Isolation of novel phenanthrene-degrading bacteria from seawater and the influence of its physical factors on the degradation of phenanthrene

ABSTRACT: This study aimed to isolate marine bacteria that can degrade phenanthrene and to investigate the effects of physical factors on the degradation of phenanthrene by the isolate. Two phenanthrene-degrading bacteria were isolated from seawater using an enrichment method. The isolated strains, designated PHPY and SK, degraded 99% of 500 mg/l phenanthrene in sterilized seawater within 15 and 10 days, respectively. In addition to phenanthrene, strain PHPY degraded anthracene, while strain SK could degrade fluorene. 16S rDNA-based phylogenetic analysis suggested that strains PHPY and SK might represent new genera of Sphingomonadaceae and Rhodobacteraceae, respectively. Studies on the effect of physical factors indicated that at temperatures of 30°C and 37°C, and pH 7.4-9.0, the strain PHPY could effectively grow and degrade phenanthrene. However, this strain could not grow at higher temperature or lower pH. Moreover, in the presence of NaCl at 22.79 g/l and even without added NaCl, strain PHPY was able to grow and degrade phenanthrene. PCR experiments with primers specific for large subunit of aromatic-ring-hydroxylating dioxygenase (bphA1f ) from Novosphingobium aromaticivorans F199 suggested that strain PHPY might possess genes for phenanthrene degradation that are not highly homologous to the genes in strain F199. Isolation of two new marine bacteria capable of degrading PAHs in this study confirmed that bacteria in genera Sphingomonadaceae and Rhodobacteraceae play an important role in the degradation of PAHs in marine environments

In Vitro Screening of Anti-lice Activity of Pongamia pinnata Leaves

Growing patterns of pediculocidal drug resistance towards head louse laid the foundation for research in exploring novel anti-lice agents from medicinal plants. In the present study, various extracts of Pongamia pinnata leaves were tested against the head louse Pediculus humanus capitis. A filter paper diffusion method was conducted for determining the potential pediculocidal and ovicidal activity of chloroform, petroleum ether, methanol, and water extracts of P. pinnata leaves. The findings revealed that petroleum ether extracts possess excellent anti-lice activity with values ranging between 50.3% and 100% where as chloroform and methanol extracts showed moderate pediculocidal effects. The chloroform and methanol extracts were also successful in inhibiting nymph emergence and the petroleum ether extract was the most effective with a complete inhibition of emergence. Water extract was devoid of both pediculocidal and ovicidal activities. All the results were well comparable with benzoyl benzoate (25% w/v). These results showed the prospect of using P. pinnata leave extracts against P. humanus capitis in difficult situations of emergence of resistance to synthetic anti-lice agents