Identification, activity and delivery of new LysFA67 endolysin to target cheese spoilage Clostridium tyrobutyricum

Bacteriophages and their endolysins are potential biocontrol agents for the anaerobic spoilage organism Clostridium tyrobutyricum, which causes cheese late blowing defect. This study sequenced and compared the genomes of eight bacteriophages from Spanish dairy farms that were active against C. tyrobutyricum, to identify novel species and phage proteins. Phages vB_CtyS-FA67 and vB_CtyS-FA70 shared >94% intergenomic similarity to each other but neither phage had significant similarity to ΦCTP1, the unique C. tyrobutyricum phage sequenced to date. Taxonomic analysis indicated that both phages belong to the class Caudoviricetes and are related to dsDNA viruses with long non-contractile tails. vB_CtyS-FA67 had no other close relatives and encoded a novel endolysin, LysFA67, predicted to belong to the glycoside hydrolase GH24 family. LysFA67 lysed 93% of C. tyrobutyricum cells after 4 min in turbidity reduction assays, retaining lytic activity at pHs 4.2-8.1 and at 30-45 °C. The endolysin remained stable after 30 d storage at 4, 12 and 25 °C, while its activity decreased at -20 °C. LysFA67 lysed several clostridia species, while common dairy bacteria were not affected. Lactococcus lactis INIA 437, used as a cheese starter, was engineered to deliver LysFA67 and red fluorescent LysFA67-mCherry to dairy products. We demonstrated that these engineered strains were able to maintain lytic activity and fluorescence without affecting their technological properties in milk.

Isolation and characterization of new bacteriophages active against Clostridium tyrobutyricum and their role in preventing the late blowing defect of cheese

Lytic bacteriophages (phages) offer a great potential as biocontrol agents for spoilage Clostridium tyrobutyricum, responsible for butyric acid fermentation in semi-hard and hard ripened cheeses, resulting in late gas blowing defect. With this aim, we have isolated, identified and characterized new lytic phages of C. tyrobutyricum, and have evaluated their efficacy to control cheese late blowing by adding them to manufacture milk. Silage, soil, milk and cheese from dairy farms were screened for anti-clostridial phages, obtaining 96 isolates active against C. tyrobutyricum. According to host range, source and plaque morphology, we obtained 20 phage profiles, 8 of them (represented by phages FA3, FA21, FA29, FA52, FA58, FA67, FA70 and FA88) showing a wider host range and high quality lysis, which were further characterized. Selected isolates showed a non-contractile tail, belonging to the Siphoviridae family, and were grouped into 3 restriction profiles. Viable phages were detected after storage in sodium-magnesium buffer (SM buffer), skim milk and acidified skim milk (pH 5) for 7 d at 4 °C, 12 °C and 37 °C, although a decline in infectivity was observed in some cases. Good phage survival was also detected during semi-hard cheese manufacture and ripening (60 d), and cheese lactococci counts, pH, dry matter values, and volatile compounds were not affected by phage addition. In semi-hard cheese, phage FA67 impaired the early germination of C. tyrobutyricum spores and caused a significant decrease in clostridial vegetative cells counts at 14 d of ripening, delaying by 2 weeks the consumption of lactic acid, formation of butyric acid and appearance of late blowing symptoms, compared to the spoilt control cheese without the phage. This is the first report on the application of phage to control C. tyrobutyricum in cheese.

Venous Thromboembolism as an Initial Manifestation of COVID-19 in a Heart Transplant Patient

Introduction

The disease caused by the coronavirus 2019 (COVID-19) is mainly characterized by symptoms related to the upper respiratory tract associated with fever and constitutional symptoms, progressing in the most severe cases to pneumonia and severe acute respiratory syndrome (SARS). However, due to the increasing number of cases, atypical presentations have been found. Among them, thromboembolic manifestations stand out, since the virus itself seems to predispose to changes in the coagulation system.

Case Report

A 62-year-old male patient who underwent cardiac transplantation 6 months ago, secondary to chagasic cardiomyopathy, had pain and edema in his left foot for 1 week. Upon admission, he was eupneic, afebrile, heart rate of 96bpm, blood pressure of 120 × 70mmhg, with edema and erythema on his left foot. Chagas reactivation, cellulite or deep vein thrombosis were the diagnostic hypotheses suggested. Soft tissue ultrasound and venous doppler of the left lower limb were compatible with deep venous thrombosis and superficial thrombophlebitis. Skin lesion biopsy confirmed Chagas reactivation. Antibiotic therapy with cefazolin, full anticoagulation with enoxaparin and treatment with benzonidazole were introduced. In the second day of hospitalization, patient presented myalgia and dry cough, in addition to an increased C-reactive protein and multiple ground-glass opacities on computed tomography of the chest, suggestive of COVID-19. This finding was corroborated by a positive result of RT-PCR for SARS-COV2. The patient evolved with SARS, requiring progressive use of vasoactive drugs, mechanical ventilation and pronation.

Summary

It is currently known that COVID-19 increases the risk of thromboembolic events, especially in hospitalized patients, reaching an incidence of 25%, even in the presence of effective prophylaxis. Several mechanisms have been proposed for this association, but not with robust evidence. Despite these increased cases, there are no reports in the literature of initial presentation with a thromboembolic event in a heart transplant patient, emphasizing the importance of clinical suspicion and appropriate investigation.

AB0545 GASTROINTESTINAL INVOLVEMENT IN SYSTEMIC SCLEROSIS

Background:

Systemic sclerosis (SSc) is a chronic, connective tissue disease with an autoimmune pattern characterized by inflammation, fibrosis and microcirculation changes leading to internal organs malfunctions. The gastrointestinal tract (GIT) is affected in up to 90% of patients with SSc. Any part of the GIT from the mouth to the anus can be affected. There are few descriptive studies about SSc-related GIT involvement.

Objectives:

We aimed to characterize the GIT involvement in patients with SSc.

Methods:

This retrospective study included all patients from SSc cohort of our autoimmune diseases unit in a tertiary referral centre. All patients fulfilled SSc criteria proposed by the American College of Rheumatology. All subjects’ histories were evaluated. Laboratory and imaging results were obtained from the hospital files. Patients with digestive manifestations were compared with patients without GIT involvement. Chi2 and t-student were used, using the statistical package SPSS25.0.

Results:

83 subjects with SSc were included, 68 (81,9%) of them were women. The mean age at the onset of SSc was 62,1 ± 15,3 years (range 26-89) with a mean follow-up of 9,6 ± 7,4 years. 80,7% of patients had limited SSc, 12% diffuse SSc, 4.8% SSc sine scleroderma and 2,4% early SSc. Considering the immunological profile 12 (14,5%) had Scl70 antibodies, 49 (59%) anticentromere and 21 (25,3%) had ANA antibodies without specificity for anti-Scl70 or anticentromere. 37,3% patients had lung involvement, 20,5% scleroderma and 30,1% digital ulcers. 79,5% of SSc patients were treated with proton pump inhibitors or H2 blockers. 53 (63,9%) patients with SSc had GIT involvement. In 11 patients (20,7%) digestive involvement was diagnosed before SSc (mean 26,2 months). Esophageal involvement occurred in 83%, gastric involvement in 28,3%, intestine involvement in 24,5% and liver and biliary tree involvement in 26,4%. See table 1. No significant differences in age, sex, SSc subtype, autoantibody profile, lung involvement, skin disease, mortality and therapy were observed between patients with or without GIT manifestations. There were no deaths associated with GIT involvement. The most common pharmacologic therapy used was proton pump inhibitors (86,8%), domperidone (20,8%) and antibiotic rotation (17%).

EsophagealGastricIntestinalLiver and biliary tree44/53 (83%)15/53 (28,3%)12/53 (24,5%)14/53 (26,4%)Esophageal motility disorder 8 (15,1%)Gastroparesis 6 (11,3%)Small bacterial overgrowth 7 (13,2%)Primary biliary cholangitis 9 (17%)Gastroesophageal reflux 40 (75,5%)Abdominal pain /nausea 10 (18,9%)Colonic inertia 1 (1,9%)Autoimmune hepatitis 3 (5,7%)Dysphagia 11 (20,8%)Subacute gastritis 7 (13,2%)Diarrhea 6 (11,3%)Cholestatic liver enzymes 11 (20,8%)Flatulence / abdominal discomfort 6 (11,3%)Cirrhosis 2 (3,8%)

Conclusion:

Almost two thirds of our cohort of SSc have symptomatic gastrointestinal disease. GIT manifestations are heterogeneous. Symptoms are non-specific and overlapping for a particular anatomical site. Esophagus is the most commonly affected. More than seventy-five per cent of patients experience symptoms of gastroesophageal reflux. We did not find differences among patients with and without SSc GIT disease. 17% of patients had a Reynold’s syndrome.

References:

[1]Alastal Y et al. Gastrointestinal manifestations associated with systemic sclerosis: results from the nationwide inpatient simple. Ann Gastroenterol 2017; 30 (5): 1-6.

[2]Savarino E et al. Gastrointestinal motility disorder assessment in systemic sclerosis. Rheumatology. 2013; 52(6):1095–100.

[3]Steen VD et al. Severe organ involvement in systemic sclerosis with diffuse scleroderma. Arthritis and rheumatism. 2000; 43(11):2437–44.

Disclosure of Interests:

None declared

Difference in Electrochemical Mechanism of SnO2 Conversion in Lithium-Ion and Sodium-Ion Batteries: Combined in Operando and Ex Situ XAS Investigations

Conversion and alloying type negative electrodes attracted huge attention in the present research on lithium/sodium-ion batteries (LIBs/SIBs) due to the high capacity delivered. Among these, SnO₂ is investigated intensively in LIBs due to high cyclability, low reaction potential, cost-effectiveness, and environmental friendliness. Most of the LIB electrodes are explored in SIBs too due to expected similar electrochemical performance. Though several LIB negative electrode materials successfully worked in SIBs, bare SnO₂ shows very poor electrochemical performance in SIB. The reason for this difference is investigated here through combined in operando and ex situ X-ray absorption spectroscopy (XAS). For this, the electrodes of SnO₂ (space group P4₂/mnm synthesized via one-pot hydrothermal method) were cycled in Na-ion and Li-ion half-cells. The Na/SnO₂ half-cell delivered a much lower discharge capacity than the Li/SnO₂ half-cell. In addition, higher irreversibility was observed for Na/SnO₂ half-cell during electrochemical investigations compared to that for Li/SnO₂ half-cell. In operando XAS investigations on the Na/SnO₂ half-cell confirms incomplete conversion and alloying reactions in the Na/SnO₂ half-cell, resulting in poor electrochemical performance. The difference in the lithiation and sodiation mechanisms of SnO₂ is discussed in detail.

Use of fluorescent CTP1L endolysin cell wall-binding domain to study the evolution of Clostridium tyrobutyricum during cheese ripening

Clostridium tyrobutyricum is a bacteria of concern in the cheese industry, capable of surviving the manufacturing process and causing butyric acid fermentation and late blowing defect of cheese. In this work, we implement a method based on the cell wall-binding domain (CBD) of endolysin CTP1L, which detects C. tyrobutyricum, to monitor its evolution in cheeses challenged with clostridial spores and in the presence or absence of reuterin, an anti-clostridial agent. For this purpose, total bacteria were extracted from cheese samples and C. tyrobutyricum cells were specifically labelled with the CBD of CTP1L attached to green fluorescent protein (GFP), and detected by fluorescence microscopy. By using this GFP-CBD, germinated spores were visualized on day 1 in all cheeses inoculated with clostridial spores. Vegetative cells of C. tyrobutyricum, responsible for butyric acid fermentation, were detected in cheeses without reuterin from 30 d onwards, when LBD symptoms also became evident. The number of fluorescent Clostridium cells increased during ripening in the blowing cheeses. However, vegetative cells of C. tyrobutyricum were not detected in cheese containing the antimicrobial reuterin, which also did not show LBD throughout ripening. This simple and fast method provides a helpful tool to study the evolution of C. tyrobutyricum during cheese ripening.

Relevant electronic interactions related to the coordination chemistry of tetracyanometallates. An XPS study

In the K₂[M(CN)₄]·xH₂O (M = Ni, Pd, Pt) series, the CN ligand is found to donate electron density to the K ion, which is detected as a decrease in the K 2p BE. The charge donated is proportional to that removed from the inner metal (M) via π-back bonding.

Development of a specific fluorescent phage endolysin for in situ detection of Clostridium species associated with cheese spoilage

Late blowing defect (LBD) is a major cause of spoilage in cheeses, caused by the growth of Clostridium spp. in the cheese matrix. We investigated the application of CTP1L, a bacteriophage endolysin active against Clostridium tyrobutyricum, and its enzymatically active and cell wall-binding domains (EAD and CBD) attached to green fluorescent protein (GFP) to detect dairy-related Clostridium species by fluorescence microscopy. GFP-CTP1L and GFP-CBD demonstrated specificity for Clostridium spp. by labelling 15 and 17 of 20 Clostridium strains, respectively, but neither bound to other members of the cheese microbiota. However, GFP-EAD did not label any Clostridium strain tested. Unexpectedly, GFP-CTP1L and GFP-CBD were also able to bind to clostridial spores. In addition, GFP-CBD allowed us to visualize the vegetative cells of C. tyrobutyricum directly in the matrix of a LBD cheese. Site-directed mutants of GFP-CTP1L and GFP-CBD were made to examine the amino acids involved in binding and oligomer formation. Oligomerization was not essential for binding, but specific mutations in the CBD which affected oligomer formation also affected binding and lytic activity. We conclude that GFP-CTP1L and GFP-CBD could be good biomarkers for rapid detection of Clostridium spores in milk, so measures can be taken for the prevention of LBD in cheese, and also provide effective tools to study the development of Clostridium populations during cheese ripening.

Influence of reuterin-producing Lactobacillus reuteri coupled with glycerol on biochemical, physical and sensory properties of semi-hard ewe milk cheese

The biochemical, physical and sensory characteristics of ewe milk cheeses made with reuterin-producing Lactobacillus reuteri and glycerol (substrate for reuterin production) were assessed. Cheese made with lactococci starter (CTRL), cheese made with starter and L. reuteri (SLR), and cheese made with starter, L. reuteri and 30mM glycerol (SLR-G) were manufactured. L. reuteri reached counts above 7logcfu/g on day 1. Lactococci survival was enhanced in SLR cheese without affecting cheese pH, dry matter, proteolysis, concentration of most free amino acids (FAA), textural and most color parameters, or sensory characteristics. In situ production of reuterin by L. reuteri was only detected in SLR-G cheese, decreasing LAB counts although acidification remained unaffected. SLR-G cheese showed higher values of cell free aminopeptidase activity, overall proteolysis and FAA, particularly glutamic acid, than CTRL and SLR cheeses. The addition of L. reuteri-glycerol resulted in lower hardness and elasticity values in SLR-G cheese and influenced its L*, a* and b* color parameters. However, these changes, which were detected by instrumental analysis, did not affect the sensory scores for texture and color quality of SLR-G cheese, and it received the highest scores for taste quality. Our results suggest that L. reuteri-glycerol may provide a suitable system to release the antimicrobial reuterin in cheese without affecting negatively its sensory characteristics.

Application of high pressure processing for controlling Clostridium tyrobutyricum and late blowing defect on semi-hard cheese

In this study we evaluated the application of different high pressure (HP) treatments (200-500 MPa at 14 °C for 10 min) to industrial sized semi-hard cheeses on day 7, with the aim of controlling two Clostridium tyrobutyricum strains causing butyric acid fermentation and cheese late blowing defect (LBD). Clostridium metabolism and LBD appearance in cheeses were monitored by sensory (cheese swelling, cracks/splits, off-odours) and instrumental analyses (organic acids by HPLC and volatile compounds by SPME/GC-MS) after 60 days. Cheeses with clostridial spores HP-untreated and HP-treated at 200 MPa showed visible LBD symptoms, lower concentrations of lactic, citric and acetic acids, and higher levels of pyruvic, propionic and butyric acids and of 1-butanol, ethyl and methyl butanoate, and ethyl pentanoate than cheeses without spores. However, cheeses with clostridial spores and HP-treated at ≥ 300 MPa did not show LBD symptoms and their organic acids and volatile compounds profiles were comparable to those of their respective HP-treated control cheeses, despite HP treatments caused a low spore reduction. A decrease in C. tyrobutyricum spore counts was observed after curd pressing, which seems to indicate an early spore germination, suggesting that HP treatments ≥300 MPa were able to inactivate the emerged C. tyrobutyricum vegetative cells and, thereby, prevent LBD.

Effect of reuterin-producing Lactobacillus reuteri coupled with glycerol on the volatile fraction, odour and aroma of semi-hard ewe milk cheese

The effect of the biopreservation system formed by Lactobacillus reuteri INIA P572, a reuterin-producing strain, and glycerol (required for reuterin production), on the volatile fraction, aroma and odour of industrial sized semi-hard ewe milk cheese (Castellano type) was investigated over a 3-month ripening period. The volatile compounds were extracted and analyzed by SPME-GC-MS and cheese odour and aroma profiles were studied by descriptive sensory analysis. Control cheese was made only with a mesophilic starter and experimental cheeses with L. reuteri were made with and without glycerol. The addition of L. reuteri INIA P572 to milk enhanced the formation of six volatile compounds. Despite the changes in the volatile compounds profile, the use of L. reuteri INIA P572 did not noticeably affect the sensory characteristics of cheese. On the other hand, the addition of L. reuteri INIA P572 coupled with 30mM glycerol enhanced the formation of twelve volatile compounds, but decreased the formation of five ones. The use of the biopreservation system did not affect overall odour and aroma quality of cheese although it resulted in a significant decrease of the odour intensity scores. In addition, this cheese received significant higher scores for "cheesy" aroma and significant lower scores for the aroma attributes "milky", "caramel" and "yogurt-like". The first two axes of a principal component analysis (PCA) performed for selected volatile compounds and sensory characteristics, accounting for 75% of the variability between cheeses, separated cheeses made with L. reuteri INIA P572 and glycerol from the rest of cheeses, and also differentiated control cheese from cheeses made with L. reuteri INIA P572 from day 60 onward. Our results showed that the reuterin-producing L. reuteri INIA P572 strain, when coupled with glycerol, may be a suitable biopreservation system to use in cheese without affecting odour and aroma quality.

Physiological and biochemical characterization of the two α-l-rhamnosidases of Lactobacillus plantarum NCC245

This work is believed to be the first report on the physiological and biochemical characterization of α-l-rhamnosidases in lactic acid bacteria. A total of 216 strains representing 37 species and eight genera of food-grade bacteria were screened for α-l-rhamnosidase activity. The majority of positive bacteria (25 out of 35) were Lactobacillus plantarum strains, and activity of the L. plantarum strain NCC245 was examined in more detail. The analysis of α-l-rhamnosidase activity under different growth conditions revealed dual regulation of the enzyme activity, involving carbon catabolite repression and induction: the enzyme activity was downregulated by glucose and upregulated by l-rhamnose. The expression of the two α-l-rhamnosidase genes rhaB1 and rhaB2 and two predicted permease genes rhaP1 and rhaP2, identified in a probable operon rhaP2B2P1B1, was repressed by glucose and induced by l-rhamnose, showing regulation at the transcriptional level. The two α-l-rhamnosidase genes were overexpressed and purified from Escherichia coli. RhaB1 activity was maximal at 50 °C and at neutral pH and RhaB2 maximal activity was detected at 60 °C and at pH 5, with high residual activity at 70 °C. Both enzymes showed a preference for the α-1,6 linkage of l-rhamnose to β-d-glucose, hesperidin and rutin being their best substrates, but, surprisingly, no activity was detected towards the α-1,2 linkage in naringin under the tested conditions. In conclusion, we identified and characterized the strain L. plantarum NCC245 and its two α-l-rhamnosidase enzymes, which might be applied for improvement of bioavailability of health-beneficial polyphenols, such as hesperidin, in humans.

Disease of Floral Buds of Kiwifruit in Spain Caused by Pseudomonas syringae

In 1999 and 2000, decay of floral buds of Actinidia deliciosa was observed in plantations in the Principality of Asturias, Spain. Bud decay led to a decrease (up to 40%) in the production of kiwifruit. Floral buds with symptoms of browning and necrosis were collected from different areas (Villaviciosa, Grado, and Pravia) and processed for microbiological analysis. A fluorescent bacterium was recovered on King's B medium and identified as Pseudomonas syringae by the LOPAT scheme and Hugh-Leifson reaction (2). Other biochemical features included esculin and gelatin hydrolysis and acid production from mannitol, erythritol, sorbitol, and m-inositol, which are features associated with P. syringae (2). Three isolates from different samples were selected to test pathogenicity using Koch's postulates. Overnight broth cultures of each isolate (10⁹ CFU/ml) were used to infect A. deliciosa in the trials by the following procedures: (i) atomization on branches and buds; (ii) bud injection (1 ml in each bud); and (iii) bud cutting with a scalpel dipped in the suspension. Branches and buds inoculated with sterile water were used as controls. The inoculated parts were enclosed in plastic bags for 48 h. Assays were repeated at least twice. Disease symptoms appeared 2 days later, initially as dark brown spots that developed into an extensive bud rot in all inoculated cases, while no symptoms occurred in controls. P. syringae was successfully recovered from infected samples but not from control samples. The data support the pathogenicity of P. syringae on A. deliciosa. Although P. syringae was previously reported in Italy as the causal agent of disease on floral buds of A. deliciosa (1), to our knowledge, this is the first report of infection of kiwifruit by this pathogen in Spain. References: (1) G. M. Balestra and L. Varvaro. J. Phytopathol. 145:375, 1997. (2) MAPA, Manual de laboratorio, MAPA, Madrid, Spain, 1991.