Characterization of a Panel of Constitutive Promoters from Lactococcus cremoris for Fine-Tuning Gene Expression.

Lactococcus cremoris (homotypic synonym: Lactococcus lactis) is receiving increasing attention as a prominent vehicle for the delivery of live vaccines. This can hardly be achieved without developing tools for the genetic manipulation of L. cremoris, and the paucity of studies on L. cremoris endogenous promoters has attracted our attention. Here, we report the discovery and characterization of 29 candidate promoters identified from L. cremoris subsp. cremoris NZ9000 by RNA sequencing analysis. Furthermore, 18 possible constitutive promoters were obtained by RT-qPCR screening from these 29 candidate promoters. Then, these 18 promoters were cloned and characterized by a reporter gene, gusA, encoding ß-glucuronidase. Eventually, eight endogenous constitutive promoters of L. cremoris were obtained, which can be applied to genetic manipulation of lactic acid bacteria.

A case report of autoimmune GFAP astrocytopathy presenting with abnormal heart rate variability and blood pressure variability.

BACKGROUND: Autonomic dysfunctions including bladder dysfunction, gastrointestinal dysfunction and orthostasis are common symptoms of autoimmune glial fibrillary acidic protein astrocytopathy (A-GFAP-A); however, cardiac autonomic dysfunction and abnormal circadian rhythm of blood pressure, which can lead to poor prognosis and even sudden cardiac death, has never been reported in A-GFAP-A patient. CASE PRESENTATION: A 68-year-old male Chinese patient presented to our hospital with headache, fever, progressive disturbance of consciousness, dysuria, and limb weakness. Abnormal heart rate variability and non-dipper circadian rhythm of blood pressure gradually developed during hospitalization, which is rare in A-GFAP-A. He had positive GFAP IgG in cerebrospinal fluid (CSF). Enhanced brian MRI showed uneven enhancement and T2 hyperintense lesions of medulla oblongata; Cervical spine MRI showed T2 hyperintense lesions in medulla oblongata and upper margin of the T2 vertebral body. A contrast-enhanced thoracic spine MRI showed uneven enhancement and T2 hyperintense lesions of T1 to T6 vertebral segments. After treatment with intravenous immunoglobulin and corticosteroids, the patient's symptoms, including autonomic dysfunction, alleviated dramatically. Finally, his heart rate variability and blood pressure variability became normal. CONCLUSIONS: Our case broadens the spectrum of expected symptoms in A-GFAP- A syndromes as it presented with heart rate variability and blood pressure variability.

The Arginine Repressor ArgR2 Controls Conjugated Linoleic Acid Biosynthesis by Activating the cla Operon in Lactiplantibacillus plantarum.

CLA (conjugated linoleic acid) has attracted substantial attention due to its physiological functions, including regulating immunity, reducing obesity, and contributing to cancer suppression. In Lactiplantibacillus plantarum, CLA oleate hydratase (CLA-HY), CLA short-chain dehydrogenase (CLA-DH), and CLA acetoacetate decarboxylase (CLA-DC) catalyze the biotransformation of linoleic acid (LA) to CLA. However, the underlying transcriptional regulation mechanism of this pathway remains largely unknown. In this study, the potential transcriptional regulators that might bind to the cla promoter of L. plantarum AR195 were investigated by DNA pulldown. Interestingly, ArgR2, the transcriptional regulator of arginine metabolism, was identified as a potential regulator involved in the regulation of CLA biotransformation. Electrophoretic mobility shift assay (EMSA) and molecular interaction results demonstrated the specific binding of ArgR2 to the regulatory region of the cla operon. The knockout of argR2 led to the downregulation of cla-dh and cla-dc by 91% and 34%, respectively, resulting in a decline in the CLA yield by 14%. A segmental EMSA revealed that ArgR2 bound to three distinct sites in the cla regulatory region, and these binding sites were highly conserved and rich in AT. The regulatory mechanism of ArgR2 on CLA biosynthesis further expanded our knowledge of the regulatory mechanism of CLA biosynthesis in L. plantarum and laid the theoretical foundation for the production and application of CLA. IMPORTANCE CLA (conjugated linoleic acid) has received extensive attention owing to its important physiological functions. CLA from natural sources is far from meeting people's demands. Lactic acid bacteria can efficiently synthesize cis-9,trans-11-CLA and trans-10,cis-12-CLA, which possess physiological activities. However, little is known about the regulatory mechanism. In this study, we identified that the biosynthesis of CLA in L. plantarum AR195 was transcriptionally regulated by the arginine biosynthesis regulatory protein ArgR2. The regulation mechanism of ArgR2 on CLA biosynthesis lays a theoretical foundation for the regulation of CLA synthesis and industrial production.

Determination of the regulatory network and function of the lysR-type transcriptional regulator of Lactiplantibacillus plantarum, LpLttR.

BACKGROUND: Lactiplantibacillus plantarum has various healthcare functions including the regulation of immunity and inflammation, reduction of serum cholesterol levels, anti-tumor activity, and maintenance of the balance of intestinal flora. However, the underlying metabolic and regulatory mechanisms of these processes remain unclear. Our previous studies have shown that the LysR type transcriptional regulator of L. plantarum (LpLttR) regulates the biotransformation of conjugated linoleic acids (CLAs) through the transcriptional activation of cla-dh (coding gene for CLA short-chain dehydrogenase) and cla-dc (coding gene for CLA acetoacetate decarboxylase). However, the regulatory network and function of LpLttR have not yet been characterized in L. plantarum. RESULTS: In this study, the regulatory role of LpLttR in various cellular processes was assessed using transcriptome analysis. The deletion of LpLttR had no evident influence on the bacterial growth. The transcriptome data showed that the expression of nine genes were positively regulated by LpLttR, and the expression of only two genes were negatively regulated. Through binding motif analysis and molecular interaction, we demonstrated that the regulatory region of the directly regulated genes contained a highly conserved sequence, consisting of a 15-base long box and rich in AT. CONCLUSION: This study revealed that LpLttR of L. plantarum did not play a global regulatory role similar to that of the other transcriptional regulators in this family. This study broadens our knowledge of LpLttR and provides a theoretical basis for the utilization of L. plantarum.

LysR Family Regulator LttR Controls Production of Conjugated Linoleic Acid in Lactobacillus plantarum by Directly Activating the cla Operon.

Conjugated linoleic acids (CLAs) have attracted more attention as functional lipids due to their potential physiological activities, including anticancer, anti-inflammatory, anti-cardiovascular disease, and antidiabetes activities. Microbiological synthesis of CLA has become a compelling method due to its high isomer selectivity and convenient separation and purification processes. In Lactobacillus plantarum, the generation of CLA from linoleic acids (LAs) requires the combination of CLA oleate hydratase (CLA-HY), CLA short-chain dehydrogenase (CLA-DH), and CLA acetoacetate decarboxylase (CLA-DC), which are separately encoded by cla-hy, cla-dh, and cla-dc. However, the regulatory mechanisms of CLA synthesis remain unknown. In this study, we found that a LysR family transcriptional regulator, LTTR, directly bound to the promoter region of the cla operon and activated the transcription of cla-dh and cla-dc. The binding motif was also predicted by bioinformatics analysis and verified by electrophoretic mobility shift assays (EMSAs) and DNase I footprinting assays. The lttR overexpression strain showed a 5-fold increase in CLA production. Moreover, we uncovered that the transcription of lttR is activated by LA. These results indicate that LttR senses LA and promotes CLA production by activating the transcription of cla-dh and cla-dc. This study reveals a new regulatory mechanism in CLA biotransformation and provides a new potential metabolic engineering strategy to increase the yield of CLA.IMPORTANCE Our work has identified a novel transcriptional regulator, LTTR, that regulates the production of CLA by activating the transcription of cla-dh and cla-dc, essential genes participating in CLA synthesis in Lactobacillus plantarum This study provides insight into the regulatory mechanism of CLA synthesis and broadens our understanding of the synthesis and regulatory mechanisms of the biosynthesis of CLA.

Antrodin A from mycelium of Antrodia camphorata alleviates acute alcoholic liver injury and modulates intestinal flora dysbiosis in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Antrodia camphorata (A. camphorata) is a rare functional fungus in Taiwan and contains a variety of biologically active ingredients. Antrodin A (AdA) is one of the main active ingredients in the solid-state fermented A. camphorata mycelium. It protects the liver from alcohol damage by improving the antioxidant and anti-inflammatory capacity of the liver and maintaining the stability of the intestinal flora. AIM OF THE STUDY: The aim of this study was to evaluate the hepatoprotective activities of ethyl acetate layer extract (EALE), AdA, and Antroquinonol (Aq) from mycelium of A. camphorata on alcoholic liver injury. MATERIALS AND METHODS: Mice were given with intragastrically vehicle (NC, 2% CMC-Na), alcohol (AL, 12 mL/kg bw), or different A. camphorata samples (EALE, AdA, Aq) at low (100 mg/kg bw) or high (200 mg/kg bw) dosages. The positive control (PC) group was given with silymarin (200 mg/kg bw). Except the NC group, each group of mice was fasted for 4 h after the last treatment and was intragastrically administrated with 50% alcohol (12 mL/kg bw). At the end of experiment, mouse serum was collected and the liver was excised. A portion of the liver was fixed in formalin and used for histopathological analysis, whereas the rest was used for biochemical analysis and real-time PCR analysis. The intestinal flora structure of feces was analyzed by determining the v3-v4 region sequence in 16S rDNA. RESULTS: The high-dose groups of the three samples (EALEH, AdAH, and AqH) significantly alleviated the alcohol-induced increases in liver index, serum ALT, AST, and AKP activities. Serum TG level was significantly reduced in all treatment groups. The increase of HDL-C content indicated that active ingredients of A. camphorata could reduce the lipid content in serum. Furthermore, MDA contents of the AdAH and AqH groups in liver were significantly reduced, accompanying with the levels of SOD, CAT, and GSH elevated to various extents. Antioxidant and anti-inflammatory capabilities in the liver were increased in the AdAH group, as evidenced by the mRNA expression levels of Nrf-2 and HO-1 were significantly increased; while those of CYP2e1, TNF-α, and TLR-4 were significantly decreased. Analysis of intestinal flora of feces showed that alcohol treatment significantly changed the composition of intestinal flora. Supplementation with AdA could mitigate dysbiosis of intestinal flora induced by alcohol. Flora of Faecalibaculum, Lactobacillus, and Coriobacteriaceae_UCG-002 showed significantly negative correlations with ALT, AST, AKP, and MDA levels. CONCLUSION: Antrodin A could improve the antioxidant and anti-inflammatory capacities of the liver and maintain the stability of intestinal flora. It is potentially a good candidate compound against acute alcoholic liver injury.

Influence of freezing temperature before freeze-drying on the viability of various Lactobacillus plantarum strains.

Although freeze-drying is an excellent method for preserving microorganisms, it inevitably reduces cell activity and function. Moreover, probiotic strains differ in terms of their sensitivity to the freeze-drying process. Therefore, it is necessary to optimize the variables relevant to this process. The pre-freezing temperature is a critical parameter of the freeze-drying process, but it remains unclear whether the optimal pre-freezing temperature differs among strains and protectants. This study explored the effects of 4 different pre-freezing temperatures on the survival rates of different Lactobacillus plantarum strains after freeze-drying in the presence of different protectants. Using phosphate-buffered saline solution and sorbitol as protectants, pre-freezing at -196°C, -40°C, and -20°C ensured the highest survival rates after freeze-drying for AR113, AR307, and WCFS1, respectively. Using trehalose, pre-freezing at -20°C ensured the best survival rate for AR113, and -60°C was the best pre-freezing temperature for AR307 and WCFS1. These results indicate that the pre-freezing temperature can be changed to improve the survival rate of L. plantarum, and that this effect is strain-specific. Further studies have demonstrated that pre-freezing temperature affected viability via changes in cell membrane integrity, membrane permeability, and lactate dehydrogenase activity. In summary, pre-freezing temperature is a crucial factor in L. plantarum survival after freeze-drying, and the choice of pre-freezing temperature depends on the strain and the protectant.

Isolation of biogenic amine-negative lactic acid bacteria for Chinese rice wine fermentation based on molecular marker reverse screening.

BACKGROUND: Chinese rice wine (CRW; a traditional alcoholic beverage in China with unique flavor and high nutritional value) containing high level of biogenic amines (BAs) may be deleterious to human health. The processes of rice soaking, primary fermentation and secondary fermentation were found to be the major factors for accumulation of BAs during industrial CRW production. RESULTS: To reduce the risk of the formation of BAs in CRW production, Enterococcus durans AR315, a BA-negative lactic acid bacterium, was isolated from CRW samples by PCR-based molecular marker reverse screening in this work. With addition of AR315 during steeping rice phase, the level of total BAs was significantly decreased by 45.1% in comparison with the control. Moreover, the final BA concentration with the addition of AR315 was 27.6% lower than that of the control during fermentation phase. CONCLUSIONS: To our knowledge, this is the first report of decreased accumulation of BAs in CRW production using a BA-negative lactic acid bacterium. Hence, using a BA-negative lactic acid bacterium as a starter culture could be an efficient strategy for significantly reducing the formation of BAs, which has the potential for industrial application in CRW production. © 2020 Society of Chemical Industry.

Topological chiral crystals with helicoid-arc quantum states.

The quantum behaviour of electrons in materials is the foundation of modern electronics and information technology1-11, and quantum materials with topological electronic and optical properties are essential for realizing quantized electronic responses that can be used for next generation technology. Here we report the first observation of topological quantum properties of chiral crystals6,7 in the RhSi family. We find that this material class hosts a quantum phase of matter that exhibits nearly ideal topological surface properties originating from the crystals' structural chirality. Electrons on the surface of these crystals show a highly unusual helicoid fermionic structure that spirals around two high-symmetry momenta, indicating electronic topological chirality. The existence of bulk multiply degenerate band fermions is guaranteed by the crystal symmetries; however, to determine the topological invariant or charge in these chiral crystals, it is essential to identify and study the helicoid topology of the arc states. The helicoid arcs that we observe on the surface characterize the topological charges of ±2, which arise from bulk higher-spin chiral fermions. These topological conductors exhibit giant Fermi arcs of maximum length (π), which are orders of magnitude larger than those found in known chiral Weyl fermion semimetals5,8-11. Our results demonstrate an electronic topological state of matter on structurally chiral crystals featuring helicoid-arc quantum states. Such exotic multifold chiral fermion semimetal states could be used to detect a quantized photogalvanic optical response, the chiral magnetic effect and other optoelectronic phenomena predicted for this class of materials6.

Functional analysis and heterologous expression of bifunctional glutathione synthetase from Lactobacillus.

Bifunctional glutathione synthetase (GshF) has recently been reported to simultaneously catalyze the 2-step ATP-dependent biosynthesis of reduced glutathione (GSH). In this work, 19 putative gshF were mined from the complete sequenced genome of 20 representative Lactobacillus species. To functionally analyze these putative GshF, GshF from Lactobacillus plantarum and Lactobacillus casei were selected and successfully expressed in Escherichia coli. Compared with the control without expressing GshF, GSH titers were enhanced significantly in E. coli with overexpression of GshF, demonstrating that putative GshF from Lactobacillus have functional activities on GSH biosynthesis. Moreover, with the expression of GshF from L. plantarum in E. coli as a paradigm, GSH yield (286.5 µM) was strongly improved by 177.9% with optimized induced conditions and precursor concentration compared with the control under unoptimized conditions. Transcriptional analysis showed that key genes of endogenous GSH metabolism and precursor biosynthesis were remarkably suppressed by GshF expression, indicating that the increase of GSH titer was attributed to heterologous expression of GshF. Overall, our results suggested that gshF is enriched in Lactobacillus and that heterologous expression of GshF is an efficient strategy for improving GSH biosynthesis.

Short communication: Improving the activity of bile salt hydrolases in Lactobacillus casei based on in silico molecular docking and heterologous expression.

Bile salt hydrolase (BSH) plays an essential role in the cholesterol-removing effect of lactic acid bacteria, which hydrolyze conjugated bile salts to amino acid and deconjugated bile salts. However, Lactobacillus casei lacks the bsh gene, which may make it highly sensitive to bile salt stress. We wanted to improve the BSH activity of L. casei for various food-industry applications (e.g., milk fermentation). Plate assay testing indicated that Lactobacillus plantarum AR113 has the highest BSH activity. We cloned and sequenced 4 bsh genes from the genome of L. plantarum AR113. Structure modeling and molecular docking of BSH indicated that BSH1 and BSH3 could react efficiently with bile salts, so we selected BSH1 and BSH3 for heterologous expression in L. casei. Compared with single expression of BSH1 or BSH3, co-expression of both protein sequences showed the highest hydrolysis activity by HPLC analysis. Our results suggested that heterologous expression of BSH in L. casei can significantly improve host activity against bile salts, and in silico molecular docking could be an efficient method of rapid screening for BSH with high activity.

Anti-inflammation effects of corn silk in a rat model of carrageenin-induced pleurisy.

Pleurisy is an inflammation of the pleural layers that surround the lungs. Despite much research into inflammatory diseases, no drugs with favorable safety profiles are available yet for their treatment. Corn silk has been used in many parts of the world for the treatment of edema, cystitis, gout, kidney stones nephritis, and prostitutes. However, no scientific reports on the anti-inflammatory effects of corn silk were so far available. To test the anti-inflammatory efficacy of corn silk extract (CSEX) in a rat model of carrageenin (Cg)-induced pleurisy, exudate formation, and cellular infiltration, tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1ß), vascular endothelial growth factor alpha (VEGF-α), interleukin-17 (IL-17), C3 and C4 complement protein levels, adhesion molecule (ICAM-1) and inducible nitric oxide synthase (iNOS) levels, nuclear factor kappa B (NF-κB) activation, and total antioxidant activity were studied, respectively. Pretreatment with CSEX reduced Cg-induced pleurisy exudate, number of leukocytes, oxidative stress, C3 protein level, and O (2)(-) levels at the inflammatory site. Pretreatment with CSEX also inhibited TNF-α, IL-1ß, VEGF-α, and IL-17A and blocked inflammation-related events (ICAM-1 and iNOS) by activation of NF-κB. Supplementation with CSEX may be a promising treatment for inflammatory diseases that involve oxidative stress.

Trace elements analysis of urine and hair in tuberculous pleurisy.

In this study, copper, zinc, magnesium, manganese, selenium, and iron of urine and hair were measured in the patients with tuberculous (TB) pleurisy (n = 24) and in the control group (n = 20). Selenium, magnesium, and zinc of hair were found to be significantly lower in TB pleurisy cases than those in the control group (p < 0.05, p < 0.001, and p < 0.01, respectively). On the contrary, selenium and magnesium of urine were found to be significantly elevated in TB pleurisy cases than those in the control group (p < 0.05 and p < 0.001, respectively). There was no significant difference in the value of manganese and iron between TB pleurisy and the control group (p > 0.05). Copper level were significantly increased in hair and decreased in urine of the patients (p < 0.01). The occurrence of these abnormalities constitutes new information regarding trace elements in TB pleurisy patients. These results may provide an additional disease correlate for assessing TB pleurisy risk.

Serum trace element levels in tuberculous pleurisy.

In this study, copper, zinc, magnesium, manganese, selenium, and iron were measured by inductively coupled plasma atomic emission spectrophotometry in patients with tuberculous (TB) pleurisy (n = 24) and in the control group (n = 20). Selenium, magnesium, and zinc were found to be significantly lower in TB pleurisy cases than those in the control group (p < 0.01, p < 0.001, and p < 0.001, respectively). There was no significant difference in the value of manganese and iron between TB pleurisy and the control group (p > 0.05). Copper levels were significantly increased in the serum of the patients (p < 0.0001). These results may provide an additional disease correlate for assessing TB pleurisy risk.

Synthesis of novel macrolide derivatives with imidazo[4,5-b]pyridinyl sulfur contained alkyl side chains and their antibacterial activity.

In an effort to find new antibiotics, a novel series of 14-membered macrolides with imidazo[4,5-b]pyridinyl sulfur contained alkyl side chains has been synthesized based on commercially available clarithromycin. Chemical transformation of hydroxy group at position C-3 afforded range of ketolides and acylides. Compared to telithromycin, compound 15a demonstrated improved in vitro activity against erythromycin-susceptible and -resistant strains.

[Anti-HIV activities of Achyranthes bidentata polysaccharide sulfate in vitro and in vivo].

Achyranthes bidentata polysaccharide sulfate (ABPS) was a sulfated derivate derived from Achyranthes bidentata polysaccharide (ABP) which was isolated and identified from Chinese herb Achyranthes bidentata. The anti human immunodeficiency virus type 1 (HIV-1) activities were studied in vitro and in vivo. ABPS was found to inhibit HIV-1 reverse transcriptase and integrase with the 50% inhibiting concentration (IC60) of (2.948 +/- 0.556) micromol x L(-1) and (0.155 +/- 0.030) micromol x L(-1), respectively, but the parent compound ABP was not effective. ABPS inhibited HIV-1 P24 antigen with IC50 of (0.082 +/- 0.044) micromol x L(-1) and selective index (SI) of > (358 +/- 148) in MT-4 cell cultures acutely infected with HIV-1 IIIB virus, and with IC50 of (11.80 +/- 5.90) micromol x L(-1) and SI of > (24.2 +/- 12.1) in PBMC cell cultures acutely infected with clinical isolated zidovudine resistant HIV-1 virus, but there was no activity even at its concentration of 500 micromol x L(-1) in latent infection of H9/HIV-1 IIIB cell cultures. 5% sera taken from rats after intraperitoneal injection from rats with ABPS 125 mg x kg(-1) once or mice with 3 mg x kg(-1) qd for 20 days effectively inhibited HIV-1 P24 in MT-4 cell cultures, but those had no inhibitory effect when given orally. The results suggested that ABPS is a promising HIV-1 inhibitor, active on HIV-1 reverse transcriptase, integrase in vitro and HIV-1 P24 antigens in cell cultures, it was well absorbed by intraperitoneal injection but poor in oral bioavailability. It warrants further study.

Synthesis and antibacterial activity of 4''-O-heteroarylcarbamoyl derivatives of macrolide.

A series of novel 4''-position modified macrolide derivatives has been synthesized via a facile procedure. Their in vitro antibacterial activities against constitutively erythromycin-resistant strains were evaluated. Among the derivatives tested, compound 8a which has 11,12-carbamate and 4''-O-heteroarylcarbamoyl groups was found to have potent activity against most resistant bacteria.