Open Access Original Research Article

The Inhibitory Effect of the Combination Treatment of Rifampicin and D-limonene on the Growth and Biofilm Formation of Staphylococcus epidermidis RP62A

Anna K. Yeung-Cheung, Wardah Alakrah, Eymi N. Orellana, Olivia C. Drew, Cristina M. Commisso

Microbiology Research Journal International, Page 1-13
DOI: 10.9734/mrji/2021/v31i1030346

Aims: To discover an alternative chemical that could potentially be used in combination with antibiotics to inhibit the growth of Staphylococcus epidermidis RP62A.

Study Design: The studies of the growth inhibition in both the biofilm forming strain of S. epidermidis RP62A and the wild-type strain ATCC 12228, were conducted with different concentrations of rifampicin and D-limonene using the measurement of the optical density.

Place and Duration of Study: All experiments were conducted in the Department of Biology at Manhattanville College between September 2015 and December 2019.

Methodology: Different concentrations of rifampicin (0.0025 µg/mL, 0.005 µg/mL, 0.01 µg/mL and 0.02 µg/mL) and D-limonene (152.8 µg/mL, 305.6 µg/mL, 611.2 µg/mL and 1222.4 µg/mL) were used in the study. The minimal inhibitory concentrations (MIC) of rifampicin and D-limonene on RP62A and ATCC 12228 were obtained. The combination of rifampicin and D-limonene on the inhibition of the growth of RP62A and ATCC 12228 was conducted using a microtiter plate by measuring optical density. The alamarBlue® assay was further used to evaluate the viability of RP62A and ATCC 12228 with the combination treatment. The biofilm assay was then conducted on RP62A with the combination treatment of rifampicin and D-limonene.

Results: The MIC of the combination treatment of rifampicin and D-limonene on RP62A was found to be 0.01 µg/mL and 1222.4 µg/mL respectively. A combination treatment of 0.005 µg/mL of rifampicin with 611.2 µg/mL of D-limonene significantly inhibited the growth and biofilm formation of RP62A than the same concentration of rifampicin.

Conclusion: The addition of the D-limonene to the rifampicin was found to be effective in inhibiting the growth and biofilm formation of RP62A. This indicates that the combination of alternative mineral oil may have the potential to lower the antibiotic concentration in the inhibition of the growth of the bacteria S. epidermidis.

Open Access Original Research Article

Prevalence and Antimicrobial Susceptibility Profiles of Salmonella Species in Poultry Farm Environments in Ghana

Rahman Abilla, Adetunde Lawrence Adelani, Kennedy Gyau Boahen, Linda Aurelia Ofori

Microbiology Research Journal International, Page 14-23
DOI: 10.9734/mrji/2021/v31i1030347

Background: Poultry is one of most consumed meat products in Ghana. Outbreaks of Salmonella spp infections due to consumption of contaminated undercooked poultry products are of high risk to human health. This study determined the prevalence and antimicrobial resistance patterns of Salmonella spp in the poultry environment in the Kwabre East municipality.

Method: A total of 114 samples consisting of 38 faecal, 38 dust and 38 feed were taken from a total of 38 farms that consented to the study. Sterile nurse’s caps were worn over the boot to collect faecal and worn over the palm to collect dust samples whilst a sterile spatula was used to collect feed samples. Salmonella was isolated using standard culture and biochemical methods. The antimicrobial susceptibility and the minimum inhibitory concentration (MIC) profile was determined using the disk diffusion method under the guidelines and interpretations published by (CLSI, 2018).

Results: In all, five (5/38; 13.2 %) of the farms were positive for Salmonella with a sample level prevalence of 5.3 % (n=6). Layers were predominantly reared (92.1 %) and all the samples positive for Salmonella (n=6; 17.1 %) were from the layers. Salmonella strains were prevalent in the dust (n=3; 50 %) followed by faecal matter and then feed. Antimicrobial agents were widely used by farmers for treatment purposes. Salmonella strains were resistant to tetracycline (100 %), trimethoprim-sulphamethoxazole (66.7 %), ampicillin (50 %), chloramphenicol (50 %) and ciprofloxacin (16.7 %). Multi-drug resistance (MDR) was observed among four (n=4; 66.7 %) Salmonella strains.

Conclusion: The presence of Salmonella in poultry environment and the emergence of multiple drug resistant is a major risk for poultry product contamination. Finding from this study will guide decontamination policies in targeting Salmonella in the poultry industry. It will be needful to also investigate the molecular mechanism of antimicrobial resistance and characterize the strains using molecular methods.

Open Access Original Research Article

Utilization of Various Starch Hydrolysates and Defatted Proteins by Bacillus cereus for Microbial Synthesis of Methionine in Submerged Medium

C. C. Ezemba, I. A. Ekwealor

Microbiology Research Journal International, Page 24-35
DOI: 10.9734/mrji/2021/v31i1030348

Three of the methionine-producing bacteria previously isolated from different soil ecovars in Owerri, characterized as Bacillus cereus no: DS13, RS16 and AS9, based on 16s rRNA sequencing, were screened for utilization agricultural products for production of methionine. Experimental studies on the Bacillus strains were carried out to examine the use of various starch hydrolysates from different agricultural products: wheat, sorghum, cassava, cocoyam, yam, plantain, millet, corn, potato, rice and defatted plant proteins: pigeon pea, cowpea, bambaranut, groundnut and soybean meal as source of carbon and nitrogen, respectively for the production of methionine. The result of the influence of various carbon and nitrogen sources on methionine production showed that 2.32mg/ml methionine accumulation in the culture broth of B. cereus DS13 when corn-starch hydrolysate/defatted groundnut meal was used, while B. cereus RS16 and Bacillus cereus DS13 gave the same methionine yield of 2.22mg/ml with corn-starch hydrolysate/defatted groundnut meal and sorghum hydrolysate/soyabean meal respectively. Bacillus cereus AS9 utilized wheat starch hydrolysate/soaybean meal, followed by plaintain-starch hydrolysate/bambaranut to produced 1.79mg/ml and 1.78mg/ml methionine respectively. Methionine was accumulated in the fermentation broth of the Bacillus strains after a fermentation period of 96h. This study indicates the possible utilization of agricultural products as substrates for L-methionine production in submerged medium especially when considering the limitations of producing methionine by fermentation processes.

Open Access Original Research Article

Effect of Pristine Soil Addition and Cow Dung Treatment on the Community Structure Post Bioremediation

Barisiale S. Baranu, Chimezie J. Ogugbue, Gideon C. Okpokwasili

Microbiology Research Journal International, Page 36-44
DOI: 10.9734/mrji/2021/v31i1030349

The pollution of crude oil on agricultural soil has become a menace in the world today. The ecologically friendly approach of restoring this polluted soil back to its original state is pertinent. In this study, 1000 g of crude oil polluted soil was amended with 12.5g of cow dung and 500 g of unpolluted soil, 1000 g of polluted soil with crude oil without cow dung amendment, and 1000 g of unpolluted soil without crude oil and cow dung amendment was the control. The setup was monitored for their physicochemical parameters such as total petroleum hydrocarbon (TPH), polyaromatic hydrocarbon (PAH), temperature, pH, electrical conductivity (Ec), and total nitrogen. The microbiological characterization for viable and culturable was done for total heterotrophic bacteria (THB) and hydrocarbon utilizing bacteria (HUB) while non-culturable but viable characterization was done using metagenomics-shotgun analysis to compare the changes in community structure before, during, and after remediation. The THB observed in the samples were 1.9 x 107, 1.3 x 103, 4.0 x 106, 3.58 x 108, 2.15 x 109 while HUB was 1.6 x 103, 1.0 x 101, 1.67 x 103, 2.5 x 104, and 3.55 x 104 respectively for A (unpolluted soil), B (polluted soil without 1.67 x 103, 2.5 x 104, and 3.55 x 104 respectively for A (unpolluted soil), B (polluted soil without treatment), J1 (month 1), J2 (month 2), and J3(month 3). Over 90 % removal of the TPH was achieved by the treatment. The molecular characterization showed that Proteobacteria was the dominant phylum identified in the pristine soil, but Actinobacteria were the most dominant in the soil  with  treatment.  Nitrogen-fixing  Bradirhizobium  elkanii  was found to be 0.66%, 5.11%, 10.43% before pollution, during natural attenuation, and with unpolluted soil addition with cow dung amendment. Denitrifying Nocardiodes daejeonensis and Nocardiodes terra were identified at 0.1 and 2.0% respectively only three (3) months after the end of the bioremediation treatment.

Open Access Original Research Article

Substitution of Pro165 in Transmembrane 4 of PfCRT Abolishes Lysosome Acidification Function in Stably Transfected HEK-293F Cells

Fadi Baakdah, Elias Georges

Microbiology Research Journal International, Page 45-55
DOI: 10.9734/mrji/2021/v31i1030352

The Plasmodium falciparum chloroquine resistance transporter (PfCRT) is localised on the parasite digestive vacuole, an organelle that maintains an acidic lumen. Here we demonstrated the isolation of HEK-293F cells stably expressing wild type 3D7 and mutant Pfcrt alleles. Immuno-fluorescence staining of HEK-293F transfectants confirms the localization of Pfcrt alleles to the lysosomal vesicles. Moreover, cells expressing mut-PfCRTETSE showed greater lysosomal acidification as demonstrated by the dramatic increase in the accumulation of two weak bases, acridine orange and CytiPainter LysoOrange dyes. Furthermore, HEK-293 cells stably expressing mut-PfCRTETSE with a single substitution of proline 165 in transmembrane 4 completely inhibited the accumulation of weak bases. Taken together, our results demonstrate the role of Pro165 in PfCRT lysosomal acidification function in HEK-293F cells.