Open Access Original Research Article

Exploring the Optimization of UV Mutants of Streptomyces clavuligerus for Clavulanic Acid Production

Isara Lourdes Cruz-Hernández, Eliton da Silva Vasconcelos, Juliana Conceição Teodoro, Alvaro de Baptista-Neto, Maria Lucia Gonsales da Costa Araujo, Alberto Colli Badino

Microbiology Research Journal International, Page 1-8
DOI: 10.9734/mrji/2018/v26i630080

Streptomyces clavuligerus, initially described as a Cephamycin C producer, has been currently utilized to produce clavulanic acid (CA) which shows low antibiotic activity, being, however, a strong β-lactamase inhibitor, enzymes responsible for bacterial resistance to β–lactam antibiotics. Genetic improvement by physical and chemical agents is mandatory since, due to its genetic instability, industrial strains lose production capability making necessary a steady and frequent strain improvement and a screening procedure. The objective of this work was to obtain an increase in CA production in submerged cultures by utilizing mutants obtained by UV radiation of the wild strain Streptomyces clavuligerus ATCC 27064. Submerged cultures were performed, with the best mutants selected, in a 5L bench-scale bioreactor, batch-wise, utilizing a complex medium containing glycerol and a soybean protein isolate as the main components. The mutant 70 was able to produce a maximum CA concentration of 500 mg.L-1, approximately 1.6 times higher than the wild strain. Another finding was a higher CA productivity of 29.5 mg.h-1.L-1 with this mutant, although a lower specific growth rate had been observed.

Open Access Original Research Article

Glyphosate Degradation by Two Plant Growth Promoting Bacteria (PGPB) Isolated from Rhizosphere of Maize

E. Ezaka, A. K. Akintokun, P. O. Akintokun, L. B. Taiwo, A. C. O. Uthman, O. A. Oyedele, O. I. Aluko

Microbiology Research Journal International, Page 1-11
DOI: 10.9734/mrji/2018/v26i630081

This study was aimed at evaluating the possible utilization of glyphosate tolerant plant growth promoting bacteria (Pseudomonas aeruginosa and Bacillus cereus) for bioremediation of glyphosate polluted soil. The soil samples were spiked with 3.1 mg/ml, 7.2 mg/ml and 14.4 mg/ml of glyphosate and then inoculated with Pseudomonas aeruginosa and Bacillus cereus, level of glyphosate pollution before and after inoculation with the bacteria were determined using Gas Chromatography-Mass Spectroscopy (GC-MS) after extraction with acetonitrile. The bacteria showed significant ability to degrade glyphosate. Pseudomonas aeruginosa, Bacillus cereus, their mixed culture and control recorded percentage degradation of 76.11, 85.8, 75.8 and 49%, respectively at 3.1 mg/ml of glyphosate while At the concentration of 7.2 mg/ml, the percentage degradation by P. aeruginosa, Bacillus cereus, mixed culture of the isolates and control was 84.9, 72.7, 66.4% and 39.2%, respectively. The isolates also showed significant rate of degradation at the concentration of 14.4 mg/ml. The GC-MS results showed a significant variation in the degradation products obtained when compared with control. This study revealed that substantial amount of glyphosate was degraded by P. aeruginosa and Bacillus cereus. Hence, they may have great potential in bioremediation of glyphosate polluted soil.

Open Access Original Research Article

Local Stability of the Effects of Early Detection and Treatment on the Dynamics of Tuberculosis Using Lyapunov Function Method

James Andest, Joshua A. Kwanommu, Yakubu Isa Arisko

Microbiology Research Journal International, Page 1-10
DOI: 10.9734/mrji/2018/v26i630082

This study aims to use Lyapunov function method to build a SEIR model in the analysis of early detection and treatment. The SEIR model is a system of ordinary differential equations of six dimension developed from our compartment then building a mathematical theorem which guarantees the existence of a case of TB, the disease free-equilibrium and the total eradication of the disease from its host community that is disease endemic TB. Three theorems were proved using Lyapunov function method. With these, we concluded that in this research work have given a complete stability analysis of a tuberculosis model with two differential infectivity classes of early detected infected individual and late detected infected individual. By analysing this model, we found that it is locally asymptotically stable and possesses the only locally stable equilibrium state depending on the basic reproductive ratio R0 this steady state is either the endemic or the disease-free. The local stability of the infection-free equilibrium state implies that for an initial level of infection the disease will eventually fade out from the population when the condition for the stability, number R0 ≤1, hold. The condition R0>1, implies that the disease will persist in a population.

Open Access Original Research Article

Multidrug Resistant Salmonella Isolated from Street Foods in Chittagong, Bangladesh

Mohammad Mahmudul Hassan, Shajeda Begum, Abdullah Al Faruq, Mahabub Alam, Tareq Mahmud, Ariful Islam

Microbiology Research Journal International, Page 1-8
DOI: 10.9734/mrji/2018/v26i630083

Aim: The oodles raising of zoonotic multi-drug resistance (MDR) Salmonella spp. during the last decade, especially in developing countries by repeated challenges resulting from increased and indiscriminate use of antimicrobials in food animals, fish and crop production, and human treatments is one of the dismal issues and might have a dire consequence in near future. The nascent MDR Salmonella may also find their way to commonly available street foods in Bangladesh. Therefore, it is imperative to find out the existence of MDR Salmonella in street foods of Bangladesh.

Study Design:  We conducted a cross-sectional study to interrogate the prevalence of Salmonella spp. in street food items and the antimicrobial resistance pattern of isolated Salmonella spp.

Place and duration of Study: The study was conducted from January to June 2016 in 5 street side markets (Agrabad, Colnel Hat, Alonkar Bazar, Bohderhat Bazar and Riazuddin Bazar) of Chittagong City Corporation (CCC) area of Bangladesh.

Methodology: Standard microbiological methods were used for isolation and identification of Salmonella spp. from selected street foods. The antibiotic susceptibility tests were conducted by using disc diffusion method with commercially available 11 antimicrobials which are frequently used for medical and veterinary practices in Bangladesh.

Results: Prevalence of Salmonella spp. were varied from 60% to 78% among the street food items. The study revealed MDR Salmonella (resistance up to 6 of 11 tested antimicrobials) from each of the food items tested. Concerning the degree of resistance, among the isolated Salmonella, the highest resistances (100%) were detected for Ampicillin and Amoxicillin and lowest for Pefloxacin (around 13%). Moreover, the degree of resistance of Salmonella to antimicrobials also varied among the various street food items.  

Conclusion: The existence of MDR Salmonella notably a high rate in the street foods cues poor hygiene in street food production and it is a major threat for the advent of foodborne zoonoses.

Open Access Original Research Article

Antibiotic Susceptibility Profile of Bacteria Isolated from Fitness Machines in Selected Fitness Centers at Akure and Elizade University in Ondo State Nigeria

O. S. Fadare, O. B. Durojaye

Microbiology Research Journal International, Page 1-9
DOI: 10.9734/mrji/2018/v26i630084

Aim: This study seeks to determine the antibiotic susceptibility pattern of bacteria isolated from surfaces of fitness machines at fitness center located at Elizade University and Akure town.

Methods: Samples were collected from the different site of gym equipment including thread mill (handle, floor), bicep bench (handle), bike (handle, paddle), cruncher (handle, elbow) using sterile swab stick moistened with sterile buffered physiological solution. The swab sticks were immediately transferred to the laboratory for analysis. Standard microbiological techniques were used to identify the bacterial isolates. The antibiotic susceptibility profile of the isolates was determined by using standard antibiotics discs. 

Results: Out of the 31 isolates identified, Staphylococcus aureus 12(38.7%) was the predominant bacteria followed by Bacillus spp. 11(35.5%), Klebsiella spp. 4(12.9%), E. coli and Staphylococcus saprophyticus 2(6.45%) and Enterococcus spp. 1(3.23%). The susceptibility profile showed that all isolates were resistant to Amoxicillin (AM) and Augmentin (AU), Staphylococcus spp. isolated from different surfaces shows different susceptibility pattern to the used antibiotics, while Bacillus spp. Klebsiella spp. and E. coli also confer resistance to more than one commonly used antibiotic.

Conclusion: The results showed the occurrence of potential pathogenic bacteria in which their presence on the equipment surfaces could easily be transmitted between users and to the environment generally. The spread of these potential pathogenic microorganisms in the fitness centre can be prevented through frequent hand washing and use of hand sanitizer as well as daily cleaning of equipment surfaces before and after activities with disinfectants.