Journal of Microbiology and Biotechnology

1-7

Authors: Junjie Li

Compelling evidence suggests that histone deacetylase inhibitor (HDACi) influences the development of somatic cell nuclear transfer (SCNT) embryos. The current study was conducted to determine the effect of pretreatment of donor cumulus cells with Scriptaid (a novel HDACi) on cell cycle, histone acetylation and cloning embryos development in ovine. First, we optimized the efficiency of Scriptaid in a dose (0, 0.1, 0.2, 0.4 and 0.8 μmol/L) and time-dependent (0, 12, 24, 36, and 48 h) manner on the developmental capacity of these embryos. Then, we quantitatively assessed the alterations of acetylation levels in histone H3 lysine 9 (acH3K9) and histone H4 lysine 12 (acH4K12) of cumulus cells and SCNT embryos by immunofluorescence staining. Furthermore, we detected the proportion of G0/G1 phase cells in cumulus cells. We found a significantly improved blastocyst development rates of cloning embryos derived from donor cumulus cells pretreated with a mild dose (0.2 μmol/L) of Scriptaid for 24 hours (21/86 [24.39%] vs. 11/85 [12.91%]; P<0.05). Meanwhile, the levels of acH3K9 and acH4K12 were also improved significantly in cumulus cells and SCNT embryos (P<0.05). Moreover, more cumulus cells pretreated with Scriptaid were in G0/G1 phase compared with control group (84.22% vs. 75.96%, P<0.05). In conclusion, donor cumulus cells treated with Scriptaid is beneficial to early development of SCNT embryos, ascending acH3K9/ acH4K12 and G0/G1 phase cells proportion of cumulus cell. Scriptaid can be used to improve the efficiency of somatic cell nuclear transfer in ovine.

1-8

Authors: Su Xiao-jun

Two new isolates designated strain MY6 and strains FY2 were isolated from the mixture of fresh cow dung and fermentation biogas slurry, which were found to be potential cellulase producers. On the basis of cellular morphology, physiological and chemotaxonomic characteristics and similarity of 16S rDNA gene sequences, the former was confirmed as Stenotrophomonas sp., while the latter was identified as Bacillus cereus sp. Key fermentation factors including culture time, initial pH and culture temperature for cellulase production were optimized using single factor experiments for the two strains. The endoglucanase (CMCase) activity of MY6 was increased by 200.74% and reached 137.36 U/ml under the optimized conditions (cultured for 48 h at pH7.0 and 40°C with shaking at 160 rmp); while the activity of FY2 was enhanced by 150.61% and achieved 177.58 U/ml under the optimized conditions (cultured for 48 h at pH7.0 and 45°C with shaking at 160 rmp). The effects of four native lignocellulosic feed stocks on CMCase activities were compared. The results showed that cellulase from strains MY6 and FY2 were similar in cellulose degradation and the activity was strongest for filter paper, then for degreased cotton, straw powder and sawdust as substrates. These findings indicated that high cellulose concentration used as carbon sources could promote the generation of CMCase.

1-5

Authors: Jacques THIERIE

Analysis of the Luedeking-Piret model during the oxidative respiration to respirofermentative transition in a consortium grown in a chemostat revealed a significant increase in a parameter (β) of the Luedeking-Piret model in butyrate production. These data implied the possibility of improved capacity for cellular metabolites production under some culture conditions. Additionally, the parameter β was positively associated with a dilution rate above the critical dilution rate, suggesting the potential for enhancing industrial processes production using prokaryotes.

1-6

Authors: Zeng F

The interaction of microbial symbionts and Geocoris pallidipennis (Costa) was investigated. The study identified the microbial symbionts in the host insect, G.pallidipennis by 16S rDNA sequence analyses. The results showed that major symbiotic bacteria in G. pallidipennis were Wolbachia, Lactobacillus and Uncultured bacterium. The microbial symbionts in G. pallidipennis had significant effects on physiology and development of the host. The developmental times for 1st instar, 5th instar and preoviposition of G. pallidipennis in rifampin treatment (removal of microbial symbionts) were significantly longer compared with those of the control. In addition, female weight, average egg production per female each day and egg hatching rate in the treatment (removal of microbial symbionts) were significantly lower than those of the control. The results from current study indicate that the microbial symbionts in G. pallidipennis have significantly favorable effects on host physiology and promote the growth and fecundity of G. pallidipennis.

1-9

Authors: Xihui Shen

Corynebacterium glutamicum mycothiol peroxidase (MPx) is a novel CysGPx family peroxidase that uses both the mycoredoxin and thioredoxin reducing systems as proton donors for peroxide detoxification. In this study, we revealed that MPx is also important for cellular survival under acid stress. A Δmpx mutant exhibited significantly decreased resistance to acid stress and markedly increased accumulation of reactive oxygen species (ROS) and protein carbonylation levels in vivo. Overexpression of mpx increased the resistance of C. glutamicum to acid stress by reducing ROS accumulation. Elevated expression of the mpx gene was consistently observed when the C. glutamicum wild-type strain was exposed to acid stress conditions, which in turn directly contributed to tolerance to acid stress. The acid-induced expression of mpx was mediated by the stress-responsive extracytoplasmic function-sigma (ECF-σ) factor, SigH. The results unequivocally show that MPx is essential for combating acid stress by reducing intracellular ROS levels induced by acid stress in C. glutamicum, which adds a new dimension to the general physiological functions of CysGPx.

1-6

Authors: Dingxia Shen

Background: Compared with “classical” K. pneumoniae, hypervirulent variant of Klebsiella pneumoniae have the ability to cause serious, life-threatening community-acquired infection, including liver abscess, pneumonia, meningitis and endophthalmitis and the ability to metastatically spread. An objective diagnostic test suitable for routine use in the clinical microbiology laboratory is needed. Methods: A retrospective study was conducted in 240 patients with cultures positive for K. pneumoniae hospitalized in the Chinese PLA General Hospital from May 2013 to August 2014. The clinical and molecular data of the hypervirulent K. pneumoniae (hvKP) causing liver abscess were analyzed. Results: Among 240 strains of K. pneumoniae, hvKP accounted for 42.5% (102/240), hvKP causing liver abscess were 37 strains, accounting for 36.3% (37/102), patients with diabetes were 11 (11/37, 29.7%), 13 (13/37, 35.1%) patients were diagnosed as fever of unknown origin at first, 7(7/37, 18.9%) patients with tumor, the rest 6 (6/37, 16.2%) patients with postoperative infection or other site infection. Univariate analysis revealed the following risk factors for hvKP causing liver abscess: string test (odds ratio (OR), 11.306[95% confidence interval (CI), 3.579-35.711]), serotype K1 (OR, 3.109[95% CI, 1.338–7.222]) and fever of unknown origin (OR, 6.921[95% CI, 2.503–19.136]). The results detected by multiplex PCR were consistent with single PCR. 102 strains of hvKP were tested the sensitivity to 14-19 drug, 37 strains caused liver abscess were not found with ESBL. Conclusions: The detection of string test combined with rmpA and aerobactin can better identify hvKP. Patients with liver abscess generally were diabetes, but some patients didn’t have other disease. There is not much difference about the chance to be attacked by hvKP among male and female. ESBL was not detected among the hvKP causing liver abscess. Multiplex PCR assay could detect hvKP quickly.