Open Access Original Research Article

Biochemical and Molecular Characterization of Bacterial Wilt Disease of Banana and Evaluation of their Antibiotic Sensitivity

Zannati Ferdous Zaoti, S. M. Zia Hasan, Md. Firose Hossain, Md. Faruk Hasan, Md. Asadul Islam, Md. Khalekuzzaman, Biswanath Sikdar

Microbiology Research Journal International, Page 1-10
DOI: 10.9734/MRJI/2017/38206

Aims: Isolation and characterization of bacteria from the bacterial wilt disease of banana and evaluation of their sensitivity.

Study Design:  This study was an experimental laboratory design.

Place and Duration of Study: Disease infected banana plant leaves were collected from Rajshahi University Campus, Rajshahi, Bangladesh in 2015 and the experiment had been conducted from 2015 to 2016. 

Methodology: Two bacterial colonies were isolated (W1 and W2) and characterized by some morphological, biochemical and molecular test. Antibiotic sensitivity pattern was determined by disc diffusion method against the isolated bacteria. Molecular analysis were observed through the amplification of 16s ribosomal RNA primers and hrp gene specific primers (BXW-1/RST65 and BXW-3/RST69) and were cross reacted with other pathovars of Xanthomonas campestris, including Xcampestris pv. musacearum strains.

Results: Isolated both two bacterial colonies (W1 and W2) were rod-shape, gram negative and motile, but W1 was yellow and W2 was creamy in color. Biochemical tests showed that both of them were catalase positive with addition to isolate W1 was MacConkey, citrate and TSI positive and SIM and urease negative whereas isolate W2 was MacConkey, citrate and urease positive, and SIM and TSI negative. In antibiotic sensitivity test among the five antibiotic (chloramphenicol, gentamycin, erythromycin, penicillin and ciprofloxacin), isolate W1 showed the highest susceptibility to penicillin and isolate W2 at gentamycin. In the molecular analysis, DNA from the isolated bacteria W1 showed approximately 1650bp band by using the 16s ribosomal primers 27-F and 1391-R. The presence of DNA sequence related to the hrp genes were successfully amplified by the isolate W1 which was related to X. campestris pv. musacearum.

Conclusion: As there is no effective research work on bacterial wilt disease of banana in Bangladesh, this work will be helpful for further direction of this devastating disease management.

Open Access Original Research Article

Farnesol Anti-biofilm Activity against Candida albicans Reference and Mutant Strains

Adriana da Fonte Porto Carreiro, Sarah Florindo de Figueiredo Guedes, Beatriz Helena Dias Panariello, Paula Ventura da Silveira, Malvin N. Janal, Simone Duarte

Microbiology Research Journal International, Page 1-7
DOI: 10.9734/MRJI/2017/39345

Introduction: Farnesol is known as a quorum sensing (QS) molecule that has a role as an anti-biofilm agent. It is produced by C. albicans and blocks the morphological transition from yeasts to hyphae. The hyphal development is important for the formation of substantial biofilm biomass. Mutant strains lacking the filamentation genes EFG1 and TEC1 are less virulent than their reference strains.

Aims: To determine the role of the transcription factors EFG1 and TEC1 by using knockout strains (Δ/Δ efg1 and Δ/Δ tec 1) on farnesol’s mechanism of action regarding dry weight and colony count of Candida albicansbiofilms.

Study Design: tt-farnesol solutions at a concentration of 12.5 mM were prepared. Biofilms (n=6) of the strains C. albicans SN 425 (reference strain), C. albicans CJN 2330 (Δ/Δ tec1) and C. albicans CJN 2302 (Δ/Δ efg1) were treated twice daily with tt-farnesol or a vehicle control for 1 min during biofilm formation (48 h). Biofilms were also treated with 0.2% chlorhexidine (1 min) as a positive control and 0.89% NaCl (1 min) as a negative control. After treatments, biofilms were evaluated by dry weight (μg) and colony forming units per milliliters (CFU/mL).

Results: Data were analyzed by two-way ANOVA and post-hoc t-tests (α=0.05). Relative to the control, farnesol significantly reduced the CFU/mL of all the C. albicans strains and the biomass of the mutant strain CJN 2330.

Conclusion: Twice daily treatment with tt-farnesol at a concentration of 12.5 mM exhibited anti-biofilm activity against C. albicans. Analysis of strain differences suggests that the presence of the transcription factor TEC1 protects the biofilm against tt-farnesol mechanism of action.

Open Access Original Research Article

Isolation and Characterization of Some Hydrocarbon Utilizing Bacteria Isolated from Contaminated Soil in Zuma, Bwari Area Council, Fct, Abuja, Nigeria

T. O. Ozoude, E. U. Eleanya, N. S. Uzoaru, N. F. Okey-Ndeche

Microbiology Research Journal International, Page 1-8
DOI: 10.9734/MRJI/2017/34158

The wide spread use of petroleum products leads to contamination of soil and aquatic environments, thereby posing a serious threat to all life forms including humans. Therefore, isolation of oil-degrading microorganisms and optimizing conditions for biodegradation process are important. Thus, this study was aimed at isolating and characterizing hydrocarbon utilizing bacteria from hydrocarbon contaminated soil in Bwari area council, Federal Capital Territory, Abuja, Nigeria, using three different petroleum products (petrol, kerosene and diesel) thereby checking their catabolic capacities on the products. Enrichment culture technique (using mineral salt medium; MSA) was employed to obtain fourteen (14) bacterial isolates capable of utilizing the petroleum products. The ability to degrade petroleum hydrocarbons is not restricted to a few microbial genera; a diverse group of bacteria and fungi have been shown to have this ability. The most important (based on frequency of isolation) genera of hydrocarbon utilizers in environments were Pseudomons spp. 21.43%, Bacillus spp. 21.43%, Acinetobacter spp. 7.14%, Corynebacterium spp. 7.14%, Staphylococci spp. 7.14%, Citobacter spp. 14.29%, Aeromonas spp. 14.29%, Flavobacterium spp. 7.14%. The hydrocarbon utilizing bacteria count ranged from 1.8 ×10to 1.5 ×10cfu/ml showing a high range of different bacteria found in polluted soil due to formation of consortia to degrade the substrates. The highest growth was found in petrol sample (PS) followed by kerosene sample (KS) and then diesel sample (DS), implying the ability of these organisms to rapidly utilize lower molecular and low density hydrocarbon than higher ones. Applications of this adaptation of microorganisms have been seen in bioremediation, oil recovery, indicators of environmental pollution of petroleum hydrocarbons, etc which are all environmental friendly and cost effective.

Open Access Original Research Article

DNA Microarray-based Identification of Fungal Pathogens in Neutropenic Patients in Alexandria University Hospitals in a Twelve-month Interval

Dalia El-Sayed Metwally, Abeer Abdel Rahim Ghazal, Nadia Ali Sdek, Shady Hassan Fadel, Yasmeen Abd El Raouf Arafat

Microbiology Research Journal International, Page 1-11
DOI: 10.9734/MRJI/2017/39249

Background: Systemic fungal infections are increasing, and they cause severe morbidity and high mortality rates among immuno-compromised patients. Conventional laboratory methods for identifying fungal pathogens, although continuously improving, are still time consuming. Therefore, they are usually inadequate for ensuring early targeted therapy, especially for uncommon or newly identified fungal species. Molecular detection and identification using polymerase chain reaction for the amplification of fungal DNA is being applied more frequently for the early diagnosis and identification of fungal pathogens.

Materials and Methods: The current study included 31 neutropenic cancer patients who had fever, who were not responding to antibiotics and who attended the outpatient clinics or were inpatients in the Haematology Department of the Medical Research Institute hospital and Oncology Department of Alexandria Main University hospital during a 12-month period. Blood samples were collected from each patient for the diagnosis of invasive fungal infections (IFIs) by conventional blood culture and DNA microarray.

Results: Out Of the 24 neutropenic cancer patients tested by conventional blood culture, fungal growth was detected in 2 (8.3%) blood cultures (both for Candida albicans), and the blood cultures for the remaining cases were negative. Through DNA microarray, three patients (9.7%) were found to have no fungal infections, two (6.5%) with one fungal infection, six (19.4%) with infection with two fungal species and 20 (64.5%) with infection with more than two fungal species.

Conclusion: The present oligonucleotide array system allowed the rapid and reliable identification of a vast number of fungal pathogens. Advanced diagnostic methods may have led to an overall higher sensitivity of diagnosing IFI, but the actual incidence of IFI may not have changed.

Open Access Original Research Article

Change in Antibiotic Susceptibility Pattern of Clinical Bacterial Isolates from Two Hospitals in Dhaka, Bangladesh over a Period of Three Years

Mahnaz Hossain Fariba, Abdullah Bashar Sami, Debanjan Bhattacharjee, Sajal Kumar Saha, Sitesh Chandra Bachar, M. Aftab Uddin, Ruhul Haque Kuddus

Microbiology Research Journal International, Page 1-10
DOI: 10.9734/MRJI/2017/39626

Introduction: It is established that improper use of antibiotics leads to rapid development of bacterial antibiotic resistance. We investigated changes in the antibiotic susceptibility pattern of pathogenic bacteria in a megacity where improper antibiotic use is common.

Methodology: Data on the antibiotic susceptibility pattern of clinical isolates to 28 commonly used antibiotics was obtained from two hospitals at time point A (Jan-Dec 2009, or Nov-Dec 2010) and at about 12-36 months later (time point B), and the data were compared using the one-sided test for equality of proportions. For large samples, tests using Z-score and normal distribution were conducted; for small samples, Fisher’s exact test was performed.

Results: Of the 194 different pairs of isolate clusters compared; 66.5% of the cluster-pairs showed no change in the antibiotic susceptibility pattern. Of the remaining 33.5% of the isolate clusters, the time point B clusters showed a significant decrease in antibiotic susceptibility in 21.1% of the cases, and a significantly higher susceptibility in 12.4% of the cases, compared to the corresponding time point A clusters. The decreased antibiotic susceptibility was observed in 20.0% of the Gram-negative and 24.1% of the Gram-positive bacterial isolate clusters; and the increased antibiotic susceptibility was observed in 10.0% of Gram-negative and 18.5% of Gram-positive bacterial clusters.

Conclusions: Antibiotic resistance and susceptibility of Gram-positive and Gram-negative pathogenic bacteria may significantly change over a period as short as 1-3 years. Continuous vigilance of such changes in a region may allow development of regional strategies for rational antibiotic use.