Bioremediation has been proposed as a means of dealing with oil spills on the continent. However, the introduction of non-native organisms, including microbes, even for this purpose would appear to breach the terms of the Environmental Protocol to the Antarctic Treaty. This study therefore aimed to optimize the growth conditions and diesel degradation activity of the Antarctic native bacteria Arthrobacter spp. strains AQ5-05 and AQ5-06 through the application of a one-factor-at-a-time (OFAT) approach. Both strains were psychrotolerant, with the optimum temperature supporting diesel degradation being 10–15°C. Both strains were also screened for biosurfactant production and biofilm formation. Their diesel degradation potential was assessed using Bushnell–Haas medium supplemented with 0.5% (v/v) diesel as the sole carbon source and determined using both gravimetric and gas chromatography and mass spectrophotometry analysis. Strain AQ5-06 achieved 37.5% diesel degradation, while strain AQ5-05 achieved 34.5% diesel degradation. Both strains produced biosurfactants and showed high biofilm adherence. Strains AQ5-05 and AQ5-06 showed high cellular hydrophobicity rates of 73.0% and 81.5%, respectively, in hexadecane, with somewhat lower values of 60.5% and 70.5%, respectively, in tetrahexadecane. Optimized conditions identified via OFAT increased diesel degradation to 41.0% and 47.5% for strains AQ5-05 and AQ5-06, respectively. Both strains also demonstrated the ability to degrade diesel in the presence of heavy metal co-pollutants. This study therefore confirms the potential use of these cold-tolerant bacterial strains in the biodegradation of diesel-polluted Antarctic soils at low environmental temperatures.

Petroleum hydrocarbons, notably diesel oil, are the main energy source for running amenities in the Antarctic region and are the major cause of pollution in this area. Diesel oil spills are one of the major challenges facing management of the Antarctic environment. Bioremediation using bacteria can be an effective and eco-friendly approach for their remediation. However, since the introduction of non-native organisms, including microorganisms, into the Antarctic or between the distinct biogeographical regions within the continent is not permitted under the Antarctic Treaty, it is crucial to discover native oil-degrading, psychrotolerant microorganisms that can be used in diesel bioremediation. The primary aim of the current study is to optimize the conditions for growth and diesel degradation activity of an Antarctic local bacterium, Arthrobacter sp. strain AQ5-05, using the Plackett-Burman approach and response surface method (RSM) via a central composite design (CCD) approach. Based on this approach, temperature, pH, and salinity were calculated to be optimum at 16.30 °C, pH 7.67 and 1.12% (w/v), respectively. A second order polynomial regression model very accurately represented the experimental figures’ interpretation. These optimized environmental conditions increased diesel degradation from 34.5% (at 10 °C, pH 7.00 and 1.00% (w/v) salinity) to 56.4%. Further investigation of the kinetics of diesel reduction by strain AQ5-05 revealed that the Teissier model had the lowest RMSE and AICC values. The calculated values for the Teissier constants of maximal growth rate, half-saturation rate constant for the maximal growth, and half inhibition constants (μmax, Ks, and Ki), were 0.999 h−1, 1.971% (v/v) and 1.764% (v/v), respectively. The data obtained therefore confirmed the potential application of this cold-tolerant strain in the bioremediation of diesel-contaminated Antarctic soils at low temperature.

Modelado de la biodegradación en biorreactores de lodos de hidrocarburos totales del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)

Numerous papers fail to conduct statistical diagnostics of the nonlinear model that was used, and the data may be nonrandom, which is a need for all parametric statistical evaluation procedures that rely on random data. Whenever the diagnostic tests find that the residuals reflect a pattern, there are a range of treatments available, such as nonparametric analysis or transferring to a different model, which should resolve the issue. Organisms’ growth including viral infection cases over time usually exhibit a sigmoidal growth profile that exhibits lag time, acceleration to a maximal value and a final phase where the rate decreases and eventually reaches zero or an asymptote (A) is observed. For the analysis of the COVID-19 pandemic, the total infection case of SARS-CoV-2 in Brazil as of 15th of July 2020 to the 20th of December 2020 was modelled using several primary growth models with the Morgan-Mercer-Flodin (MMF) model found to be the best. We were the first to note on the high suitability of the MMF model to fit total death and infection cases for COVID-19. The least-squares technique used in normal nonlinear regression including in the MMF model must be subjected to the notion that the residual values must be random. In order to satisfy this requirement, we conduct the Wald–Wolfowitz runs test statistical diagnosis tests. The maximum number of runs counting was 5, and the predicted number of runs under the premise of randomness was 25.96. The z-value indicates how many normal errors the number of runs discovered exceeds the anticipated number of runs, and the p-value indicates how severe this z-value is. The significance is the same as with the other data on p-values. The null hypothesis that the residuals are really random can be rejected if the p-value is less than 0.05. Because the p-value was smaller than 0.05, the null hypothesis was dismissed, implying that there is strong evidence of non-randomness of the residues and further remedy is needed.

This present study aimed at examining the ability of cold-adapted Antarctic bacteria to tolerate and degrade diesel in the presence of different types of heavy metal co-pollutants. Arthrobacter sp. strains AQ5-05 and AQ5-06, originally isolated from Antarctic soils, were grown on Bushnell-Haas medium containing 1 ppm of heavy metal ions (As, Ag, Cd, Co, Cu, Cr, Hg, Ni, and Pb) supplemented with 3% (v/v) diesel. Diesel degradation was determined gravimetrically, while bacterial growth was evaluated by measuring the optical density of media (OD). 600 nm In the absence of heavy metal ions, strain AQ5-06 achieved 37.5% diesel mineralisation, while strain AQ5-05 achieved 34.5%. The diesel degrading abilities of both strains were significantly inhibited by exposure to < 1 ppm of Ag or Hg. In contrast, no change in degradation ability was observed using other tested heavy metals. The IC of Ag and Hg on 50 diesel degradation by the two strains were (0.2 and 0.4 ppm) and (0.3 and 0.2 ppm), respectively. Arthrobacter sp. Strains AQ5-05 and AQ5-06 may contain genes for alkane degradation and heavy metal resistance for remediating diesel-polluted soil in Antarctic and other cold regions. Antarctica, Arthrobacter sp., Biodegradation, Diesel, Heavy metals Effects of heavy metals on diesel metabolism of psychrotolerant strains of Arthrobacter sp. from Antarctica

This study was aimed at evaluating the phytochemical constituents and the antimicrobial activity of the seed oil of Moringa oleifera and garlic against some selected food-borne microorganisms (Staphylococcus aureus, Escherichia coli, Salmonella spp and Pseudomonas aeruginosa) using disc diffusion method. The results of the phytochemical screening revealed differences in the presence of the phytochemicals among the extracts. Saponins were detected in both Moringa oleifera and garlic seed oil, while alkaloid and tannins were observed in seed oil of garlic. Furthermore, the antibacterial assay results shows that the seed oil of Moringa oleifera was inactive against all the tested organisms, even at 100 % concentration. In contrast, garlic oil was found to be active against all the tested organisms. The highest inhibition was observed in E. coli (12 mm) at 100 % concentration, while at 20 % concentration, Salmonella Sp and P. aeruginosa showed resistance (00 mm). The antimicrobial activity of the seed oil of garlic may be attributed to its phytochemicals components which were not detected in the seed oil of Moringa oleifera. The results of this study have shown the potentials of the seed oil of garlic as an antimicrobial agent more especially in foods, by inhibiting the growth of the test organisms, which range from food-borne pathogens to food spoilage organisms.

Inadequate provision of potable drinking water in relation to teaming population is forcing most of the urban communities to drink untreated water obtained from traditional boreholes. Hence, the need to assess the portability of drinking water. In this research, boreholes water samples collected within Gombe city were investigated bacteriologically using multiple tube fermentation and pour plate methods to examine feacal coliform and coliform bacterial counts respectively; bacterial isolation was conducted using standard culture methods.  Identification of the bacterial Isolates were carried out by macroscopic, microscopic and biochemical examinations. Total coliform bacteria ranges from <3 to 11 MPN/100 ml and 1 to 3 MPN/100ml for faecal coliform. The borehole water samples from studied areas had high counts of faecal coliforms (Escherichia coli), and other pathogens like Entrobacter and Salmonella. The findings showed that all the borehole water analysed were not suitable for human consumption and may pose a serious threat to the health of consumers and therefore, there is need for treatment of these borehole waters by the borehole proprietors and also by simple treatment methods such as boiling, filtration before drinking and agitation by the consumers.    Keywords: Borehole water, Quality, Isolation, Identification, Coliform bacteria

Background: Disposable cups are usually used for drinking without any form of precleaning, this has the potential to expose individuals to pathogenic microorganisms, and unfortunately this issue has not been investigated in Gombe metropolis, hence, this study aimed to investigate the bacteriological aspect of the problem and to reduce the existing knowledge gap regarding this problem. Methods: Thirty samples were collected using simple random sampling from two different markets, then swab sticks pre-moistened with peptone water were used to swab the inner portions of the cups, put in sterile distilled water, serially diluted, inoculated on nutrient agar, and incubated. Identification of the isolates were done using their physical and biochemical characteristics, antibiotic susceptibility tests were done using disc diffusion method and interpreted using Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: The total mesophilic bacterial counts ranged from 3.0×10 5 to 9.9×10 5 CFU/ml. These isolates were identified and tested for their sensitivity to some antibiotics which revealed that Escherichia coli (E.coli ) were sensitive to augmentin, ampicillin, and ciprofloxacin, but intermediately resistant to chloramphenicol, Staphylococcus aureus (S. aureus) were sensitive to ciprofloxacin and augmentin, intermediately resistant to chloramphenicol, and resistant to ampicillin. Bacillus spp were sensitive to augmentin, ciprofloxacin, chloramphenicol and ampicillin, while Pseudomonas aeruginosa (P.aeruginosa) were sensitive to ciprofloxacin, augmentin, and chloramphenicol, but intermediately resistant to ampicillin. Conclusion: These new disposable ready-to-use cups harbored some potentially pathogenic bacteria which were resistant to some antibiotics. It is therefore recommended that pre-use hygiene practices should be done on these cups prior to use to avert the health effects of consuming these bacteria.