Improving the short-chain fatty acids production of waste activated sludge stimulated by a bi-frequency ultrasonic pretreatment

Short-chain fatty acids (SCFAs) are the most important intermediate in the waste activated sludge (WAS) fermentation process. This work explored a novel approach to improve the SCFAs production from WAS. Experimental results showed that the disintegration and acidification of WAS were enhanced markedly by using bi-frequency (28+40 kHz) ultrasonic pretreatment compared with monofrequency (28 kHz and 40 kHz) ultrasonic pretreatments. After 28 + 40 kHz ultrasonic pretreatment, the SCOD concentration increased from original 363 mg COD l(-1) to 10810 mg COD l(-1) which was 1.53-fold and 1.44-fold of the values obtained with 28kHz and 40kHz ultrasonic pretreatments, respectively. The maximum SCFAs production reached 7587 mg COD l(-1) in the 28 + 40 kHz test which was respectively 1.25-fold and 1.31-fold of that in the 28 kHz (6053 mg COD l(-1)) and 40 kHz (5809 mg COD I(-1)) tests. This was the highest SCFAs production obtained so far using WAS, pretreated by ultrasonic technology, as the renewable carbon source. SCFAs composition analysis revealed there was more acetic acid (3992 mg COD l(-1), accounted for 52.6% of the total SCFAs) for the 28+40 kHz ultrasonic pretreatment which was beneficial to many subsequent bioprocesses.

Engineering a single ubiquitin ligase for the selective degradation of all activated ErbB receptor tyrosine kinases

Interrogating specific cellular activities often entails the dissection of posttranslational modifications or functional redundancy conferred by protein families, which demands more sophisticated research tools than simply eliminating a specific gene product by gene targeting or RNA interference. We have developed a novel methodology that involves engineering a single SCF(βTrCP)-based ubiquitin ligase that is capable of not only simultaneously targeting the entire family of ErbB receptor tyrosine kinases for ubiquitination and degradation, but also selectively recruiting only activated ErbBs. The engineered SCF(βTrCP) ubiquitin ligase effectively blocked ErbB signaling and attenuated oncogenicity in breast cancer cells, yet had little effect on the survival and growth of non-cancerous breast epithelial cells. Therefore, engineering ubiquitin ligases offers a simple research tool to dissect the specific traits of tumorigenic protein families, and provides a rapid and feasible means to expand the dimensionality of drug discovery by assessing protein families or posttranslational modifications as potential drug targets.

Distribution of phylogenetic groups, sequence type ST131, and virulence-associated traits among Escherichia coli isolates from men with pyelonephritis or cystitis and healthy controls

Urinary tract infections (UTI), which are mostly caused by Escherichia coli, are an important public health problem worldwide. Although men experience diverse UTI syndromes, there have been relatively few molecular-epidemiological studies of UTI pathogenesis in men. We studied the distribution of 22 E. coli virulence factor (VF) genes, major phylogenetic groups, sequence type ST131, and UTI-associated O antigens among 101 pyelonephritis, 153 cystitis and 135 fecal healthy control E. coli isolates from men aged 30-70 years in a regional area of NSW, Australia. Overall, the studied traits exhibited a prevalence gradient across these groups, highest in pyelonephritis, intermediate in cystitis, and lowest among fecal isolates. Differences in virulence gene prevalence between cystitis and pyelonephritis isolates were limited to eight genes. The UTI-associated O antigens were also distributed widely, but types O6, O25 and O75 were significantly associated with pyelonephritis. The ST131 clonal group, which accounted for 13% of isolates overall (22% of group B2 isolates), likewise exhibited a significant descending prevalence gradient from pyelonephritis (36%), through cystitis (8%), to fecal (0%) isolates. These findings contribute to better understanding of the pathogenesis of UTIs in men and identify specific VF genes and O types, and a prominent clonal group (ST131), as being important in UTI pathogenesis in this population.

Role of glutathione in detoxification of copper and cadmium by yeast cells having different abilities to express cup1 protein

ABSTRACT Although copper is an essential metal and cadmium is an environmental pollutant, both are toxic when present in excess. Metallothionein and glutathione are two of the key components that participate in detoxification of copper and cadmium. In the present study the role of glutathione in resistance to copper and cadmium was investigated with the yeast Saccharomyces cerevisiae. The yeast cells used in this study have different abilities to produce glutathione and Cup1 protein, the yeast metallothionein homolog encoded by CUP1 gene. It was demonstrated that Cup1 protein plays a dominant role in buffering excess copper, and yeast does not depend on glutathione to reduce copper toxicity whether it possesses single or multiple copies of CUP1. In fact, excess copper can cause glutathione oxidation and depletion and damage the glutathione system. On the other hand, it was indicated that Cup1 protein is an important cadmium-detoxifying component, and the glutathione system can positively respond to cadmium. In yeast containing single or multiple copies of CUP1, glutathione is an indispensable line of defense against cadmium. Yeast having glutathione and no Cup1 protein is not able to grow in medium containing excess copper, but can tolerate higher concentrations of cadmium. In addition, it was found that yeast, independent of glutathione, can efficiently remove excess copper, whereas it cannot promptly eliminate accumulated cadmium regardless of having glutathione or not.

Enhanced degradation of azo dye alizarin yellow R in a combined process of iron-carbon microelectrolysis and aerobic bio-contact oxidation

PURPOSE

With the aim of enhanced degradation of azo dye alizarin yellow R (AY) and further removal of the low-strength recalcitrant matter (LsRM) of the secondary effluent as much as possible, our research focused on the combination of aerobic bio-contact oxidation (ABO) with iron/carbon microelectrolysis (ICME) process.

MATERIALS AND METHODS

The combined ABO (with effective volume of 2.4 l) and ICME (with effectively volume of 0.4 l) process were studied with relatively short hydraulic retention time (HRT) of 4 or 6 h.

RESULTS

At the HRT of 6 h with the reflux ratio of 1 and 2, the AY degradation efficiency in the final effluent was >96.5%, and the total organic carbon (TOC) removal efficiency were 69.86% and 79.44%, respectively. At the HRT of 4 h and the reflux ratio of 2, TOC removal efficiency and AY degradation efficiency were 73.94% and 94.89%, respectively. The ICME process obviously enhanced the total AY removal and the generated micromolecule acids and aldehydes then that wastewater backflow to the ABO where they were further biodegraded.

CONCLUSION

The present research might provide the potential options for the advanced treatment azo dyes wastewater with short HRT and acceptable running costs.

Natural outbreak of Streptococcus agalactiae (GBS) infection in wild giant Queensland grouper, Epinephelus lanceolatus (Bloch), and other wild fish in northern Queensland, Australia

Ninety-three giant Queensland grouper, Epinephelus lanceolatus (Bloch), were found dead in Queensland, Australia, from 2007 to 2011. Most dead fish occurred in northern Queensland, with a peak of mortalities in Cairns in June 2008. In 2009, sick wild fish including giant sea catfish, Arius thalassinus (Rüppell), and javelin grunter, Pomadasys kaakan (Cuvier), also occurred in Cairns. In 2009 and 2010, two disease epizootics involving wild stingrays occurred at Sea World marine aquarium. Necropsy, histopathology, bacteriology and PCR determined that the cause of deaths of 12 giant Queensland grouper, three wild fish, six estuary rays, Dasyatis fluviorum (Ogilby), one mangrove whipray, Himantura granulata (Macleay), and one eastern shovelnose ray, Aptychotrema rostrata (Shaw), was Streptococcus agalactiae septicaemia. Biochemical testing of 34 S. agalactiae isolates from giant Queensland grouper, wild fish and stingrays showed all had identical biochemical profiles. The 16S rRNA gene sequences of isolates confirmed all isolates were S. agalactiae; genotyping of selected S. agalactiae isolates showed the isolates from giant Queensland grouper were serotype Ib, whereas isolates from wild fish and stingrays closely resembled serotype II. This is the first report of S. agalactiae from wild giant Queensland grouper and other wild tropical fish and stingray species in Queensland, Australia.

Detection of Laribacter hongkongensis using species-specific duplex PCR assays targeting the 16S rRNA gene and the 16S-23S rRNA intergenic spacer region (ISR)

AIMS

For the rapid detection of Laribacter hongkongensis, which is associated with human community-acquired gastroenteritis and traveller's diarrhoea, we developed a duplex species-specific PCR assay.

METHODS AND RESULTS

Full-length of the 16S-23S rRNA intergenic spacer region (ISR) sequences of 52 L. hongkongensis isolates were obtained by PCR-based sequencing. Two species-specific primer pairs targeting 16S rRNA gene and ISR were designed for duplex PCR detection of L. hongkongensis. The L. hongkongensis species-specific duplex PCR assay showed 100% specificity, and the minimum detectable level was 2.1 × 10(-2) ng μl(-1) genomic DNA which corresponds to 5000 CFU ml(-1).

CONCLUSIONS

The high specificity and sensitivity of the assay make it suitable for rapid detection of L. hongkongensis.

SIGNIFICANCE AND IMPACT OF THE STUDY

This species-specific duplex PCR method provides a rapid, simple, and reliable alternative to conventional methods to identify L. hongkongensis and may have applications in both clinical and environmental microbiology.

Prevalence and genetic diversity of pneumococcal serogroup 6 in Australia

The prevalence of the newly discovered pneumococcal serotype 6C has increased in some countries since the introduction of seven-valent conjugate pneumococcal vaccine (PCV7). The distribution of invasive serogroup 6 serotypes, in Australia, including 6C and 6D, has not been reported previously. During the period 1999 to 2008, 6097 isolates were referred to the New South Wales Pneumococcal Reference Laboratory for serotyping. Of these, 847 were identified by Quellung reaction as belonging to serogroup 6 and 702 were available for further study. Serotypes were determined by serotype-specific PCR as follows: 6A, 197 (28.1%); 6B, 452 (64.4%); 6C, 52 (7.4%) and one 6D. The average numbers of invasive serogroup 6 isolates, per annum, fell from 62.2 before (2000-2005) to 49.7 after (2006-2008) the introduction of PCV7. The proportions of invasive 6B fell (from 72.4% to 47.3%, p 0.03), those of 6C rose (from 3.3% to 17%, p 0.02) significantly and those of 6A remained fairly constant (24.3% vs 27%, p 0.69) between the two periods. All 6C and 6D and selected 6A and 6B isolates were further characterized by multilocus sequence typing and sequence analysis of cps genes cpsA-cpsB (wzg-wzh) and wchA-wciN(beta) -wciO, wciP. Results showed considerable diversity within serotype 6C, apparently as a result of both mutation and recombination. Sequence typing indicates that, in Australia, 6C has been largely derived from 6A. The genetic diversity and rapid increase in incidence of serotype 6C causing invasive pneumococcal disease has potential implications for vaccine efficacy.