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In the last few years, geomicrobiologists have focused their researches on the nature and origin of enigmatic reticulated filaments reported in modern and fossil samples from limestone caves and basalt lava tubes. Researchers have posed questions on these filaments concerning their nature, origin, chemistry, morphology, mode of formation and growth. A tentative microbial origin has been elusive since these filaments are found as hollow tubular sheaths and could not be affiliated to any known microorganism. We describe the presence of similar structures in a 16th century granite tunnel in Porto, Northwest Portugal. The reticulated filaments we identify exhibit fine geometry surface ornamentation formed by cross-linked Mn-rich nanofibres, surrounded by a large amount of extracellular polymeric substances. Within these Mn-rich filaments we report for the first time the occurrence of microbial cells. [ABSTRACT FROM AUTHOR]

Uranyl-evansites from Porto (Northwest Portugal) together with historical evansite standards from Galicia (Northwest Spain), Slovakia, and Congo were studied by Environmental Scanning Electron Microscopy (ESEM), Energy Dispersive Spectrometry (EDS), Back-Scattering (BS), Spectra Cathodoluminescence (CL), Micro-Raman and X-Ray Diffraction (XRD), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This work mainly focused on Porto's evansites collected from the urban underground, looking for uranyl groups and the subsequent air radon gas levels in hypogeal environments, for example, from 6000 to 7000 Bq/m3. Evansite (∼Al3(PO4)(OH)6 · 6H2O) comprises microlayers of amorphous hydrous aluminum-phosphate phases together with hydrolyzed uranyl groups and hydroxide UO2(OH)2 precipitates. The studied evansites contain uranyl groups reaching up to UO2 0.78% in the case of Kobokobo, as detected by EDS and CL, and 0.1% in the Porto samples, as detected by CL and ICP-MS. The CL spectra probe is a very fast tool in detecting uranyl groups. Raman spectra of evansites are homogeneous in samples from different localities and not previously published. Therefore, we suggest Zeleznik-type evansite as a new representative international Spectrum Raman pattern for evansite. [ABSTRACT FROM PUBLISHER]

A Gram-reaction-positive, motile, coccus-shaped actinobacterium, designated strain T2A-S27(T), was isolated from a roof tile in Oporto (Portugal) and studied using a polyphasic approach. The 16S rRNA gene sequence of the novel isolate showed high similarity to that of Kineococcus marinus KST3-3(T) (97.8 % sequence similarity). Strain T2A-S27(T) showed lower 16S rRNA gene sequence similarities with other members of the genus Kineococcus and members of the family Kineosporiaceae (<94 %). A phylogenetic tree, based on 16S rRNA gene sequences, showed that strain T2A-S27(T) formed a coherent clade with the type strain of K. marinus and Quadrisphaera granulorum. The isolate was characterized by the presence of meso-diaminopimelic acid in the cell-wall peptidoglycan, MK-9(H(2)) as the predominant menaquinone and a polar lipid profile consisting of diphosphatidylglycerol and phosphatidylglycerol. The fatty acid profile was dominated by anteiso-C(15 : 0). The DNA G+C content was 76.9 mol%. The low level of DNA-DNA relatedness to K. marinus (46-47 %) and the results of the chemotaxonomic and physiological studies clearly distinguished strain T2A-S27(T) from recognized species of the genus Kineococcus. On the basis of its phylogenetic position and phenotypic traits, strain T2A-S27(T) ( = LMG 24148(T)  = CECT 7306(T)  = DSM 23768(T)) represents a novel species of a new genus in the family Kineosporiaceae, for which the name Pseudokineococcus lusitanus gen. nov., sp. nov. is proposed. The misclassified species K. marinus is transferred to the new genus as Pseudokineococcus marinus comb. nov. The type strain of Pseudokineococcus marinus is KST3-3(T) ( = KCCM 42250(T)  = NRRL B-24439(T)).