Current and future chemical treatments to fight biodeterioration of outdoor building materials and associated biofilms: Moving away from ecotoxic and towards efficient, sustainable solutions

Filamentous fungi play a key role in the terrestrial carbon cycle as they are the primary decomposers of lignocellulose in soil organic matter (SOM). Fungi secrete a wide range of oxidative and hydrolytic enzymes, and generate radicals through extracellular secondary metabolites to decompose SOM. To study fungal decomposition of SOM, the activities of isolated enzymes are typically studied as proxies for the decomposition activity of fungi. However, extracellular enzymes involved in lignocellulose decomposition are often bound to fungal extracellular polymeric substance (EPS) matrices. This association between extracellular enzymes and EPS matrices affects the activities of the enzymes. Moreover, extracellular enzymes and fungal cells are prone to attack by radicals and proteolytic enzymes themselves. Hence, these seemingly incompatible decomposition mechanisms must be regulated in some way in the fungal extracellular space to allow efficient decomposition of SOM, while preventing damage to secreted extracellular enzymes or the fungal cells themselves. We here review studies investigating the associations between fungal extracellular enzymes and EPS matrices and how these associations affect hydrolytic and oxidative reactions involved in SOM decomposition. Based on the knowledge compiled in the current review, we propose that fungal EPS matrices should be viewed as highly dynamic and functional parts of the fungal extracellular decomposition machinery. We also build a conceptual illustration that describes how the molecular composition and structure of fungal EPS matrices ensure that extracellular decomposition reactions only proceed at the right time and in the right place.

Fungal extracellular polymeric substance matrices – Highly specialized microenvironments that allow fungi to control soil organic matter decomposition reactions

Fungal Infections Diagnosis – Past, Present and Future

Lactobacilli are among the most studied bacteria in the microbiome of the orodigestive and genitourinary tracts. As probiotics, lactobacilli may provide various benefits to the host. These benefits include regulating the composition of the resident microbiota, preventing –or even potentially reverting- a dysbiotic state. Candida albicans is an opportunistic pathogen that can influence and be influenced by other members of the mucosal microbiota and, under immune-compromising conditions, can cause disease. Lactobacillus and Candida species can colonize the same mucosal sites; however, certain Lactobacillus species display antifungal activities that can contribute to low Candida burdens and prevent fungal infection. Lactobacilli can produce metabolites with direct anticandidal function or enhance the host defense mechanisms against fungi. Most of the Lactobacillus spp anticandidal mechanisms of action remain underexplored. This work aims to comprehensively review and provide an update on the current knowledge regarding these anticandidal mechanisms.

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Anticandidal Activities by Lactobacillus Species: An Update on Mechanisms of Action

Background The second wave of COVID-19 pandemic has seen an unprecedented rise in the number of mucormycosis cases worldwide and in India particularly. This otherwise rare fungal infection has become an endemic among patients who have recovered from recent SARS-CoV-2 infection. Among the different types of mucormycosis, rhino-orbital-cerebral involvement has mainly been observed in the recent surge of cases. Very few cases of mucormycosis of mandible have been reported in literature and none in COVID-19 patients. We report a case of isolated mandibular mucormycosis in a COVID- 19 patient, with no other predisposing comorbidities. Case report. A 39 year old patient recently recovered from COVID-19 presented with typical symptoms of osteomyelitis which was confirmed using computed tomography of face. He underwent thorough debridement and curettage and tissue was sent for culture, special staining and biopsy. Result Diagnosis of mucormycosis was confirmed based on postoperative biopsy and special staining. He was further managed with complete course of appropriate antifungal therapy. Conclusion Mucormycosis is a fulminant and aggressive infection which requires prompt diagnosis and intervention. Early referral to a maxillofacial surgeon by physicians and general dental practitioners on seeing signs and symptoms of secondary fungal infections involving maxilla or mandible in patients with history of SARS-CoV-19 infection can improve prognosis.

Mandibular mucormycosis following SARS-CoV-2 infection - A case report and review of literature.

Mangrove sediments from New Caledonia were screened for xylanase sequences. One enzyme was selected and characterized both biochemically and for its industrial potential. Using a specific cDNA amplification method coupled with a MiSeq sequencing approach, the diversity of expressed genes encoding GH11 xylanases was investigated beneath Avicenia marina and Rhizophora stylosa trees during the wet and dry seasons and at two different sediment depths. GH11 xylanase diversity varied more according to tree species and season, than with respect to depth. One complete cDNA was selected (OFU29) and expressed in Pichia pastoris. The corresponding enzyme (called Xyn11-29) was biochemically characterized, revealing an optimal activity at 40–50 °C and at a pH of 5.5. Xyn11-29 was stable for 48 h at 35 °C, with a half-life of 1 h at 40 °C and in the pH range of 5.5–6. Xyn11-29 exhibited a high hydrolysis capacity on destarched wheat bran, with 40% and 16% of xylose and arabinose released after 24 h hydrolysis. Its activity on wheat straw was lower, with a release of 2.8% and 6.9% of xylose and arabinose, respectively. As the protein was isolated from mangrove sediments, the effect of sea salt on its activity was studied and discussed.

https://hal-insu.archives-ouvertes.fr/insu-03293424/document

Corinne Ivaldi

Papers

Screening New Xylanase Biocatalysts from the Mangrove Soil Diversity