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Microbial diversity in lava tubes from Canary Islands (Spain) has never been explored thus far offering a unique opportunity to study subsurface microbiology. Abundant yellow coloured mats developing on coralloid speleothems in a lava tube from La Palma Islands were studied by next-generation sequencing and DNA/RNA clone library analyses for investigating both total and metabolically active bacteria. In addition, morphological and mineralogical characterization was performed by field emission scanning electron microscopy (FESEM), micro-computed tomography, X-ray diffraction and infrared spectroscopy to contextualize sequence data. This approach showed that the coralloid speleothems consist of banded siliceous stalactites composed of opal-A and hydrated halloysite. Analytical pyrolysis was also conducted to infer the possible origin of cave wall pigmentation, revealing that lignin degradation compounds can contribute to speleothem colour. Our RNA-based study showed for the first time that members of the phylum Actinobacteria, with 55% of the clones belonging to Euzebyales order, were metabolically active components of yellow mats. In contrast, the DNA clone library revealed that around 45% of clones were affiliated to Proteobacteria. Composition of microbial phyla obtained by NGS reinforced the DNA clone library data at the phylum level, in which Proteobacteria was the most abundant phylum followed by Actinobacteria.

L-asparaginase is an important enzyme as therapeutic agents used in combination with other drugs in the treatment of acute lymphoblastic leukemia. A newly isolated actinomycetes strain, Streptomyces sp. NEAE-82, was potentially producing extracellular L-asparaginase, it was identified as Streptomyces fradiae NEAE-82, sequencing product was deposited in the GenBank database under accession number KJ467538. L-asparaginase was purified from the crude enzyme using ammonium sulfate precipitation, dialysis and ion exchange chromatography using DEAE Sepharose CL-6B. Further the kinetic studies of purified enzyme were carried out. The optimum pH, temperature and incubation time for maximum L-asparaginase activity were found to be 8.5, 40 °C and 30 min, respectively. The optimum substrate concentration was found to be 0.06 M. The Km and Vmax of the enzyme were 0.01007 M and 95.08 Uml(-1)min(-1), respectively. The half-life time (T1/2) was 184.91 min at 50 °С, while being 179.53 min at 60 °С. The molecular weight of the subunits of L-asparaginase was found to be approximately 53 kDa by SDS-PAGE analysis. The purified L-asparaginase showed a final specific activity of 30.636 U/mg protein and was purified 3.338-fold. The present work for the first time reported more information in the production, purification and characterization of L-asparaginase produced by newly isolated actinomycetes Streptomyces fradiae NEAE-82.

A new trehalose analog, lentztrehalose [4-O-(2,3-dihydroxy-3-methylbutyl)trehalose], was isolated from an actinomycete Lentzea sp. Lentztrehalose is only weakly hydrolyzed by the trehalose-hydrolyzing enzyme, trehalase, so can be regarded as an enzyme-stable analog of trehalose. Although lentztrehalose does not show apparent toxicity to mammalian cells and microbes, it has antitumor activity in mice bearing S-180 sarcoma and Ehrlich carcinoma cells. In ovariectomized mice, lentztrehalose displayed a bone reinforcement effect in the femur that was superior to trehalose and induced non-morbid suppression of weight gain comparable with trehalose. These results indicate that enzyme-stable analogs of trehalose, such as lentztrehalose, may be more beneficial for human health and thus have potential as substitutes for trehalose as a sweetener.

A novel Gram-stain-positive actinobacterium, designated RI148-Li105(T), was isolated from a lichen sample from Rishiri Island, Japan, and its taxonomic position was investigated by a polyphasic approach. 16S rRNA gene sequencing study indicated that strain RI148-Li105(T) was related to the type strain of Luteimicrobium subarcticum, with a similarity of 97.8%. Cells of strain RI148-Li105(T) exhibited a rod-coccus cycle. The diagnostic cell-wall diamino acid of this organism was lysine and the peptidoglycan type was found to be A4α. The predominant menaquinones were MK-8(H(2)) and MK-9(H(2)), and the major fatty acids were iso-C(16:0), C(17:1) ω9c and C(17:0). The DNA G+C content was 73.6 mol%. The major phenotypic characteristics of strain RI148-Li105(T) basically corresponded to those of the genus Luteimicrobium excluding the fatty acid composition. These results suggest that strain RI148-Li105(T) should be affiliated with the genus Luteimicrobium. Meanwhile, DNA-DNA hybridization and some phenotypic characteristics revealed that the strain differs from L. subarcticum. Therefore, strain RI148-Li105(T) represents a novel species of the genus Luteimicrobium, for which the name Luteimicrobium album sp. nov. is proposed. The type strain of Luteimicrobium album is RI148-Li105(T) (=NBRC 106348(T)=DSM 24866(T)).

In the screening of antitumor compounds from microbial secondary metabolites, myxochelin A was isolated from a culture broth of Nonomuraea pusilla TP-A0861. The absolute configuration was determined to be S by synthesizing both enantiomers from an L- or D-lysine derivative and comparing their specific rotations. Both enantiomers of myxochelin A showed remarkable inhibitory effects on the invasion of murine colon 26-L5 carcinoma cells at non-cytotoxic concentrations.