Actinoplanes luteus sp. nov., isolated from soil.

A novel filamentous bacterial strain, A-T 5190T, which developed irregular sporangia at the end of sporangiophores on substrate mycelia, was isolated from dry evergreen forest soil collected in Thailand. The 16S rRNA gene sequence and phylogenetic analysis indicated that strain A-T 5190T belonged to the genus Actinoplanes and was related most closely to Actinoplanes palleronii NBRC 14916T (98.88 % similarity) and Actinoplanes rectilineatus NBRC 13941T (98.54 %). DNA-DNA relatedness values between strain A-T 5190T and its closest relatives were below 70 %. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained rhamnose, ribose, galactose and xylose. The predominant menaquinone was MK-9(H4). The diagnostic phospholipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. The predominant cellular fatty acids were unsaturated fatty acid C17 : 1 and branched fatty acids iso-C16 : 0, iso-C15 : 0 and anteiso-C17 : 0. The G+C content of the genomic DNA was 71.9 mol%. Evidence from phenotypic, chemotaxonomic and genotypic studies indicate that strain A-T 5190T represents a novel species of the genus Actinoplanes, for which the name Actinoplanes luteus sp. nov. is proposed. The type strain is A-T 5190T ( = BCC 41582T = NBRC 109644T).

Sinosporangium fuscum sp. nov., isolated from soil.

A novel actinomycete, A-T 8343T was isolated from a moist evergreen forest soil sample collected in the Trat Province, Thailand. Based on 16S rRNA gene sequence analysis, strain A-T 8343T belonged to the genus Sinosporangium and was closely related to Sinosporangium siamense A-T 1946T (98.81 %) and Sinosporangium album 6014T (98.54 %). The DNA-DNA relatedness values were 21.8-27 % with S. siamense A-T 1946T and 31.1-31.9 % with S. album 6014T, which were significantly below 70 %. The result differentiated A-T 8343T from the closest species. The organism developed spherical sporangia containing non-motile spores on aerial mycelia. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained rhamnose, ribose, madurose and glucose. The predominant menaquinones were MK-9(H2) and MK-9(H4). The diagnostic phospholipids were phosphatidylmethylethanolamine, phosphatidylethanolamine, hydroxyl-phosphatidylethanolamine, diphosphatidylglycerol, lyso-phosphatidylethanolamine, N-acetylglucosamine-containing phospholipids, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol-mannosides, aminophosphoglycolipid and one unknown phospholipid. The major cellular fatty acids were saturated C16 : 0, iso C16 : 0, unsaturated C16 : 1 and C18 : 1. Following an evaluation of phenotypic, chemotaxonomic and genotypic characteristics, the new isolate is proposed as a representative novel species of the genus Sinosporangium to be named Sinosporangiumfuscum sp. nov. The type strain is A-T 8343T ( = BCC 52770T = NBRC 109516T).

Luteipulveratus halotolerans sp. nov., an actinobacterium (Dermacoccaceae) from forest soil.

The taxonomic position of an actinobacterium strain, C296001T, isolated from a soil sample collected in Sarawak, Malaysia, was established using a polyphasic approach. Phylogenetically, strain C296001T was closely associated with the genus Luteipulveratus and formed a distinct monophyletic clade with the only described species, Luteipulveratus mongoliensis NBRC 105296T. The 16S rRNA gene sequence similarity between strain C296001T and L. mongoliensis was 98.7 %. DNA-DNA hybridization results showed that the relatedness of strain C296001T to L. mongoliensis was only 21.5 %. The DNA G+C content of strain C296001T was 71.7 mol%. Using a PacBio RS II system, whole genome sequences for strains C296001T and NBRC 105296T were obtained. The genome sizes of 4.5 Mbp and 5.4 Mbp determined were similar to those of other members of the family Dermacoccaceae. The cell-wall peptidoglycan contained lysine, alanine, aspartic acid, glutamic acid and serine, representing the peptidoglycan type A4α l-Lys-l-Ser-d-Asp. The major menaquinones were MK-8(H4), MK-8 and MK-8(H2). Phosphatidylglycerol, phosphatidylinositol, diphosphatidylglycerol and phosphoglycolipid were the polar lipids, while the whole-cell sugars were glucose, fucose and lesser amounts of ribose and galactose. The major fatty acids were iso-C16 : 0, anteiso-C17 : 0, iso-C16 : 1 H, anteiso-C17 : 1ω9c, iso-C18 : 0 and 10-methyl C17 : 0. Chemotaxonomic analyses showed that C296001T had typical characteristics of members of the genus Luteipulveratus, with the main differences occurring in phenotypic characteristics. On the basis of the phenotypic and chemotaxonomic evidence, it is proposed that strain C296001T be classified as a representative of a novel species in the genus Luteipulveratus, for which the name Luteipulveratus halotolerans sp. nov. is recommended. The type strain is C296001T ( = ATCC TSD-4T = JCM 30660T).

Planobispora takensis sp. nov., isolated from soil.

A novel Gram-stain-positive, filamentous bacterial strain (A-T 7458(T)) was isolated from soil collected from hill evergreen forest in Thailand. The strain developed cylindrical sporangia containing a longitudinal pair of motile spores, on short ramifications of aerial mycelia. From a taxonomic study using a polyphasic approach, strain A-T 7458(T) had typical characteristics of members of the genus Planobispora. 16S rRNA gene sequence analysis indicated that the isolate was closely related to Planobispora siamensis A-T 4600(T) (98.5 %), Planobispora rosea JCM 3166(T) (97.6 %) and Planobispora longispora NBRC 13918(T) (97.6 %). The DNA-DNA relatedness values, which differentiated the novel strain from the closest species, were significantly below 70 %. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, madurose, mannose and glucose. The predominant menaquinone was MK-9(H2). The diagnostic phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylinositol, phosphatidylinositol-mannoside and aminophosphoglycolipid. The predominant cellular fatty acids were unsaturated C17 : 1 and C18 : 1, and saturated C16 : 0 and C17 : 0. Following an evaluation of phenotypic, chemotaxonomic and genotypic characteristics, the novel isolate is proposed to represent a novel species of the genus Planobispora, to be named Planobispora takensis sp. nov. The type strain is A-T 7458(T) ( = BCC 48396(T) = NBRC 109077(T)).

Sinosporangium siamense sp. nov., isolated from soil and emended description of the genus Sinosporangium.

An actinomycetes strain A-T 1946(T) that developed spherical sporangia containing non-motile spores on aerial mycelia was isolated from dry deciduous forest soil in Thailand. 16S rRNA gene sequence analysis indicated that strain A-T 1946(T) belongs to the genus Sinosporangium, being closely related to Sinosporangium album 6014(T) (98.8% sequence similarity). The DNA-DNA relatedness values were 43.7-50.9%, which were significantly below 70% and differentiated strain A-T 1946(T) from the closest species. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained rhamnose, ribose, madurose and glucose. The predominant menaquinone was MK-9(H2). The diagnostic phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, lysophosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol-mannoside, N-acetylglucosamine-containing phospholipids, two unknown phosphoglycolipids and two unknown phospholipids. The predominant cellular fatty acids were unsaturated C(16 : 1) and C(17 : 1), and saturated C(16 : 0) and 10-methyl-C(17 : 0). Following an evaluation of phenotypic, chemotaxonomic and genotypic characteristics, the isolate is proposed to represent a novel species of genus Sinosporangium to be named Sinosporangium siamense sp. nov. The type strain is A-T 1946(T) ( = BCC 29081(T) = NBRC 109515(T)). An emended description of the genus Sinosporangium is also provided.

Actinoplanes siamensis sp. nov., isolated from soil.

A Gram-positive filamentous bacterial strain that developed large campanulate sporangia at the ends of sporangiophores on substrate mycelium was isolated from bamboo forest soil in Thailand. According to the results of a polyphasic taxonomic study, our isolate had typical characteristics of members of the genus Actinoplanes. The 16S rRNA gene sequence analysis also indicated that strain A-T 6646(T) belonged to the genus Actinoplanes, being most closely related to Actinoplanes liguriensis DSM 43865(T) (97.61 %) and Actinoplanes octamycinicus NBRC 14524(T) (97.52 %). The DNA-DNA relatedness values, which differentiate the new strain from the most closely related species, were significantly below 70 %. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained xylose and arabinose. The predominant menaquinone was MK-9(H4). The diagnostic phospholipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. The predominant cellular fatty acids were iso-C16 : 0, anteiso-C17 : 0, iso-C15 : 0 and anteiso-C15 : 0. Following an evaluation of phenotypic, chemotaxonomic and genotypic studies, the isolate is proposed to represent a novel species to be named Actinoplanes siamensis sp. nov. The type strain is A-T 6646(T) (= BCC 46194(T) = NBRC 109076(T)).

Kutzneria buriramensis sp. nov., isolated from soil, and emended description of the genus Kutzneria.

A Gram-staining-positive, filamentous bacterium, which developed large globose sporangia at the ends of long sporangiophores on aerial mycelium, was isolated from dry soil collected in a deciduous forest in Thailand. The cell-wall peptidoglycan of the novel bacterium, which was designated strain A-T 1846(T), contained meso-diaminopimelic acid and the whole-cell sugars comprised rhamnose, ribose, mannose, glucose and galactose. The predominant menaquinone was MK-9(H(4)). Mycolic acids were not detected. The identified phospholipids were phosphatidylmethylethanolamine, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylinositol, phosphatidylglycerol and diphosphatidylglycerol. The predominant cellular fatty acids were iso-C(16:0), iso-C(16 : 0) 2-OH and C(16 : 0) 10-methyl. The G+C content of the genomic DNA was 72 mol%. The phenotypic and chemotaxonomic characteristics of the novel strain resembled those of established members of the genus Kutzneria. Phylogenetic analyses based on 16S rRNA gene sequences also indicated that this strain belonged to the genus Kutzneria but as a representative of a putative novel species. In hybridization experiments, the DNA-DNA relatedness values recorded between the novel strain and established members of the genus Kutzneria all fell well below 70 %. Based on the phenotypic, chemotaxonomic and genotypic evidence and the results of the DNA-DNA hybridizations, strain A-T 1846(T) represents a novel species in the genus Kutzneria, for which the name Kutzneria buriramensis sp. nov. is proposed. The type strain is A-T 1846(T) (=BCC 29373(T) =NBRC 107931(T)). An emended description of the genus Kutzneria is provided.

Planobispora siamensis sp. nov., isolated from soil.

A novel actinomycete strain, A-T 4600(T), which developed cylindrical sporangia containing a longitudinal pair of motile spores forming singly or in bundles on short ramifications of the aerial mycelium, was isolated from soil collected from an evergreen forest in Thailand. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, madurose, mannose and glucose. The predominant menaquinones were MK-9(H2). Mycolic acids were not detected. The diagnostic phospholipids were phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylinositol, phosphatidylglycerol, phosphatidylinositol mannoside, diphosphatidylglycerol and aminophosphoglycolipid. The predominant cellular fatty acids were unsaturated C17 : 1, C18 : 1, saturated C16 : 0, and C17 : 0. The G+C content of the DNA was 70.8 mol%. Phenotypic and chemotaxonomic analyses showed that the isolate had the typical characteristics of members of the genus Planobispora. Furthermore, 16S rRNA gene sequence analysis also indicated that this strain belonged to the genus Planobispora but as a putative novel species. DNA-DNA relatedness values that differentiate the isolate from previously described members of the genus Planobispora were significantly below 70 %. Following an evaluation of phenotypic, chemotaxonomic and genotypic studies, it is proposed that the isolate represents a novel species, Planobispora siamensis sp. nov.; the type strain is A-T 4600(T) ( = BCC 39469(T) = NBRC 107568(T)).

Library-based discovery and characterization of daphnane diterpenes as potent and selective HIV inhibitors in Daphne gnidium.

Despite the existence of an extended armamentarium of effective synthetic drugs to treat HIV, there is a continuing need for new potent and affordable drugs. Given the successful history of natural product based drug discovery, a library of close to one thousand plant and fungal extracts was screened for antiretroviral activity. A dichloromethane extract of the aerial parts of Daphne gnidium exhibited strong antiretroviral activity and absence of cytotoxicity. With the aid of HPLC-based activity profiling, the antiviral activity could be tracked to four daphnane derivatives, namely, daphnetoxin (1), gnidicin (2), gniditrin (3), and excoecariatoxin (4). Detailed anti-HIV profiling revealed that the pure compounds were active against multidrug-resistant viruses irrespective of their cellular tropism. Mode of action studies that narrowed the site of activity to viral entry events suggested a direct interference with the expression of the two main HIV co-receptors, CCR5 and CXCR4, at the cell surface by daphnetoxin (1).

Sphaerisporangium krabiense sp. nov., isolated from soil.

A Gram-staining-positive, filamentous bacterial strain, designated A-T 0308(T), was isolated from soil of a tropical mangrove forest in Thailand. Strain A-T 0308(T) developed spherical sporangia containing non-motile spores on aerial mycelium. The novel strain contained meso-diaminopimelic acid, N-acetyl-type peptidoglycan and madurose, mannose, ribose, galactose and glucose as whole-cell sugars. The predominant menaquinones were MK-9(H(4)) and MK-9(H(6)); a small amount of MK-9(H(2)) and MK-9 was also detected. Mycolic acids were not detected. The diagnostic phospholipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and phosphoglycolipid. The predominant cellular fatty acids were iso-C(16:0) and 10-methylated C(17:0). The G+C content of the DNA was 72 mol%. Phenotypic and chemotaxonomic analyses showed that the novel isolate had characteristics typical of members of the genus Sphaerisporangium. 16S rRNA gene sequence analysis also indicated that the strain belongs to the genus Sphaerisporangium and that it represents a clade distinct from other members of the genus with sequence similarities ranging from 96.3 to 97.8% between the novel strain and its closest relatives. Based on the results of phenotypic, chemotaxonomic and phylogenetic studies, strain A-T 0308(T) (=BCC 21702(T) =NBRC 107571(T)) represents a novel species of the genus Sphaerisporangium, for which the name Sphaerisporangium krabiense sp. nov. is proposed.

Erratum: Basik et al. Microbial Degradation of Rubber: Actinobacteria. Polymers 2021, 13, 1989.

The authors wish to make the following changes to the published paper [...].

Microbial Degradation of Rubber: Actinobacteria.

Rubber is an essential part of our daily lives with thousands of rubber-based products being made and used. Natural rubber undergoes chemical processes and structural modifications, while synthetic rubber, mainly synthetized from petroleum by-products are difficult to degrade safely and sustainably. The most prominent group of biological rubber degraders are Actinobacteria. Rubber degrading Actinobacteria contain rubber degrading genes or rubber oxygenase known as latex clearing protein (lcp). Rubber is a polymer consisting of isoprene, each containing one double bond. The degradation of rubber first takes place when lcp enzyme cleaves the isoprene double bond, breaking them down into the sole carbon and energy source to be utilized by the bacteria. Actinobacteria grow in diverse environments, and lcp gene containing strains have been detected from various sources including soil, water, human, animal, and plant samples. This review entails the occurrence, physiology, biochemistry, and molecular characteristics of Actinobacteria with respect to its rubber degrading ability, and discusses possible technological applications based on the activity of Actinobacteria for treating rubber waste in a more environmentally responsible manner.

Exobiopolymer production of Ophiocordyceps dipterigena BCC 2073: optimization, production in bioreactor and characterization.

BACKGROUND: Biopolymers have various applications in medicine, food and petroleum industries. The ascomycetous fungus Ophiocordyceps dipterigena BCC 2073 produces an exobiopolymer, a (1-->3)-beta-D-glucan, in low quantity under screening conditions. Optimization of O. dipterigena BCC 2073 exobiopolymer production using experimental designs, a scale-up in 5 liter bioreactor, analysis of molecular weight at different cultivation times, and levels of induction of interleukin-8 synthesis are described in this study. RESULTS: In order to improve and certify the productivity of this strain, a sequential approach of 4 steps was followed. The first step was the qualitative selection of the most appropriate carbon and nitrogen sources (general factorial design) and the second step was quantitative optimization of 5 physiological factors (fractional factorial design). The best carbon and nitrogen source was glucose and malt extract respectively. From an initial production of 2.53 g x L(-1), over 13 g x L(-1) could be obtained in flasks under the improved conditions (5-fold increase). The third step was cultivation in a 5 L bioreactor, which produced a specific growth rate, biomass yield, exobiopolymer yield and exobiopolymer production rate of 0.014 h-1, 0.32 g x g(-1) glucose, 2.95 g x g biomass(-1) (1.31 g x g(-1) sugar), and 0.65 g x (L x d)(-1), respectively. A maximum yield of 41.2 g x L(-1) was obtained after 377 h, a dramatic improvement in comparison to the initial production. In the last step, the basic characteristics of the biopolymer were determined. The molecular weight of the polymer was in the range of 6.3 x 10(5) - 7.7 x 10(5) Da. The exobiopolymer, at 50 and 100. microg x mL(-1), induced synthesis in normal dermal human fibroblasts of 2227 and 3363 pg x mL(-1) interleukin-8 respectively. CONCLUSIONS: High exobiopolymer yield produced by O. dipterigena BCC 2073 after optimization by qualitative and quantitative methods is attractive for various applications. It induced high IL-8 production by normal dermal fibroblasts, which makes it promising for application as wound healing material. However, there are still other possible applications for this biopolymer, such as an alternative source of biopolymer substitute for hyaluronic acid, which is costly, as a thickening agent in the cosmetic industry due to its high viscosity property, as a moisturizer, and in encapsulation.

Planotetraspora kaengkrachanensis sp. nov. and Planotetraspora phitsanulokensis sp. nov., isolated from soil.

Two novel bacterial strains were isolated from tropical rain forest soil from Thailand. Strains A-T 0875(T) and A-T 1383(T) stained Gram-positive and were filamentous bacteria that developed cylindrical sporangia containing four oval- to rod-shaped spores at the ends of short sporangiophores on branched aerial mycelium. The cell-wall peptidoglycan contained meso-diaminopimelic acid, glutamic acid and alanine as cell-wall amino acids; whole-cell hydrolysates contained rhamnose, madurose, glucose, galactose and 3-O-methylmannose as whole-cell sugars. The predominant menaquinone was MK-9(H(4)). Mycolic acids were not detected. The diagnostic phospholipid was phosphatidylethanolamine. The predominant cellular fatty acids were iso-C(16 : 0) and 10-methyl-C(17 : 0). For both strains, the G+C content of the genomic DNA was 71 mol%. Phenotypic and chemotaxonomic analyses showed that the characteristics of the two isolates were typical of members of the genus Planotetraspora. Furthermore, 16S rRNA gene sequence analysis also indicated that the strains belonged to the genus Planotetraspora but as representatives of two novel species. Following an evaluation of our phenotypic, chemotaxonomic and genotypic studies, two novel species are proposed, Planotetraspora kaengkrachanensis sp. nov. (type strain A-T 0875(T)=BCC 24832(T)=NBRC 104272(T)) and Planotetraspora phitsanulokensis sp. nov. (type strain A-T 1383(T)=BCC 26045(T)=NBRC 104273(T)).

Planotetraspora thailandica sp. nov., isolated from soil in Thailand.

A Gram-positive-staining, filamentous bacterial strain that developed cylindrical sporangia containing four oval- to rod-shaped spores at the ends of short sporangiophores on branched aerial mycelium was isolated from tropical rainforest soil near a hot spring. The cell-wall peptidoglycan contained meso-diaminopimelic acid, glutamic acid and alanine as cell-wall amino acids; the whole-cell hydrolysate contained rhamnose, madurose, glucose, galactose and 3-O-methylmannose as whole-cell sugars. The predominant menaquinone was MK-9(H(4)). Mycolic acids were not detected. The diagnostic phospholipid was phosphatidylethanolamine. The predominant cellular fatty acids were iso-C(16 : 0) and 10-methylated C(17 : 0). The G+C content of the DNA was 71.1 mol%. The phenotypic and chemotaxonomic analyses showed that the isolate had characteristics typical of members of the genus Planotetraspora. Furthermore, 16S rRNA gene sequence analysis also indicated that this strain belongs to the genus Planotetraspora, but as a putative novel species. Following phenotypic, chemotaxonomic and genotypic studies, the isolate is proposed to be a representative of a novel species, to be named Planotetraspora thailandica sp. nov. The type strain is BCC 21825(T) (=NBRC 104271(T)). An emended description of the genus Planotetraspora is also presented.