Analysis of the complete genome sequence of Paenibacillus sp. lzh-N1 reveals its antagonistic ability.

BACKGROUND: Plant diseases caused by pathogenic fungi are devastating. However, commonly used fungicides are harmful to the environment, and some are becoming ineffective due to fungal resistance. Therefore, eco-friendly biological methods to control pathogenic fungi are urgently needed. RESULTS: In this study, a strain, Paenibacillus sp. lzh-N1, that could inhibit the growth of the pathogenic fungus Mycosphaerella sentina (Fr) Schrorter was isolated from the rhizosphere soil of pear trees, and the complete genome sequence of the strain was obtained, annotated, and analyzed to reveal the genetic foundation of its antagonistic ability. The entire genome of this strain contained a circular chromosome of 5,641,488 bp with a GC content of 45.50%. The results of species identification show that the strain belongs to the same species as P. polymyxa Sb3-1 and P. polymyxa CJX518. Sixteen secondary metabolic biosynthetic gene clusters were predicted by antiSMASH, including those of the antifungal peptides fusaricidin B and paenilarvins. In addition, biofilm formation-related genes containing two potential gene clusters for cyclic lactone autoinducer, a gene encoding S-ribosylhomocysteine lyase (LuxS), and three genes encoding exopolysaccharide biosynthesis protein were identified. CONCLUSIONS: Antifungal peptides and glucanase biosynthesized by Paenibacillus sp. lzh-N1 may be responsible for its antagonistic effect. Moreover, quorum sensing systems may influence the biocontrol activity of this strain directly or indirectly.

The Socio-demographic and Quality of Life of People Living with HIV (PLHIV) Presenting with Cutaneous Manifestation: A Cross-Sectional Study in the Department of Dermatology, Sarawak General Hospital

Background@#People living with Human Immunodeficiency Virus (PLHIV) are living longer with the advent of highly active antiviral therapy (HAART). Aside from extending the life span, quality of life is vital in PLHIV management. However, there is a paucity of data on the cutaneous manifestations in PLHIV on HAART. The objective of this study is to ascertain the prevalence of cutaneous manifestations, effect on daily lives, and relation to CD4 levels.@*Methods@#This is a prospective cross-sectional study comparing 2 groups of PLHIV patients on HAART and not on HAART therapy done from March 2020 to November 2020.@*Results@#A total of 259 patients were recruited in this study with a mean age of 40 years. There were 216 (83.4%) male and 43 (16.6 %) female. Men having sex with men accounts for 49%. The most common cutaneous disorder was post-inflammatory pigmentation (20.4%). Infective dermatoses were 43 (6.7%), and cutaneous malignancy 3 (0.6%). Mean DLQI in PLHIV on HAART were 2, as compared to PLHIV not on HAART which scored 3. Bidayuh ethnicity accounts for 30% of adverse drug reactions with Bactrim being the most common drug.@*Conclusion@#There is a high prevalence of dermatoses in PLHIV. HAART increases the CD4 count of patients thereby reducing the risk of opportunistic infection and related disorders. However, it did not reduce the cutaneous manifestations in PLHIV, as HAART itself may increase the risk of adverse cutaneous drug reactions. DLQI is not the best tool to assess quality of life.

The inhibition effects of Cu and Ni alloying elements on corrosion of HSLA steel influenced by Halomonas titanicae.

Halomonas titanicae accelerated steel corrosion by dissimilatory Fe(III) reduction under anaerobic environments, and their adhesion was the key to achieving extracellular electron transfer between cells and Fe(III). This work investigated the inhibition effects of Cu and Ni alloying elements on corrosion of high strength low alloy (HSLA) steel affected by H. titanicae. It was found that both the addition of Cu (1.3%) and high content of Ni (7.2%) brought better corrosion resistance than the steel containing 4.8% Ni via decreasing the amount of sessile bacterial cells. And the inhibition efficiency of Cu with the lower content was stronger than that of Ni with the higher content. Biofilm inhibition mechanisms varied from Cu to Ni alloying elements, and the former was achieved via bactericidal Cu ions released from steel. While for the HSLA steel with high Ni content, the formation of nickel oxides including NiFe2O4 and Ni(OH)2 refined the grains of corrosion products and decreased the bacterial attachment.

Exogenous autoinducer-2 inhibits biofilm development of Desulfovibrio sp. Huiquan2017.

Sulfate-reducing bacteria (SRB) are culprits for microbiologically influenced corrosion, and biofilms are believed to play essential roles in the corrosion induced by SRB. However, little is known about the regulation of SRB biofilms. Quorum sensing signal molecules acyl-homoserine lactones (AHLs) and autoinducer-2 (AI-2) regulate biofilm formation of many bacteria. In this study, the production of AHLs and AI-2 by one SRB strain, Desulfovibrio sp. Huiquan2017, was detected, and the effect of exogenous AI-2 on bacterial biofilm formation was discussed. It was found that the cell-free supernatants of Desulfovibrio sp. Huiquan2017 induced luminescence in a ∆luxS mutant strain Vibrio harveyi BB170, indicating the production of functional AI-2 by the bacterium. In the presence of exogenous AI-2, the growth of Desulfovibrio sp. Huiquan2017 and early biofilm formation were not affected, but the later stage of biofilm development was inhibited significantly. The biofilms became looser, smaller, and thinner, and contained less bacteria and extracellular polymeric substances (EPS). The inhibition effect of AI-2 on the biofilm development of Desulfovibrio sp. Huiquan2017 was mainly achieved through reducing the amount of EPS in biofilms. These findings shed light on the biofilm regulation of SRB.

Reducing the number of invalid surgical consents in the day surgery unit.

AIM: To reduce the number of invalid surgical consents in the Singapore National Eye Centre Day Surgery Unit over a period of 6 months. METHODOLOGY: A multidisciplinary team involving doctors, nurses, day surgery unit, operating theatre, listing and clinical audit staff looked into the listing process and the root causes of the high number of invalid consents. A Pareto chart detailing the top causes of invalid consents was drawn, and with a prioritisation matrix, feasible yet effective changes were identified and effected. Plan-Do-Study-Act (PDSA) cycles included moving consent checks upstream, getting invalid consents amended on the same day, sending emails to raise awareness on invalid consents and posters in clinics to emphasise the correct way to fill up consent forms. RESULT: There has been a progressive downtrend in the monthly mean percentage of invalid consents since the introduction of PDSA cycles. There was a significant reduction in the mean rate of rejected consents from the preintervention phase of 15.2% to the postintervention phase of 11.3%, shown with a Z score of 6.56 (P<0.05). Sustainability was also demonstrated with multiple consecutive points below the median of 14.5% on the postimplementation phase of the run chart, with estimated time-efficiency savings of USD$19 738.50 annually. CONCLUSION: Errors in the workplace can be reduced with a concerted effort from multiple stakeholders. It is important to have a thorough look at processes with concerned parties, so that different perspectives and skill sets can be harnessed to determine and implement feasible and effective interventions.

Oxygen Reduction Reaction Affected by Sulfate-Reducing Bacteria: Different Roles of Bacterial Cells and Metabolites.

Sulfate-reducing bacteria (SRB) were found to be capable of tolerating a certain amount of oxygen (O2), but how they affect oxygen reduction reaction (ORR) has not been clear. The present work investigated the impact of SRB on ORR in 3.5 wt% sodium chloride solution with the cyclic voltammetry method. The addition of SRB culture solution hampered both the reduction of O2 to superoxide (O2·-) and hydrogen peroxide (H2O2) to water (H2O), and the influence of SRB metabolites was much larger than that of bacterial cells. Sulfide and extracellular polymeric substances (EPS), typical inorganic and organic metabolic products, had great impact on ORR. Sulfide played an important role in the decrease of cathodic current for H2O2 reduction due to its hydrolysis and chemical reaction activity with H2O2. EPS were sticky, easy to adsorb on the electrode surface and abundant in functional groups, which hindered the transformation of O2 into O2·- and favored the reduction of H2O2 to H2O.

D-Phenylalanine inhibits biofilm development of a marine microbe, Pseudoalteromonas sp. SC2014.

D-Amino acids have been reported to be able to inhibit biofilm formation or disperse existing biofilms of many microbes; in some cases this is due to growth inhibition as an unspecific effect. In this work, six different D-amino acids were tested for their inhibitory effects on biofilm development and bacterial growth of Pseudoalteromonas sp. SC2014, a marine microbe involved in microbiologically influenced corrosion (MIC). Experimental results indicated that D-phenylalanine (D-Phe) inhibited biofilm formation effectively at concentrations that did not affect cell growth, whereas the other D-amino acids either showed little effect or inhibited biofilm formation while inhibiting bacterial growth. Further studies found that D-Phe could inhibit bacterial accumulation on the surface of 316L stainless steel, and prevent bacteria from forming a multilayer biofilm. It was also suggested that D-Phe could promote the disassembly of an established multilayer biofilm but have little effect on the remaining monolayer adherent cells. For the first time, it was found that a D-amino acid could effectively inhibit biofilm formation of an MIC-involved microbe. This might supply a new insight into how MIC could be mitigated.

Heterologous biosynthesis of costunolide in Escherichia coli and yield improvement.

Costunolide, the main bioactive compound of the medicinal plant, Radix Aucklandiae, is a sesquiterpene lactone (SL) and has a broad range of biological activities. It is also a precursor of many biologically-active SLs and is a branching point in the biosynthesis of SLs. Here we have reconstituted the costunolide biosynthetic pathway in Escherichia coli by co-expression of three genes (GAS, GAO, LsCOS) involved in costunolide biosynthesis and eight genes involved in converting acetyl-CoA into farnesyl diphosphate from mevalonate pathway. Costunolide production was then detected. By screening and optimization of cultured medium and inducing temperature, costunolide yield was up to 100 mg l(-1) in E. coli.

Subtle mutation detection of SMN1 gene in Chinese spinal muscular atrophy patients: implication of molecular diagnostic procedure for SMN1 gene mutations.

Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder caused by mutations of the survival of motor neuron 1 (SMN1) gene. Approximately 90-95% of SMA patients have a homozygous deletion of SMN1, and 5-10% of patients are believed to have subtle mutations. The molecular diagnosis of SMN1 subtle mutations is hampered by a highly homologous SMN2 gene. It is important to establish a rational molecular diagnostic procedure for SMN1 subtle mutations. We analyzed the SMN1 mutations in nine nonhomozygous patients by the following procedures: multiplex ligation-dependent probe amplification, genomic sequencing, T-A cloning on cDNA or genomic level, and/or real-time quantitative analysis. By the above molecular diagnostic procedure, six SMN1 subtle mutations, including c.5C>G(p.Ala2Gly), c.22_23 insA (p.Ser8LysfsX23), c.40G>T(p.Glu14X), c.43C>T(p.Gln15X), c.683T>A(p.Leu228X), and c.56delT(p.Val19GlyfsX21), were identified in nine Chinese patients. p.Glu14X has not been reported previously. Compared with the level of full-length SMN1 transcripts in the healthy carriers (14.1±4.5), the patient with p.Ala2Gly had no significant reduction (13.9±3.64, p=0.955). However, the levels in the patients carrying other mutations were significantly reduced (0.27±0.139 to 13.9±3.64, p=0.000-0.004). We present a reliable and rational diagnostic procedure for SMN1 subtle mutations, which would be helpful in molecular diagnosis of SMA compound heterozygotes. Our work extends the SMN1 mutation spectrum.

Deletion of intragenic tandem repeats in unit C of FLO1 of Saccharomyces cerevisiae increases the conformational stability of flocculin under acidic and alkaline conditions.

Flocculation is an attractive property for Saccaromyces cerevisiae, which plays important roles in fermentation industry and environmental remediation. The process of flocculation is mediated by a family of cell surface flocculins. As one member of flocculins, Flo1 is characterized by four families of repeats (designated as repeat units A, B, C and D) in the central domain. It is generally accepted that variation of repeat unit A in length in Flo1 influences the degree of flocculation or specificity for sugar recognization. However, no reports were observed for other repeat units. Here, we compared the flocculation ability and its sensitivity to environmental factors between yeast strain YSF1 carrying the intact FLO1 gene and yeast strains carrying the derived forms of FLO1 with partial or complete deletion of repeats in unit C. No obvious differences in flocculation ability and specificity of carbohydrate recognition were observed among these yeast strains, which indicates the truncated flocculins can stride across the cell wall and cluster the N-terminal domain on the surface of yeast cells as the intact Flo1 thereby improving intercellular binding. However, yeast strains with the truncated flocculins required more mannose to inhibit completely the flocculation, displayed broad tolerance of flocculation to pH fluctuation, and the fewer the repeats in unit C, the stronger adaptability of flocculation to pH change, which was not relevant to the position of deletion. This suggests that more stable active conformation is obtained for flocculin by deletion the repeat unit C in the central domain of Flo1, which was validated further by the higher hydrophobicity on the surface of cells of YSF1c with complete deletion of unit C under neutral and alkaline conditions and the stabilization of GFP conformation by fusion with flocculin with complete deletion of unit C in the central domain.

[Regulation of tandem repeats on the function of flocculation protein in Saccharomyces cerevisiae].

OBJECTIVE: There are a large numbers of tandem repeats in FLO1, which are highly dynamic components in genome leading to the unstable flocculation profiles in Saccharomyces cerevisiae. The effects of repeated unite B or D deletion on the function of flocculation protein was studied to provide theory basis for constructing genetically stable flocculation gene with minimal size. METHODS: We cloned the intact flocculation gene FLO1 from S. cerevisiae YS59 by PCR, and constructed the derived genes FLO1b and FLO1d with repeated unite B or D deletion respectively by fusion PCR. We analyzed the physiological characteristics of flocculation in yeast strains YSF1, YSF1b and YSF1d containing FLO1, FLO1b and FLO1d respectively. RESULTS: YSF1b and YSF1d displayed almost the same level of Flo1-type flocculation as YSF1. However, flocculation of YSF1b and YSF1d, especially YSF1d was more tolerant to pH change and mannose concentration than strain YSF1. CONCLUSION: Tandem repeats regulate the function of flocculation protein. Deletion of repeated unite B or D, especially D increases the stability of flocculation protein.