. The difference of the survival rates between the two groups was significant (p <0.05). Among the diseases, coccidiosis was the predominant disease affecting both the populations. The incidence rate of coccidiosis, coccidiosis plus enteritis, salmonellosis, colibacillosis and heat stroke in Fayoumi and RIR chickens was 0.095 and 0.135, 0.064 and 0.057, 0.007 and 0.010, 0.006 and 0.012, and 0.017 and 0.016 respectively. The HI titre dynamics showed that, in case of Fayoumi (except 1st month), HI titre was always >log2 6.4, which was well above the protective threshold. Like Fayoumi, the highest level of HI titre (>log2 6.9) to NDV in the RIR chickens was recorded in the same month and almost identical ranges of HI titres to NDV were recorded in both Fayoumi and RIR chickens throughout the study period.

Optimization of Medium Ingredients for Keratinolytic Protease Production by Bacillus licheniformis MZK-03 using Statistical Experimental Designs

2015-08-31T13:00:49+06:00

A culture medium was optimized for the production of keratinolytic protease by a newly isolated strain of Bacillus licheniformis MZK-03 in shake-flask culture. Based on the results of preliminary experiments, feather mill, molasses and trace elements were found to be major variables in keratinolytic protease production. The concentrations of these ingredients were optimized by using two statistical approaches, namely Box-Wilson method and central composite design. The optimized culture medium, finally determined by using the statistical approaches, composed of 0.95% feather mill, 0.12% molasses and 1.44% trace elements. The keratinolytic protease production was increased by approximately 2-fold when the strain was grown in the optimized medium (95.2 U/ml) compared to the un-optimized medium (56.05 U/ml).

Production and Characterization of Keratinolytic Protease of Bacillus licheniformis MZK-03 Grown on Feather Mill

2015-08-31T13:00:49+06:00

Keratinolytic protease is an inducible specific proteolytic enzyme, which is produced by Bacillus licheniformis MZK-03 in presence of keratin (feather mill) as sole carbon and nitrogen source in growth medium. Maximum level of keratinolytic protease was produced after 42 h at 37°C over a wide range of initial pH (5.0 to 12.0) under continuous agitation (200 rpm). Keratinolytic protease worked best at 37°C and at pH 8.5. The enzyme was quite stable over a wide range of pH (7.0 to 11.0) but activity dropped drastically beyond this level (enzyme activity dropped to 8.8% and 19.3% at pH 6.5 and 12.0, respectively). Half-life of keratinolytic protease at 70° and 60°C were found to be 3 and 7 min respectively. The enzyme showed highest stability at 40°C (>90% after 3 h). The half-life at 4°C was 34 days. The presence of metal ions (5 mM) like Mg²⁺, Mn²⁺, Ca²⁺ and K⁺ had no remarkable effect on the keratinolytic protease activity but the activity decreased in presence of Hg²⁺ and Cu²⁺. The enzyme may belong to serine protease group as it is inhibited by serine protease inhibitor phenyl methyl sulphonyl fluoride (PMSF). The enzyme is as compatible as other commercially available enzymes used in leather industry with tannery chemicals. It was completely incompatible with Na₂S and CaO for their high alkalinity (pH >13.0), which was also observed for other commercial enzymes except the commercial enzyme supplemented with ammonium sulphate.

Impacts of Mycoplasma gallisepticum Vaccine on Newcastle Disease Vaccination and Protection in Parent Stock Flocks

2015-08-31T13:00:49+06:00

The present study reports on the impact of Mycoplasma gallisepticum (MG) vaccination on vaccine respond and subsequent protection against Newcastle disease (ND) in parent stock flocks of Department of Livestock Services (DLS) using MG killed vaccine and conventional ND vaccines. Birds were grouped into four groups, each consisted of 50 birds from the same flock. Group A birds were vaccinated with ND, group B with ND and MG, group C with MG, and group D birds were kept as unvaccinated control. The parameters studied included detection of ND antibody, MG seroprevalance, mortality (%), and cause of death. The sera of groups B and C were sero-positive after administration of MG vaccine. The haemagglutination-inhibition (HI) titres of group A were higher than group B from week 4 after administration of MG vaccine to the birds of group B. The mortality was very low; one bird of group C died at week 5 due to traumatic injury and another bird of group D died at week 2 due to infectious bronchitis virus (IBV). After challenge, birds of groups A and B showed no clinical signs and normal post mortem findings were found. Birds of groups C and D showed clinical signs from day 3 and different pathological lesions were found in post mortem. The MG vaccination did not improve other parameters. Therefore, inoculation of MG INAC vaccine is not justified and is too expensive at farm levels.

Isolation and Identification of Indigenous Bakers' Yeast

2015-08-31T13:00:49+06:00

This investigation was performed to isolate and identify indigenous bakers' yeast. Initially, 75 yeast isolates were collected from different sources such as decomposed fruits, fermented rice and fermented fruit juices. Twenty five isolates were selected by primary screening; among them, ten isolates were considered as potential bakers' yeasts on the basis of their ability to produce high amount of biomass and leavening action. Two isolates were identified as Saccharomyces cerevisiae, seven as Saccharomyces species and only one as Kluyveromyces species. These isolates have sufficient potential to be produced commercially after evaluation of some baking parameters like texture and organoleptic properties.

Effect of Nutrients and Cellobiose Octaacetate on Cellulolytic Enzyme Productions by Streptomyces albolongus

2015-08-31T13:00:49+06:00

The cellulolytic mesophilic isolate Streptomyces albolongus (A5) was used to determine the effect of nitrogen and carbon sources on the production of cellulolytic enzymes using cellobiose octaacetate (COA) as an inducer. The isolate was able to degrade various cellulosic carbon sources. However, the rate of degradation, production of extracellular protein, reducing sugar, saccharification and production of enzyme were enhanced when 0.6% COA was used as an inducer in addition to the main substrate. Among the nitrogen sources tested, beef extract showed maximum production of the enzyme (136.7 U/ml CMCase) in Winstead's medium. The enzyme production was further enhanced in the medium supplemented with 0.6% COA, which corresponded to 154.69 U/ml CMCase activity. Among the carbon sources, carboxymethylcellulose (CMC) was found to be the best carbon source and again supplementation of the medium with 0.6% COA enhances CMCase production. Other than CMCase activity, the organism also produced appreciable levels of filter paper cellulase (FPase), avicelase and Ã¢-glucosidase activities.

Antimicrobial Activity of Crude Extract Obtained from the Root of Plumbago zeylanica

2015-08-31T13:00:49+06:00

Ethanolic extract of Plumbago zeylanica root was investigated for its antimicrobial activities against 11 human pathogenic bacteria and 6 phytopathogenic fungi using disc diffusion method and poisoned food technique respectively. The extract exhibited good antibacterial and antifungal activities against the test organisms. Among the test bacteria, Vibrio cholerae was found to be the most sensitive to the extract showing the highest diameter of zone of inhibition and lowest minimum inhibitory concentration (MIC) value (200 Î¼g/ml). The extract was also very effective against Escherichia coli and Pseudomonas aeruginosa showing MIC value of 250 Î¼g/ml. Among the phytopathogenic fungi tested, Curvularia lunata exhibited the highest sensitivity to the extract with an MIC value of 150 Î¼g/ml, which was followed next by Colletotrichum corchori and Fusarium equiseti (MIC value 250 Î¼g/ml). The root extract from P. zeylanica seems promising since it showed both antibacterial and antifungal activities.

Antifungal Activity of Forty Higher Plants against Phytopathogenic Fungi

2015-08-31T13:00:49+06:00

Ethanolic extract of 40 higher plants representing 23 families were tested for antifungal activity against some phytopathogenic fungi. The two most active plants showing potent antifungal activity were Acorus calamus and Piper betel. The rhizome extract of A. calamus exhibited highest antifungal activity inhibiting the mycelial growth completely (100%) against all the 6 test pathogens. P. betel exhibited more than 50% inhibition against most of the test fungi. The ethanolic extract of several higher plants could be used as alternative source of antifungal agents for protection of plants or crops against fungal infection.

Isolation of Keratinophilic Fungi from Soil in Khairpur City, Sindh, Pakistan

2015-08-31T13:00:49+06:00

One hundred and twenty five soil samples were collected from five areas in the vicinity of Khairpur city, Sindh, Pakistan and screened for the presence of keratinophilic fungi by using hair bait technique. A total 253 isolates belonged to eight genera and eleven species of keratinophilic fungi were recovered. Maximum number (153/253, 60.5%) of keratinophilic fungi was recovered from farm land and poultry soils. Aspergillus niger was most prevalent species and represented 20.2% of the total number isolated. A. flavus and A. fumigatus were almost equal in their prevalence and represented 11.9 and 11.1%, respectively. Botrytis cinaria comes next constituting 9.9%; followed by Mucor spp. (9.1%) and Chochliobolus lunatus (8.3%). Other species isolated less frequently included Chrysosporum asperatum (5.9%), Fusarium spp. (5.1%), Penicillium spp. (3.1%) and A. wentii (2.4%). The distribution pattern of the different keratinophilic fungi and their significance are discussed.