Open Access Original Research Article

Isolation, Screening and Identification of Biosurfactant-producing Bacteria from Hydrocarbon-polluted and Pristine Soils within Ogoniland, Nigeria

Ijeoma Vivian Nwaguma, Chioma Blaise Chikere, Gideon Chijioke Okpokwasili

Microbiology Research Journal International, Page 1-11
DOI: 10.9734/BMRJ/2016/26294

Aim: This study investigated the production of biosurfactant from bacteria isolated from hydrocarbon-polluted and pristine soils within Ogoniland in the Niger Delta region of Nigeria.

Methods: Baseline physicochemical parameters of the soil (total petroleum hydrocarbon (TPH), the nature of the soils, pH and temperature) were examined. The biosurfactant-producing bacteria were screened using emulsification assay, emulsification index (E24), lipase activity, haemolytic assay, oil spreading and tilted glass slide. The biosurfactant-producing bacteria were characterized by phenotypic, biochemical and molecular means.

Results: The respective baseline TPH, temperature and pH were 9,419 mg/kg, 28.5±0.4°C and 5.7±0.1 for hydrocarbon- polluted soil and 1.28 mg/kg, 27.5±0.3°C and 3.7±0.1 for pristine soil. Meanwhile, the respective soil types for the polluted and pristine were humus soil mixed with oil and ordinary humus. Six isolates (IVN-02, IVN-45, IVN-51, IVN-61, IVN-67 and IVN-74) out of forty one (41) distributed within the two different soil samples were found to produce biosurfactant. Phylogenetic analysis based on the 16S rRNA genes classified the six isolates as Pseudomonas sp. IVN02, Alcaligenes faecalis IVN45, Klebsiella pneumoniae IVN51, A. faecalis IVN61, Enterobacter sacchari IVN67 and P. aeruginosa IVN74 respectively. The isolates have been deposited at the GenBank under the accession numbers KT254065, KT254066, KT254060, KT254063, KT254061 and KT254059. 

Conclusion: This study demonstrated efficient biosurfactant production from bacterial isolate from hydrocarbon-polluted and pristine soils in Ogoniland within the Niger Delta region of Nigeria. The ability of the bacterial isolates from this region to produce biosurfactant is important considering the level of pollution in Ogoniland and the need to use indigenous and ecologically friendly products in the remediation process.

Open Access Original Research Article

Novel Bacillus Consortium for Degradation of 2,4- Dinitrotoluene: A Xenobiotic Compound

M. S. Smitha, Rajni Singh

Microbiology Research Journal International, Page 1-10
DOI: 10.9734/BMRJ/2016/25837

The xenobiotic compound 2,4-Dinitrotoluene (DNT) is used in the production of explosives (2,4,6-Trinitrotoluene,TNT), polyurethane/dyes, and in smokeless gunpowder. The cleanup of these compounds has gained much attention in the last decades due to hazardous nature of these compounds. Numerous bacterial strains capable of growing on DNT as the sole source of carbon, nitrogen and energy have been isolated by various scientists. Attempts to degrade DNT at high concentrations have never been found successful. The present study was conducted in Amity Institute of Microbial Biotechnology, Amity University between June 2010 and July 2011.

About 18 bacterial cultures were isolated from the contaminated sites in the presence of 0.001% (w/v) 2,4-DNT.Isolated strains were further screened on the basis of their tolerance towards 2,4-DNT by growing them in the presence of 0.001% to 0.03% (w/v) 2,4-DNT. Out of 18 strains, eight tolerated varying concentration of 2,4-DNT and were mixed in different permutation & combination for preparation of microbial consortia. The best consortium (No.4 with strains RSE165, RSA32, RSB80 and RSD127) was selected and subjected to molecular characterization. Bacterial strains used in this study were identified as Bacillus subtilis RSE165 (NCBI accession no. JQ887982), Bacillus megaterium RSA32 (KR051485), Bacillus cereus RSB80 (JQ040533) and Bacillus flexus RSD127 (KR051486).The analysis of the 2,4-DNT degradation capabilities of the best four individual strains and their consortium by GC analysis shows that the spectral peak of 2,4-DNT is completely replaced by three small peaks which indicate its utilization and degradation by the bacterial strains as well as by their consortium.

Open Access Original Research Article

Effect of Acid Adaptation of Listeria monocytogenes on Its Mild Thermal Inactivation in a Simulated Fruit Juice Supplemented with Carvacrol

Alex Tchuenchieu, Jean-Justin Essia Ngang, Martial Juengue, Sylvain Sado Kamdem, François- Xavier Etoa

Microbiology Research Journal International, Page 1-10
DOI: 10.9734/BMRJ/2016/27272

Aims: The use of mild heat treatment in combination with carvacrol has been reported as a possible way to quickly inactivate L. monocytogenes in fruit juices. This study aimed at assessing the possible effect of a prior adaptation of this pathogen to fruit juice acidity on its inactivation under the effect of such combined process.

Place and Duration of Study: Department of Microbiology of the University of Yaoundé I between November 2014 and April 2015.

Methodology: Citric acid-adapted and non-adapted cells were first produced. Their inactivation were then followed at 60°C, with and without carvacrol supplementation (30 µL/L),  in simulated fruit juices adjusted to pH 4.5 and Brix 12, pH being adjusted in one case with hydrochloric acid, in another with citric and lastly with malic acid. Inactivation curves were fitted to the Weibull inactivation model. 

Results: Acid adaptation of cells greatly increased their tolerance to the mild heat treatment. In fact, inactivation scales of acid-adapted cells were lower than those of non-adapted cells in all the tested conditions. The acidification of the model juice with citric or malic acid enhanced non-adapted cells inactivation. In contrast, with acid-adapted cells, only malic acid had a positive impact on inactivation with time.  In presence of citric acid, this inactivation was even lower than in model juice acidified with hydrochloric acid. A slight positive impact of carvacrol supplementation on non-adapted cells inactivation was noticed either comparing inactivation scale or inactivation with time in the tested conditions. This effect of carvacrol was minor with acid-adapted cells.

Conclusion: Microorganism acid adaptation phenomenon should be taken into consideration while studying the antimicrobial efficiency of low thermal process treatment of fruit juices.

Open Access Original Research Article

Effect of Woodchips on Bioremediation of Crude Oil-polluted Soil

Ugochukwu C. Okafor, Amechi S. Nwankwegu

Microbiology Research Journal International, Page 1-7
DOI: 10.9734/BMRJ/2016/27027

Aims: To evaluate the effectiveness of woodchips in bioremediation of crude oil contaminated soil, phytotoxicity assay as an index of soil biological activities (germination index) using a selected agricultural seed (Vicia faba) was also evaluated.

Methodology: Soil sample collection from Aguleri and Nkwelle Ezunaka, both in Anambra State. Samples were stored in polythene bags and transported to the laboratory. The soil samples were air dried, sieved through 2 mm mesh and stored in polythene bags at room temperature.

Results: Results showed that relatively alkaline pH was observed in woodchips amended option while slight acidity was reported in the control soil. Using woodchips as biostimulant achieved 75% crude oil contaminant removal but only 50% in the control. The microorganisms isolated from the present study included Klebsiella spp Pseudomonas spp Candida spp Fusarium, Penicillium spp.  Only 50% woodchips amended system produced growth of Vicia faba after 5 days incubation. There was no growth of Vicia fabaat 10% and 30% of woodchips at the same incubation time.

Conclusion: Result of the present study showed that hydrocarbon removal from the lithosphere can occur either naturally or by strategy enhancement with amendments but posited that rate and extent of removal in each case always differ. Present study also proved that for recovery of polluted media such as soil, information on the concentration of the additional limiting factors is scientifically crucial. 50% woodchips supported high crude oil remediation in the polluted soil. Woodchips therefore, is a potential source of nutrients for microbial activity and it habours microorganisms capable of utilizing hydrocarbons as source of carbon and energy thus, potentially useful in soil hydrocarbon spill response action.

Open Access Original Research Article

Potential Infections Linked to the Microbiological Quality of Swimming Pools _Kumasi, Ghana, West Africa

L. A. Adetunde, V. Ninkuu

Microbiology Research Journal International, Page 1-7
DOI: 10.9734/BMRJ/2016/24125

The risk of infections associated with microbiological quality of swimming pools in Kumasi was investigated. A variety of microorganisms can be found in swimming pools and similar recreational water environments which may be introduced in a number of ways. In many cases, the risk of illness or infection has been linked to faecal contamination of the water. Many of the outbreaks related to swimming pools would have been prevented or reduced if the pool had been well managed. Sixty (60) samples were collected from five hotels within three months, five samples in the afternoon and five samples in the morning. The samples were analyzed for the presence of Staphylococcus spp, Pseudomonas spp, Enterococcus spp, Salmonella spp, Shigella spp, total heterotrophic bacteria count, Vibrio cholerae, Escherichia coli, total coliform and faecal coliform using Plate Count Method and Multiple Tube Fermentation-Most Probable Number method respectively. Almost all the water samples were contaminated with Staphylococcus spp ranging from 7 x 101cfu/ml to 16 x 101 cfu/ml, Pseudomonas spp ranging from 4 x 101 cfu/ml to 19 x 101 cfu/ml, Enterococci spp ranging from 12 x 10cfu/ml to 14 x 101 cfu/ml, Total Heterotrophic bacteria count ranging from 6 x 101cfu/ml to 13 x 101 cfu/ml, Total and Faecal coliform ranging from 4 to 6 MPN/100 ml and 0-4 MPN/100 ml respectively. Salmonella spp, Shigella spp and Vibrio cholerae were not detected in all the water samples. E. coli was isolated in one swimming pool of the hotels while Enterococcus spp were isolated in two swimming pools. There were differences in bacteriological quality of the water samples obtained from the swimming pools.

Open Access Original Research Article

Preservation of Traditional Cheese Wagashi Using Essential Oils: Impact on Microbiological, Physico-chemical and Sensorial Characteristics

Philippe Sessou, Cyrille Boko, Gildas Hounmanou, Sawab Deen Osseni, Eustache Hounkpe, Paulin Azokpota, Issaka Youssao, Dominique Sohounhloue, Souaibou Farougou

Microbiology Research Journal International, Page 1-13
DOI: 10.9734/BMRJ/2016/27536

Aims: The high demand for food products without chemical additives has increased the use of natural preservatives like essential oils in food processing. The present study aimed to assess the impact of selected essential oils on the microbiological, physico-chemical and sensorial characteristics of preserved traditional cheese wagashi in order to improve its quality.

Materials and Methods: Microbiological and physico-chemical parameters were analysed repeatedly on days 0, 7, 30 and 60 using normalized methods in wagashi samples kept at 25°C and 4°C. Sensorial analyses were carried out once in 2 days old wagashi samples.

Results: Findings show that none of the analysed samples during the experimental period contains pathogenic microorganisms including Salmonella spp, Staphylococcus aureus, Escherichia coli and the spores of Clostridium spp. The pH of wagashi samples kept at 25°C decreased over time while their acidity, as well as the thiobarbituric acid index increased. The trend of these physico-chemical parameters was similar at 25°C as at 4°C; however the fluctuations were quite lower for the pH and the acidity at 4°C than at 25°C. For the sensorial quality of the initial products, the sample treated with the essential oil of Cymbopogon citratus was well appreciated by the tasters who mentioned that it was of good quality followed by the sample of wagashi treated with the essential oil of Pimenta racemosa qualified of fairly good. Samples treated with the essential oils of  Ocimum gratissimum and Syzygium aromaticum were of acceptable quality.

Conclusion: This study revealed that the application of essential oils of Cymbopogon citratus and Pimenta racemosa in replacement of chemical additives constitutes a reliable alternative for the preservation of wagashi. However, a thorough study on the biochemical characterization of the samples is necessary to appreciate the quality of the elaborated products.