Draft genome sequences of two protease-producing strains of <i>Arsukibacterium</i>, isolated from two cold and alkaline environments

Arsukibacterium ikkense GCM72(T) and a close relative, Arsukibacterium sp. MJ3, were isolated from two cold and alkaline environments as producers of extracellular proteolytic enzymes active at high pH and low temperature. This report describes the two draft genome sequences, which may serve as sources of future industrial enzymes

Genomic and exoproteomic analyses of cold- and alkaline-adapted bacteria reveal an abundance of secreted subtilisin-like proteases

Proteases active at low temperature or high pH are used in many commercial applications, including the detergent, food and feed industries, and bacteria specifically adapted to these conditions are a potential source of novel proteases. Environments combining these two extremes are very rare, but offer the promise of proteases ideally suited to work at both high pH and low temperature. In this report, bacteria from two cold and alkaline environments, the ikaite columns in Greenland and alkaline ponds in the McMurdo Dry Valley region, Antarctica, were screened for extracellular protease activity. Two isolates, Arsukibacterium ikkense from Greenland and a related strain, Arsukibacterium sp. MJ3, from Antarctica, were further characterized with respect to protease production. Genome sequencing identified a range of potential extracellular proteases including a number of putative secreted subtilisins. An extensive liquid chromatography–tandem mass spectrometry analysis of proteins secreted by A. ikkense identified six subtilisin‐like proteases as abundant components of the exoproteome in addition to other peptidases potentially involved in complete degradation of extracellular protein. Screening of Arsukibacterium genome libraries in Escherichia coli identified two orthologous secreted subtilisins active at pH 10 and 20°C, which were also present in the A. ikkense exoproteome. Recombinant production of both proteases confirmed the observed activity

Effect of an enzyme-containing mouthwash on the dental biofilm and salivary microbiome in patients with fixed orthodontic appliances : a randomized placebo-controlled pilot trial

BACKGROUND: Mouthwashes containing oral antiseptics or enzymes are suggested suitable for controlling biofilm accumulation in patients with fixed appliances and thereby limiting unwanted side effects during the orthodontic treatment. OBJECTIVES: To evaluate the effect of an enzyme-based mouthwash on the amount of dental biofilm and the composition of the salivary microbiome in patients undergoing treatment with fixed orthodontic appliances. TRIAL DESIGN: Randomized double-blind placebo-controlled trial. MATERIAL AND METHODS: In total, 35 young adolescents (14-18 years) under treatment with fixed appliances were consecutively enrolled and randomly allocated to an experimental or a placebo group by opening a computer-generated numbered envelope. The subjects were instructed to rinse twice daily during an intervention period of 8 days with experimental mouthwash or placebo without active enzymes. Unstimulated whole saliva samples were collected at baseline and after 8 days. The participants and examiner were blinded for the allocation. The primary outcome was the Orthodontic Plaque Index (OPI) and the secondary was the composition of the salivary microbiome. RESULTS: In total, 28 adolescents (21 females and 7 males) completed the trial and there were no differences in age, clinical, or microbial findings between the test (n = 14) and the placebo group (n = 14) at baseline. We found a decreased OPI in the test group after 8 days and the difference was statistically significant compared with the placebo group (P &lt; 0.05). There were no significant treatment effects on the richness and global composition of the salivary microbiome. HARMS: In total, one participant in the test group claimed nausea and abandoned the project. In total, two participants did not like the taste of the mouthwash but used it as instructed. No other adverse events or side effects were reported. LIMITATIONS: Short-term pilot trials may by nature be sensitive for selection and performance biases and are not designed to unveil persisting effects. CONCLUSION: Daily use of enzyme-containing mouthwash reduced the amount of dental biofilm in adolescents under treatment with the fixed orthodontic appliances, without affecting the composition of the salivary microbiota. ETHICAL APPROVAL: Approved by the Regional Ethical Board, Lund, Sweden (Dnr 2020-05221). CLINICAL TRIAL REGISTRATION: NCT05033015

Image-to-class distance ratio: A feature filtering metric for image classification

A growing number of complex features are designed to address various problems in computer vision. Feature selection is an efficient way to reduce the heavy computation cost caused by complex and lengthy features. The total features are substituted by a discriminative subset selected according to a criterion to reduce the dimensionality. In current feature selection methods, most of the subset selection metrics evaluate the features according to their relevance. However, the discriminative power of a feature subset is not simply determined by the relevance, especially in the case of complex features. In this paper, a new feature subset selection metric, the image-to-class distance ratio based on Euclidean distance, is proposed to select a subset in which the average intra-class Euclidean distance is minimized and average inter-class Euclidean distance is maximized, leading to good classification performance. In addition, the search space for feature selection problems with large-size complex features is huge, which makes many heuristic search methods infeasible. A Particle Swarm Optimization (PSO) based subset search algorithm is introduced to search the best subset according to the proposed metric in the huge search space. Experimental results show that the proposed subset search algorithm (I2CDRPSO) is effective. The feature subset selected by the metric has better performance than other feature selection metric in several classification methods

Fungal lysozyme leverages the gut microbiota to curb DSS-induced colitis

Colitis is characterized by colonic inflammation and impaired gut health. Both features aggravate obesity and insulin resistance. Host defense peptides (HDPs) are key regulators of gut homeostasis and generally malfunctioning in above-mentioned conditions. We aimed here to improve bowel function in diet-induced obesity and chemically induced colitis through daily oral administration of lysozyme, a well-characterized HDP, derived from Acremonium alcalophilum. C57BL6/J mice were fed either low-fat reference diet or HFD ± daily gavage of lysozyme for 12 weeks, followed by metabolic assessment and evaluation of colonic microbiota encroachment. To further evaluate the efficacy of intestinal inflammation, we next supplemented chow-fed BALB/c mice with lysozyme during Dextran Sulfate Sodium (DSS)-induced colitis in either conventional or microbiota-depleted mice. We assessed longitudinal microbiome alterations by 16S amplicon sequencing in both models. Lysozyme dose-dependently alleviated intestinal inflammation in DSS-challenged mice and further protected against HFD-induced microbiota encroachment and fasting hyperinsulinemia. Observed improvements of intestinal health relied on a complex gut flora, with the observation that microbiota depletion abrogated lysozyme’s capacity to mitigate DSS-induced colitis. Akkermansia muciniphila associated with impaired gut health in both models, a trajectory that was mitigated by lysozyme administration. In agreement with this notion, PICRUSt2 analysis revealed specific pathways consistently affected by lysozyme administration, independent of vivarium, disease model and mouse strain. Taking together, lysozyme leveraged the gut microbiota to curb DSS-induced inflammation, alleviated HFD-induced gastrointestinal disturbances and lowered fasting insulin levels in obese mice. Collectively, these data present A. alcalophilum-derived lysozyme as a promising candidate to enhance gut health