Safety assessment of Rhodobacter azotoformans SY5 for potential application in Chinese mitten crab Eriocheir sinensis.

Rhodobacter species are promising beneficial microbes that can improve growth performance, immunity and antioxidant capability in aquatic crustaceans. Yet the safety of Rhodobacter azotoformans for potential application in Chinese mitten crab Eriocheir sinensis is still unclear. In the present study, R. azotoformans SY5, a potential probiotic additive that can significantly improve the growth performance, immunity, antioxidant capability, and disease resistance in E. sinensis, was evaluated for safety through whole genome sequencing, antibiotic resistance, toxic metabolites, virulence, and crab tolerance assays. The results indicated that R. azotoformans SY5 only harboured the acyl carrier protein-encoding gene (acpP) that was universal in probiotic bacteria with the function of bacterial fatty acid biosynthesis, exhibited high susceptibility to aminoglycosides, penicillins, polymyxins, polyphosphates, quinolones, and tetracyclines antimicrobials, and possessed inability to produce hemolysin, hydrogen sulphide, nitrite, ammonia, and phenylpyruvate. In addition, R. azotoformans SY5 showed no pathogenicity for E. sinensis with the seven-day acute intraperitoneal LD50 value of above 6.0 × 109 cfu/ml and 30-day chronic oral LD50 of above 6.0 × 109 cfu/g diet. To our knowledge, this is the first report on the safety of R. azotoformans for potential application in Chinese mitten crabs.

Global cooling and enhanced Eocene Asian mid-latitude interior aridity.

Tibetan Plateau uplift has been suggested as the main driving force for mid-latitude Asian inland aridity (AIA) and for deposition of thick aeolian sequences in northern China since the Miocene. However, the relationship between earlier AIA and Tibetan Plateau mountain building is uncertain because of a lack of corresponding thick aeolian sequences with accurate age constraints. We here present results for a continuous aeolian sequence that spans the interval from >51 to 39 Ma from the eastern Xorkol Basin, Altun Shan, northeastern Tibetan Plateau. The basal age of the studied sequence postdates initial uplift of the Tibetan Plateau by several million years. Our results indicate that the local palaeoclimate was teleconnected strongly to the overall global cooling pattern, so that local enhanced aridification recorded by the studied aeolian sequence is dominantly a response to global climatic forcing rather than plateau uplift.

Seroepidemiological and biomolecular survey on Toxoplasma gondii infection on organic pig farms.

Pigs are an important reservoir of Toxoplasma gondii, and pork meat is considered one of the main sources of human infection. The present survey assesses the prevalence of T. gondii in organically reared pigs in Sardinia found on the island using various diagnostic methods. Firstly, a seroepidemiological survey was carried out on 63 farms, examining individual blood samples from 414 adult pigs. Secondly, a biomolecular investigation carried out on another 62 farms, examining the brain samples from 107 adult pigs. The seroprevalence detected for T. gondii at the farm level was 85.7% (54 out of the 63 pig farms examined). However, the prevalence rate in the investigated pigs was 51.7% (214 positives out of 414 examined). A total of 54.8% (34/62) of the monitored pig farms were found to be positive by PCR. The presence of T. gondii DNA in individual brain samples was detected in 47.7% (51/107) of the examined animals. The high prevalence of T. gondii found is alarming and suggests that pigs reared on organic farms should be considered as a significant source of infection for humans in the areas investigated.

Pharmacokinetics of difloxacin in olive flounder Paralichthys olivaceus at two water temperatures.

In this study, the pharmacokinetics profiles of difloxacin in the olive flounder (Paralichthys olivaceus) were investigated following intravenous and oral administration (10 mg/kg BW) at 14 and 22 °C water temperatures. Plasma and tissue samples (muscle, liver, and kidney) were analyzed using an HPLC method. The results showed that the plasma concentration-time data for difloxacin were described commendably by two-compartment open model at the two water temperatures. The absorption half-life (t(1/2ka)) of difloxacin after oral administration were 2.08 and 1.10 h at 14 and 22 °C, respectively; whereas the elimination half-life (t(1/2ß)) was 4.41 and 2.38 h, respectively. The muscle concentration of 1.35 ± 0.19 µg/g was observed at 9 h at 14 °C, and 2.11 ± 0.33 µg/g at 6 h at 22 °C, respectively. For liver, the peak concentration of difloxacin 2.43 ± 0.30 µg/g occurred at 6 h at 14 °C, which was lower than the 3.34 ± 0.24 µg/g peak that occurred at 4 h at 22 °C. The calculated bioavailability of difloxacin was 68.07% at 22 °C, which was higher than the 53.43% calculated for 14 °C. After intravenous administration, the t(1/2ß) were 4.79 and 2.81 h at 14 and 22 °C, respectively. The results indicate that the peak concentrations in muscle and liver at 14 °C are approximately half of those achieved at 22 °C. However, the C(max) in kidney at 14 and 22 °C were similar. The Vd values were 1.20 and 1.75 L/kg at 14 and 22 °C, respectively. These data indicated that both temperature and drug administration had significant effects on the elimination of difloxacin, and lower temperature or oral administration resulted in lower elimination.

Chitinolytic activity of endophytic Streptomyces and potential for biocontrol.

AIMS: Biological sources for the control of plant pathogenic fungi remain an important objective for sustainable agricultural practices. Actinomycetes are used extensively in the pharmaceutical industry and agriculture owing to their great diversity in enzyme production. In the present study, therefore, we evaluated chitinase production by endophytic actinomycetes and the potential of this for control of phytopathogenic fungi. METHODS AND RESULTS: Endophytic Streptomyces were grown on minimum medium supplemented with chitin, and chitinase production was quantified. The strains were screened for any activity towards phytopathogenic fungi and oomycetes by a dual-culture in vitro assay. The correlation between chitinase production and pathogen inhibition was calculated and further confirmed on Colletotrichum sublineolum cell walls by scanning electron microscopy. CONCLUSIONS: This paper reports a genetic correlation between chitinase production and the biocontrol potential of endophytic actinomycetes in an antagonistic interaction with different phytopathogens, suggesting that this control could occur inside the host plant. SIGNIFICANCE AND IMPACT OF THE STUDY: A genetic correlation between chitinase production and pathogen inhibition was demonstrated. Our results provide an enhanced understanding of endophytic Streptomyces and its potential as a biocontrol agent. The implications and applications of these data for biocontrol are discussed.