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Thermal caves represent an environment characterized by unique chemical/physical properties, often used for treatment and care of musculoskeletal, respiratory, and skin diseases. However, these environments are poorly characterized for their physical and microbiological characteristics; furthermore, the recent pandemic caused by COVID-19 has highlighted the need to investigate the potential transmission scenario of SARS-CoV-2 virus in indoor environments where an in-depth analysis of the aerosol concentrations and dimensional distributions are essential to monitor the spread of the virus. This research work was carried out inside a natural cave located in Viterbo (Terme dei Papi, Italy) where a waterfall of sulfur–sulfate–bicarbonate–alkaline earth mineral thermal water creates a warm-humid environment with 100% humidity and 48 °C temperature. Characterization of the aerosol and bioaerosol was carried out to estimate the personal exposure to aerosol concentrations, as well as particle size distributions, and to give an indication of the native microbial load. The data obtained showed a predominance of particles with a diameter greater than 8 µm, associated with low ability of penetration in the human respiratory system. A low microbial load was also observed, with a prevalence of noncultivable strains generated by the aerosolization of the thermal waters. Finally, the estimation of SARS-CoV-2 infection risk by means of mathematical modeling revealed a low risk of transmission, with a decisive effect given by the mechanical ventilation system, which together with the adoption of social distancing measures makes the risk of infection extremely low. [ABSTRACT FROM AUTHOR]

Orange peel waste (OPW), the primary byproduct of the juice extraction process, is annually generated in massive amounts (21 Mton), and its aqueous extraction in biorefining operations yields a liquid fraction, referred to as orange peel extract (OPE). Although OPE contains significant amounts of easily assimilable carbohydrates, such as fructose, glucose, and sucrose, no investigations have been conducted yet to assess its possible use in biodiesel production by oleaginous yeasts. Consequently, the objective of the present study was to assess whether OPE might act as the basis of a liquid medium for microbial lipid production. A screening conducted with 18 strains of oleaginous yeasts in shaken flask on the OPE-based medium showed that Rhodosporidium toruloides NRRL 1091 and Cryptococcus laurentii UCD 68-201 gave the best results in terms of lipid production (5.8 and 4.5 g L−1, respectively) and accumulation (77 and 47% on a dry matter basis, respectively). The subsequent scale transfer of the process to a 3-L STR operated in batch mode halved the time required to reach the lipid peak with the ensuing increase in volumetric productivities in R. toruloides NRRL 1091 (3646 mg L−1 day−1) and C. laurentii UCD 68-201 (2970.7 mg L−1 day−1). The biodiesel yields from the lipids of the former and the latter strain were 36.9 and 31.9%, respectively. Based on multivariate analysis of fatty acid methyl ester compositions, the lipids from the former and the latter strain were highly resembling those of Jatropha and palm oils, two commonly used feedstocks for biodiesel manufacturing. [ABSTRACT FROM AUTHOR]

Orange peel waste was converted into ethanol by consecutive acid-catalyzed steam-explosion (ACSE), enzymatic saccharification, and fermentation with Saccharomyces cerevisiae F15. With the aim of increasing the concentration of fermentable sugars in the hydrolysate and to fully recycle the spent acid liquor as the suspending medium for saccharification, the technical feasibility of increasing the solid loading in the ACSE step from 160 to 480 g L was assessed. At high solid loading in the ACSE pretreatment (HSLAP), the solubilization degrees of polysaccharides were lower while those of potential inhibitors (e.g., acetic and formic acids and phenols) were generally higher than those found at low solid loading (LSLAP). However, residual solids from both solid loadings showed similar susceptibility to enzymatic saccharification (ES) in a 7-L stirred-tank reactor (STR) (cellulase, 12 FPU g cellulose; pectinase, 25 IU g dry matter; 72 h incubation at 50 °C). Fermentation was performed in a 1-L STR along five repeated batches with the first one being used to enable yeast proliferation. By using the hydrolysates arising from the HSLAP-ES combination, it was possible to rely on a fermentation medium with a 2.5-fold higher concentration of simple sugars and to double the ethanol concentration in the final beer to be distilled of. However, the higher content of inhibitory compounds in hydrolysates from HSLAP-ES than in the LSLAP-ES ones led to a reduction in the ethanol yield per unit substrate consumed (0.49 vs. 0.41 g g, respectively) and overall productivity (3.4 vs. 2.7 g h, respectively). [ABSTRACT FROM AUTHOR]

Fungal strains naturally occurring on the wood and leaves of the salt-excreting desert tree Tamarix were isolated and characterized for their ability to produce cellulose- and starch-degrading enzymes. Of the 100 isolates, six fungal species were identified by ITS1 sequence analysis. No significant differences were observed among taxa isolated from wood samples of different Tamarix species, while highly salt-tolerant forms related to the genus Scopulariopsis (an anamorphic ascomycete) occurred only on the phylloplane of T. aphylla. All strains had cellulase and amylase activities, but the production of these enzymes was highest in strain D, a Schizophyllum-commune-related form. This strain, when grown on pretreated Tamarix biomass, produced an enzymatic complex containing levels of filter paperase (414 ± 16 IU/ml) that were higher than those of other S. commune strains. The enzyme complex was used to hydrolyze different lignocellulosic substrates, resulting in a saccha-rification rate of pretreated milk thistle (73.5 ± 1.2 %) that was only 10 % lower than that obtained with commercial cellulases. Our results support the use of Tamarix biomass as a useful source of cellulolytic and amylolytic fungi and as a good feedstock for the economical production of commercially relevant cellulases and amylases. [ABSTRACT FROM AUTHOR]

A novel bacterium, strain BM90, previously isolated from Tyrrhenian Sea, was metabolically characterized testing its ability to use 95 different carbon sources by the Biolog system. The bacterium showed a broad capacity to use fatty-, organic- and amino-acids; on the contrary, its ability to use carbohydrates was extremely scarce. Strain BM90 was identified and affiliated to Delftia tsuruhatensis by molecular techniques based on 16S rRNA gene sequencing. D. tsuruhatensis BM90, cultivated in shaken cultures, was able to grow on various phenolic compounds and to remove them from its cultural broth. The phenols used, chosen for their presence in industrial or agro-industrial effluents, were grouped on the base of their chemical characteristics. These included benzoic acid derivatives, cinnamic acid derivatives, phenolic aldehyde derivatives, acetic acid derivatives and other phenolic compounds such as catechol and p-hydroxyphenylpropionic acid. When all the compounds (24) were gathered in the same medium (total concentration: 500 mg/l), BM90 caused the complete depletion of 18 phenols and the partial removal of two others. Only four phenolic compounds were not removed. Flow cytometry studies were carried out to understand the physiological state of BM90 cells in presence of the above phenols in various conditions. At the concentrations tested, a certain toxic effect was exerted only by the four compounds that were not metabolized by the bacterium. [ABSTRACT FROM AUTHOR]