Methods for the Phenotypic Detection of Extended Spectrum Beta Lactamase (ESBL)-Producing Bacteria

1983. These enzymes possess the ability to inactivate susceptible β-lactam antibiotics i.e. penicillins, first, second and third generation cephalosporins and aztreonam, but not cephamycins and carbapenems . Their mode of action is by hydrolyzing the β-lactam ring. Even before the first β-lactam antibiotic (penicillin) was developed, resistance to β-lactam antibiotics was observed . ESBL genes are plasmids- and transposons- mediated, as such, can be spread easily to other species of bacteria. Resistance of ESBL- producing bacteria to the β-lactam antibiotics is a continuing cause of public health problems , it is increasingly being observed in community and nosocomial acquired infections. Detection and identification of these ESBLs in the laboratory is of prime importance for the selection of appropriate antibiotics to be used in the treatment of infections caused by ESBL- producing bacteria. The aim of this review is to explain in detail , several phenotypic methods used in the detection and confirmation of extended spectrum β lactamases. Keywords: Antibiotic resistance, ESBL, bacteria, phenotypic metho

Optimization of Crude Oil Biodegradation of Fungi Isolated from Refinery Effluent Site using Response Surface Methodology

The activities involved in the production and exploration of crude oil has constantly polluted the environment. This study investigated the ability of an indigenous fungus to utilize petroleum hydrocarbon. Response Surface Methodology was used to optimize the effects of pH, microbial concentration (spores/ml), and contact time (days) on the crude oil removal efficiency in refinery effluent. Monocillium sp. was isolated and used for the treatment of refinery effluent due to its predominance in the contaminated soil. Twenty experimental runs were analyzed to determine the effect of pH, microbial concentration and contact time on the oil removal efficiency. From theexperimental results obtained, a maximum oil removal efficiency of 98.42 % was achieved at a pH of 6.5, contact time of 14 days, and a microbial concentration of 3 spores/ml. The results obtained showed the percentage of crude oil removal in the effluent sample  increased with an increase in time. Optimization of the experimental result was achieved at a removal efficiency of 98.59 %, a contact time of 13.96 days, a pH of 6.85, and a microbial concentration of 3.01 spores/ml. The findings of this study revealed that Monocillium sp. is a viable hydrocarbon degrader, and can be used in the bioremediation of petroleum contaminated environments. Keywords: Response surface, optimization, bioremediation, hydrocarbon, removal efficiency, Monocillium sp

Comparative Assessment of Crude Oil Degradation by Monocillium sp. and Aspergillus niger

Fungi dwelling in soils contaminated by petroleum products can survive on these hydrocarbons due to the highly effective extracellular enzymes. Species belonging to the genus, Aspergillus are known to be efficient degraders of various classes of hydrocarbons as well as other organic contaminants. In this study, the biodegradation of crude oil by Aspergillus niger and Monocillium sp. were compared using laboratory microcosms.The moulds were isolated from a site receiving effluent from a petroleum refinery. They were identified using their macroscopic and microscopic characteristics and subsequently screened for their ability to utilize hydrocarbons for their metabolic requirements. Following the biodegradation studies, Aspergillus niger and Monocillium sp. recorded an increase in hydrocarbon utilizing fungal counts of 8.5 x 107 spores/ml and 6.1 x 107 spores/ml and crude oil weight loss of 80 % and 70 %. Both fungi were tested singly and in a consortium for their ability to degrade crude oil, itwas observed that Monocillium sp. and A.niger performed better when tested individually (94.2 %; 92.8 %) than in consortium (76.3 %). This may suggest that their combined metabolism may have created some antagonistic effect on the degradation process as opposed to their enzymatic capabilities which appeared to be more favourable to the process. The biodegradation experiment analysis showed that contact time plays a  significant role in biodegradation of crude oil (p<0.05), and Monocillium sp. and Aspergillus niger are excellent crude oil degraders and can be usedin the bioremediation of petroleum-contaminated soil and water. Keywords: Biodegradation, Aspergillus niger, Monocillium sp., soil, Crude oi

Utilization of petroleum hydrocarbons by indigenous fungi isolated from a petroleum refinery effluent site in Nigeria

No Abstract

Biodegradation Studies of Benzene, Toluene, Ethylbenzene and Xylene (BTEX) Compounds by Gliocladium sp. and Aspergillus terreus

Benzene, toluene, ethylbenzene and xylene (BTEX) are monoaromatic hydrocarbons found frequently in petroleum and its derivatives; and they are among the most important pollutants of soil and groundwater. This study focused on harnessing the enzymatic capabilities of filamentous fungi Gliocladium sp. and Aspergillus terreus, dwelling in a petroleum-contaminated soil to degrade benzene, toluene, ethylbenzene and xylene (BTEX) compounds. The biodegradation experiment was carried out using the fungi individually and in consortium in a batch culture containing mineral salts medium supplemented with 1% v/v BTEX. The experiments were carried out in triplicates at room temperature on a rotary shaker (180rpm) for twenty five days and aliquots were taken on a five day interval to determine the hydrocarbon utilizing fungal (HUF) count and residual BTEX in order to monitor the rate of biodegradation. The hydrocarbon utilizing fungal counts were determined by direct counting using a Neubauer  Haemocytometer while, the residual BTEX was determined using absorbance values measured using a spectrophotometer and the corresponding concentrations determined from a standard curve. The highest percentage degradation of BTEX was observed with Aspergillus terreus (89.1%) while, the least was observed with Gliocladium sp. (84.4%). The growth peak was attained on the 15th day in all treatments after which the HUF counts declined. Statistical analysis showed no significant difference (P>0.05) in the mean amounts of BTEX degraded and hydrocarbon-utilizing fungal counts between the treatments. The strains of Gliocladium sp. and Aspergillus terreus used in this study showed high ability for BTEX degradation thus, they are potential candidates for bioremediation of soils contaminated with monoaromatic hydrocarbons. Keywords: Biodegradation, BTEX, Gliocladium sp., Aspergillus terreus, Monoaromatic hydrocarbon

Effect of Feeding Linseed Oil and Vitamin A on Production Performance, Egg Characteristics and Egg Yolk Fatty Acids in Laying Hens under Sub-tropical Conditions

In the present study, linseed oil and vitamin A were fed to the laying hens during hot summer months to produce n-3 PUFA-enriched eggs. Two hundred and forty White Leghorn hens were randomly divided into 24 replicates and fed diets, for 12 weeks,2 with 0, 2, 3, or 4% linseed oil in combination with 3000 or 10000 IU vitamin A/kg. The results revealed that the supplementation of linseed oil and vitamin A to the diets did not affect (P>0.05) the production performance and egg characteristics in laying hens. However, body weight and feed intake were decreased (P0.05) for all dietary treatment groups. However, serum HDL-cholesterol was increased while LDL-cholesterol was decreased in laying hens with the increase in dietary linseed oil supplementation. The total n-6 PUFA and n-6/n-3 PUFA ratio were decreased while the n-3 PUFA were increased linearly (P0.05) the egg-yolk fatty acid contents. It might be concluded that, the supplementation of linseed oil to the laying hens kept at high environmental temperature is beneficial for the production of n-3 PUFA-enriched eggs without any considerable effects on production performance. © 2022, Animal Nutrition and Feed Technology. All Rights Reserved