Burkholderia sp. USM (JCM15050) isolated from oil-polluted wastewater is capable of utilizing palm oil products and glycerol to synthesize poly(3-hydroxybutyrate) [P(3HB)]. To confer the ability to produce polymer containing 3-hydroxyhexanoate (3HHx), plasmid (pBBREE32d13) harbouring the polyhydroxyalkanoate (PHA) synthase gene of Aeromonas caviae (phaC(Ac)) was transformed into this strain.
We attempted to synthesize a polyhydroxyalkanoate (PHA) containing newly reported 3-hydroxy-4-methylvalerate (3H4MV) monomer by using wild type Burkholderia sp. USM (JCM15050) and its transformed strain harboring the PHA synthase gene of Aeromonas caviae (phaCAc). The introduction of 3H4MV as a second monomer will improve the material properties of 3HB-based polymers. To promote the accumulation of PHA containing 3H4MV monomer, isocaproic acid was provided as co-carbon source. Approximately 1mol% of 3H4MV was detected in wild type Burkholderia sp. cultures when they were fed glucose or fructose together with isocaproic acid. Thus, the wild type strain can synthesize the 3H4MV monomer. High 3H4MV fractions, of about 40mol%, were obtained when the transformed strain was cultivated on glucose or fructose together with isocaproic acid. In addition, the ability of the transformed strain to mobilize accumulated PHA containing 3H4MV monomer was demonstrated in this study. This is the first report on mobilization of the 3H4MV monomer.
Antibiotic resistance is a major health concern globally and has been estimated to cause 10 million deaths worldwide by year 2050 if the current trend of inappropriate and excessive use of antibiotics continues. Although, the discovery of antibiotics has saved countless of lives for the past 80 years, increasing levels of bacterial resistance to antibiotics would jeopardize the progress in clinical and agricultural sectors and may cause life-threatening situations even for previously treatable bacterial infections. Antibiotic resistance would increase the levels of poverty of low-middle income countries mostly due to extended hospital stays, higher cost of treatment and untimely deaths that directly affect the total productivity rate. Recent incidences of antibiotic resistance have been gradually increasing globally and this may potentiate horizontal transmission of the resistant gene and have been linked with cross-resistance to other antibiotic families as well. This review summarizes the global burden of antibiotic resistance from the economic viewpoint, highlights the recent incidences of antibiotic resistance mainly related to Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, Salmonella spp. and Staphylococcus aureus, describes the common mechanistic actions of antibiotic resistance and potential strategies to overcome antibiotic resistance.