Optimisation of biodegradation conditions for waste canola oil by cold-adapted Rhodococcus sp. AQ5-07 from Antarctica

Background: The potential waste canola oil-degrading ability of the cold-adapted Antarctic bacterial strain Rhodococcus sp. AQ5-07 was evaluated. Globally, increasing waste from food industries generates serious anthropogenic environmental risks that can threaten terrestrial and aquatic organisms and communities. The removal of oils such as canola oil from the environment and wastewater using biological approaches is desirable as the thermal process of oil degradation is expensive and ineffective. Results: Rhodococcus sp. AQ5-07 was found to have high canola oil-degrading ability. Physico-cultural conditions influencing its activity were studied using one-factor-at-a-time (OFAT) and statistical optimisation approaches. Considerable degradation (78.60%) of 3% oil was achieved by this bacterium when incubated with 1.0 g/L ammonium sulphate, 0.3 g/L yeast extract, pH 7.5 and 10% inoculum at 10°C over a 72-h incubation period. Optimisation of the medium conditions using response surface methodology (RSM) resulted in a 9.01% increase in oil degradation (87.61%) when supplemented with 3.5% canola oil, 1.05 g/L ammonium sulphate, 0.28g/L yeast extract, pH 7.5 and 10% inoculum at 12.5°C over the same incubation period. The bacterium was able to tolerate an oil concentration of up to 4.0%, after which decreased bacterial growth and oil degradation were observed. Conclusions: These features make this strain worthy of examination for practical bioremediation of lipid-rich contaminated sites. This is the first report of any waste catering oil degradation by bacteria originating from Antarctica

Evaluation of the Effifacy of a Phage Cocktail against gentamicin-resistance Klebsiella pneumoniae

The bacteria Klebsiella pneumoniae is one of top aetiological agents associated with nosocomial infection, and it has gained its notoriety with the emergence of multidrug resistance strains. In this study, we evaluated the effect of lytic bacteriophage cocktail isolated from our local sewage as potential antimicrobial candidate against Gentamicinresistant Klebsiella pneumoniae. A total of five clinical-acquired K. pneumoniae isolates including a carbapenem-resistant K. pneumoniae (CRKP) strain showed resistance towards gentamicin (GN). Phages were isolated using double-layer agar method against clinical- and community-acquired K. pneumoniae as host strains. Phage characterization using PCR partial sequencing of different viral genes; Lysin, Major Capsid Protein (g23) and Tail Fiber Protein has suggested that these phages possibly belonged to Myoviridae (ɸKPaV04, ɸKPaV08, ɸKPaV12) and Podoviridae (ɸKPaV03, ɸKPaV10). The characterized phages was selected for cocktail have exhibited high titer and broad host range with 22-44% lysis towards a panel of 18 K. pneumoniae strains. The antimicrobial efficacy of a single phage cocktail administration showed 80% growth suppression of GN-resistant K. pneumoniae after 18 h of incubation. Suggesting the possibility of phage cocktail to be used against nosocomial infections by multidrug resistant bacteria including being an alternative to antibiotic GN in the treatment of CRKP infections

Biosurfactant production and growth kinetics studies of the waste canola oil-degrading bacterium Rhodococcus erythropolis AQ5-07 from Antarctica

With the progressive increase in human activities in the Antarctic region, the possibility of domestic oil spillage also increases. Developing means for the removal of oils, such as canola oil, from the environment and waste “grey” water using biological approaches is therefore desirable, since the thermal process of oil degradation is expensive and ineffective. Thus, in this study an indigenous cold-adapted Antarctic soil bacterium, Rhodococcus erythropolis strain AQ5-07, was screened for biosurfactant production ability using the multiple approaches of blood haemolysis, surface tension, emulsification index, oil spreading, drop collapse and “MATH” assay for cellular hydrophobicity. The growth kinetics of the bacterium containing different canola oil concentration was studied. The strain showed β-haemolysis on blood agar with a high emulsification index and low surface tension value of 91.5% and 25.14 mN/m, respectively. Of the models tested, the Haldane model provided the best description of the growth kinetics, although several models were similar in performance. Parameters obtained from the modelling were the maximum specific growth rate (qmax), concentration of substrate at the half maximum specific growth rate, Ks% (v/v) and the inhibition constant Ki% (v/v), with values of 0.142 h−1, 7.743% (v/v) and 0.399% (v/v), respectively. These biological coefficients are useful in predicting growth conditions for batch studies, and also relevant to “in field” bioremediation strategies where the concentration of oil might need to be diluted to non-toxic levels prior to remediation. Biosurfactants can also have application in enhanced oil recovery (EOR) under different environmental conditions