Synthetic microbial consortia: from systematic analysis to construction and applications.

Synthetic biology is an emerging research field that focuses on using rational engineering strategies to program biological systems, conferring on them new functions and behaviours. By developing genetic parts and devices based on transcriptional, translational, post-translational modules, many genetic circuits and metabolic pathways had been programmed in single cells. Extending engineering capabilities from single-cell behaviours to multicellular microbial consortia represents a new frontier of synthetic biology. Herein, we first reviewed binary interaction modes of microorganisms in microbial consortia and their underlying molecular mechanisms, which lay the foundation of programming cell-cell interactions in synthetic microbial consortia. Systems biology studies on cellular systems enable systematic understanding of diverse physiological processes of cells and their interactions, which in turn offer insights into the optimal design of synthetic consortia. Based on such fundamental understanding, a comprehensive array of synthetic microbial consortia constructed in the last decade were reviewed, including isogenic microbial communities programmed by quorum sensing-based cell-cell communications, sender-receiver microbial communities with one-way communications, and microbial ecosystems wired by two-way (bi-directional) communications. Furthermore, many applications including using synthetic microbial consortia for distributed bio-computations, chemicals and bioenergy production, medicine and human health, and environments were reviewed. Synergistic development of systems and synthetic biology will provide both a thorough understanding of naturally occurring microbial consortia and rational engineering of these complicated consortia for novel applications.

Engineering a Pseudomonas putida as living quorum quencher for biofilm formation inhibition, benzenes degradation, and environmental risk evaluation.

Bacterial communication interruption based on quorum quenching (QQ) has been proven its potential in biofilm formation inhibition and biofouling control. However, it would be more satisfying if QQ could be combined with the efficient degradation of contaminants in environmental engineering. In this study, we engineered a biofilm of Pseudomonas putida through introducing a QQ synthetic gene, which achieved both biofilm formation inhibition and efficient degradation of benzene series in wastewater. The aiiO gene introduced into the P. putida by heat shock method was highly expressed to produce QQ enzyme to degrade AHL-based signal molecules. The addition of this engineered P. putida reduced the AHLs concentration, quorum sensing gene expression, and connections of the microbial community network in activated sludge and therefore inhibited the biofilm formation. Meanwhile, the sodium benzoate degradation assay indicated an enhanced benzene series removal ability of the engineering bacteria on activated sludge. Besides, we also demonstrated a controllable environmental risk of this engineered bacteria through monitoring its abundance and horizontal gene transfer test. Overall, the results of this study suggest an alternative strategy to solve multiple environmental problems through genetic engineering means and provide support for the application of engineered bacteria in environmental biotechnology.

Effect of High Suspension and Low Incision Surgery Based on Traditional Ligation of Chinese Medicine in Treatment of Mixed Haemorrhoids: A Multi-centre, Randomized, Single-Blind, Non-inferiority Clinical Trial.

OBJECTIVE: To observe the clinical effect of high suspension and low incision (HSLI) surgery on mixed haemorrhoids, compared with Milligan-Morgan haemorrhoidectomy. METHODS: A multi-centre, randomized, single-blind, non-inferiority clinical trial was performed. Participants with mixed haemorrhoids from Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing Rectum Hospital, Air Force Medical Center of People's Liberation Army of China, and Puyang Hospital of Traditional Chinese Medicine were enrolled from September 2016 to March 2018. By using a blocked randomization scheme, participants were assigned to two groups. The experimental group was treated with HSLI, while the control group was treated with Milligan-Morgan haemorrhoidectomy. The primary outcome was the clinical effect evaluated at 12 weeks after operation. The secondary outcomes included the number of haemorrhoids treated during the operation, pain scores, use of analgesics, postoperative oedema, wound healing, incidence of anal stenosis, anorectal manometry after operation, as well as surgical duration, length of stay and total hospitalization expenses. A safety evaluation was also conducted. RESULTS: In total, 246 eligible participants were enrolled, with 123 cases in each group. There was no significant difference in the clinical effect between the two groups (100.00% vs. 99.19%, P>0.05). Compared with the control group, the number of external haemorrhoids treated during the operation and the pain scores after operation were significantly reduced in the experimental group (P<0.05 or P<0.01); the patient number with wound healing at 2 weeks after operation and the functional length of anal canal at 12 weeks after operation were significantly increased in the experimental group (P<0.05). There was no significant difference in the incidence of anal stenosis, the numbers of patients using analgesics and patients with postoperative oedema between the two groups after operation (P>0.05). The surgical duration and length of stay in the experimental group were significantly longer than those in the control group, and the total hospitalization expense was significantly higher than that in the control group (all P<0.05). No adverse events were reported in either group during the whole trial or follow-up period. CONCLUSION: HSLI had the advantages of preserving the skin of anal canal completely, alleviating postsurgical pain and promoting rapid recovery after operation. (Registration No. ChiCTR1900022883).

Biodegradation of crude oil by a newly isolated strain Rhodococcus sp. JZX-01.

A highly efficient oil-degrading bacteria JZX-01 was isolated from the oil-contaminated soil of the seacoast near the Boxi Offshore Oil Field of China. Morphological, physiological, and 16S rDNA gene sequence analyses indicated that JZX-01 was assigned to the genus Rhodococcus sp. This strain decomposed 65.27 ± 5.63 % of the crude oil in 9 days. Gas chromatography-mass spectrometry analysis showed that even the long-chain hydrocarbons (C31-C38) and branched alkanes (pristine and phytane), which were regarded as the stubborn ones, could be degraded. Further study showed that the bacteria still has good oil degradation ability at low temperatures as well as under high salt conditions. Moreover, JZX-01 was found to have a biosurfactant-producing capacity, which significantly favors the surface tension reduction and crude oil degradation. The promising isolated strain Rhodococcus sp. JZX-01 could be further used for the bioremediation of oil-polluted soil or seawater in a wide range of temperatures and high salt conditions.

[Co-metabolism of dual culture in the degradation of phenolic compounds].

The biodegradation of phenol, m-cresol and 4-chlorophenol by the pure and mixed culture of Pseudomonas putida and Candida tropicalis was investigated. The results showed that,with the initial concentrations of 100, 50 and 60 mg x L(-1) for phenol, m-cresol and 4-chlorophenol, respectively,and an increase in the absolute value of the kinetic constant k of 19.0%, 2.6% and 46.4% for the degradation of phenol, m-cresol and 4-chlorophenol, respectively, was reached by dual culture compared with pure culture. The activity assays of phenol hydroxylase and catechol 1, 2-dioxygenase demonstrated phenol was degraded via the ortho-cleavage pathway in both of the two species. Further experiments via high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry techniques (LC-MS) suggested the degradation of three phenolic compounds could be accelerated due to co-metabolism by Pseudomonas putida of cis, cis-muconic acid, and 4-carboxymethylenebut-2-en-4-olide accumulated in phenol and 4-chlorophenol degradation, respectively, 3, 4-dihydroxybenzoic acid, 2-maleylacetate, and 3-oxoadipate in the degradation of m-cresol by Candida tropicalis in dual culture.

[Epidemiologic study on patients with invasive fungal infections].

OBJECTIVE: To investigate the epidemiological features of patients with nosocomial invasive fungal infection. METHODS: Fungi in blood were identified by BacT ALERT 3D, other clinical samples were cultured by Sabouraud's dextrose agar (SDA) medium. Candidas were isolated and identified by CHRO Magar candida color medium. Fungus-cultured positive cases from Jan. 2004 to Nov. 2007 were analyzed on items as patients' age, underlying disease, sample, strain, and species distribution. All statistical analyses were carried out by SPSS 13.0. RESULTS: The overall incidence rate of invasive fungal infections was 4.12%. The average age of patients was 7 - 96 with most patients were male, with geriatric problems and different kinds of underlying diseases. Lower respiratory tract infection was the most frequent infection site, followed by urinary tract, gastrointestinal tract. The main pathogens of invasive fungal infections were Candidas (93.80%). Strains of Candida albicans were the most frequent organisms which accounted for 67.29% of all the isolates. Mould fungus infections accounted for only 6.20%. During the 4 years of observation, the detection rate of fungi, specimen sources and the distribution of species and compartment were different with significant differences (P < 0.0083). CONCLUSION: The epidemiological properties such as the source of specimen, the distribution of species and composition sections of invasive fungal infections were changing. Candida spp. were still the main pathogens of invasive fungal infections but the sections of fungi changed. The incidence of Aspergillus infections had been increasing recently.