Parasites with zoonotic potential found in commercially important fish in Tamaulipas,Northeastern Mexico

Human population is exposed to numerous parasitic ichthyozoonoses. Although Tamaulipas state (northeastern Mexico) is well known for its fishing and aquaculture industry, there are few reports of this type of zoonosis. Therefore, it is imperative to investigate whether the parasites that affect these fish may represent a zoonotic risk for the inhabitants of the area.The objective of this study was to identify molecular and/or morphologically muscle parasites of fish from coastal locations in Tamaulipas, Mexico, and assess the risk of infection for humans. Between 2017 and 2018, 764 individual fish belonging to 28 species were examined for parasites. Collected worms were processed for their identification using morphological characteristics. In addition, partial sequences of the large subunit (28S) ribosomal RNA gene were obtained from some species to corroborate their identity. Prevalence and mean intensity of all registered infections were calculated. A total of seven species of parasites were found: cestodes (Poecilancistrium caryophyllum), trematodes (Clinostomum tataxumui, Clinostomum cichlidorum), nematodes (Eustrongylides sp., Contracaecum sp.) and pentastomids (Sebekia purdieae, Sebekia sp.). Parasites infected 10 species belonging to different fish families (Ariidae, Centrarchidae, Centropomidae, Cichlidae, Eleotridae, Ictaluridae, Mugilidae and Sciaenidae). Congeneric species of parasites or related to those registered in this study have been identified as zoonotic agents in other regions of the world. Despite the low levels of infection (2.6–16.6% prevalence and 1–5.5 parasites per infected host), there is a latent risk of transmission to humans, so it is recommended to avoid eating raw or undercooked fish meat.     

Characterization of a Synechocystis sp. from Egypt with the potential of bioactive compounds production

A polyphasic approach was employed to describe a unicellular coccoid cyanobacterium isolated from Terraat El Khashab, Helwan, Egypt. The cells were characterised by their small diameter (1.9–2.2 μm) and lack of buoyancy. The cultures grew best at a temperature range of 20–40°C and moderate light intensity (20–50 μmol photon m⁻² s⁻¹). To verify its cyanobacterial nature, sequencing of 16S rRNA gene using cyanobacterial specific primers was performed followed by a phylogenetic analysis. The sequence best-matched Synechocystis sp. PCC6803 with 90% similarity. The phylogenetic analysis placed the isolate within a major clade containing different Synechocystis isolates. The fatty acid composition was rich in saturated fatty acids while polyunsaturated fatty acids were scarce. The phytochemical screening revealed the presence of flavenoids, alkaloids and saponins and absence of tannins. Vitamin C was also present in a considerable quantity. Some of the lipophilic fractions showed antimicrobial bioactivity against several pathogens. The pure bioactive compound from highest bioactive fraction was identified as oleic acid amide (M.wt.281) using chemical analyses including FT/IR, UV, proton H-NMR and GC-mass. The study highlights the importance of investigating the biotechnological potential of microorganisms inhabiting unusual niches.     

Meroterpenes from Penicillium sp found in association with Melia azedarach

A Penicillium sp was isolated from the root bark of Melia azedarach and cultivated over sterilized rice. After chromatographic procedures, two meroterpenes, named preaustinoid A and B, were obtained in addition to the known alkaloid verruculogen. Their structures were identified by extensive spectroscopic studies, and they exhibited moderate bacteriostatic effects on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus sp.     

Methoxylation pathway in biodesulfurization of model organosulfur compounds with Mycobacterium sp.

A metabolic pathway for the biodesulfurization of model organosulfur compounds e.g., dibenzothiophene (DBT), is proposed. This pathway, defined as extended 4S pathway, incorporates the traditional 4S pathway with the methoxylation pathway from 2-hydroxybiphenyl (HBP) to 2-methoxybiphenyl (2-MBP). The formation of 2-MBP was confirmed by the gas chromatography–mass spectrometry (GC–MS) analysis. A similar pathway was also obtained in the desulfurization of 4,6-dimethyldibenzothiophene (4,6-DMDBT), confirming the methoxylation reaction in the desulfurization process by the Mycobacterium sp. strain. Compared with 2-HBP, 2-MBP has much slighter inhibition effect on the cell growth and desulfurization activity. Thus, the methoxylation pathway from 2-HBP to 2-MBP would make less inhibitory effect on the microbe. The new pathway with 2-MBP as the end product may be an alternative for the further desulfuration of the fossil fuels.     

Reactivity of biologically important thiol compounds with superoxide and hydrogen peroxide.

The reactivities of glutathione, cysteine, cysteamine, penicillamine, N-acetylcysteine, dithiothreitol and captopril with superoxide generated from xanthine oxidase and hypoxanthine, and with reagent hydrogen peroxide, have been investigated. Rates of thiol loss on adding hydrogen peroxide, and superoxide-dependent thiol loss and oxygen uptake were measured. The relative reactivities of the different thiols with both oxidants were inversely related to the pK of the thiol group, such that at pH 7.4, penicillamine was the most reactive. N-acetylcysteine weakly reactive and no reaction was seen with captopril. For hydrogen peroxide, the calculated rate constants for the reaction with the thiolate anion all fell within the range 18-26 M(-1) s(-1). With superoxide, our results are consistent with each thiol reacting via a short chain that consumes oxygen and regenerates superoxide. Only with some of the thiols, was the consumed oxygen recovered as hydrogen peroxide. Reported values for the rate constant for the reaction of thiols with superoxide vary over four orders of magnitude, with the highest being > 10(5) M(-1) s(-1). Due to the complexity of the chain reaction, no study so far has been able to obtain accurate values and we consider the best estimates to be in the 30 to 1000 M(-1) s(-1) range.     

A halotolerant Alcanivorax sp. strain with potential application in saline soil remediation

Biodegradation of petroleum compounds in saline environments seems intricate and needs more attention. In this study, tetracosane was used to enrich alkane-degrading bacteria from oil-contaminated saline soils. Among the isolates, strain Qtet3, with the highest 16s rRNA gene sequence similarity to Alcanivorax dieselolei B-5^T, was able to grow at a wide range of NaCl concentrations and was shown by GC analysis to degrade more than 90% of tetracosane in 10 days. This strain has at least two alkB genes and could grow on crude oil and diesel fuel, and utilize various pure aliphatic hydrocarbon substrates (from C₁₂ to C₃₄). Highly hydrophobic cell surfaces and lack of significant surface tension reduction in the media suggest that the main mechanism of the cells for accessing substrate is to attach directly to hydrocarbon particles. Application of this strain for remediating crude oil-contaminated soils irrigated with defined saline water demonstrated that this halotolerant bacterium could survive and grow in saline soils irrigated with NaCl solutions up to 5% w/v, with the highest hydrocarbon degradation of 26.1% observed at 2.5% NaCl. This strain is promising for future industrial applications especially in bioremediation of saline soils and wastes.     

Saponins in aerial parts of Helleborus viridis L.

In the search of natural compounds inhibiting methane production in ruminants three novel steroidal saponins have been isolated from the aerial parts of Helleborus viridis L. Their structures have been established based on spectral analyses as: (25R)-26-O-β-d-glucopyranosyl-5β-furostan-3β,22α,26-triol 3-O-β-d-glucopyranosyl-(1 → 6)-O-β-d-glucopyranoside, (25R)-26-O-β-d-glucopyranosyl-5α-furostan-3β,22α,26-triol 3-O-β-d-glucopyranosyl-(1 → 6)-O-β-d-glucopyranoside and (25R)-26-O-β-d-glucopyranosyl-furost-5-ene-1β,3β,22α,26-tetraol 1-O-{α-l-rhamnopyranosyl-(1 → 2)-O-[β-d-glucopyranosyl-(1 → 3)]-6-O-acetoxy-β-d-glucopyranoside}.     

An endophytic/pathogenic Phoma sp. from creosote bush producing biologically active volatile compounds having fuel potential

A Phoma sp. was isolated and characterized as endophytic and as a pathogen of Larrea tridentata (creosote bush) growing in the desert region of southern Utah, USA. This fungus produces a unique mixture of volatile organic compounds (VOCs), including a series of sesquiterpenoids, some alcohols and several reduced naphthalene derivatives. Trans-caryophyllene, a product in the fungal VOCs, was also noted in the VOCs of this pungent plant. The gases of Phoma sp. possess antifungal properties and is markedly similar to that of a methanolic extract of the host plant. Some of the test organisms with the greatest sensitivity to the Phoma sp. VOCs were Verticillium, Ceratocystis, Cercospora and Sclerotinia while those being the least sensitive were Trichoderma, Colletotrichum and Aspergillus. We discuss the possible involvement of VOC production by the fungus and its role in the biology/ecology of the fungus/plant/environmental relationship with implications for utilization as an energy source.     

Onosma bulgarica sp. nov. (Boraginaceae–Lithospermeae) found on serpentine in Bulgaria

A new species, Onosma bulgarica (Boraginaceae–Lithospermeae), found in the eastern Rhodope Mountains in Bulgaria is described. It is a typical serpentinitophyte with local distribution and is thus a further addition to the remarkable serpentine flora. The new species belongs to the asterotrichos Onosma species and shows similarities with other endemics distributed on the Balkan Peninsula. Onosma bulgarica is clearly morphologically delimited by its suffruticose dense caespitose habit, very narrow basal and cauline leaves, bracts of lower flowers shorter than calyx and pedicel, corolla pale yellow and glabrous and short anthers. The differences between the new species and related taxa are discussed.     

Chemical potential of Aphelandra sp. cell cultures

Six different callus lines and three different suspension culture lines were established from plants of two Aphelandra species (Acanthaceae). All established lines were analyzed for secondary metabolite accumulation. A discrepancy between secondary metabolites accumulated in the plants and in the cell cultures could be observed. All established Aphelandrasp. cell cultures produced verbascoside (acteoside) as the major extractable metabolite. Time course experiments were carried out to investigate the relationship between cell growth and verbascoside production. In the present study it was shown that verbascoside accumulation was growth dependent and positively related to the presence of 2,4-D in the medium. The conditions in which verbascoside represents ca. 18% of cell culture weight have been defined. Free polyamines were detected in the cell culture lines cultivated in MS liquid medium (cysteine 10 mg l^-1, thiamine 1 mg l^-1, 2,4-D 1 mg l^-1, kinetin 0.2 mg l^-1 and sucrose 30 g l^-1). Putrescine and spermidine accumulated within 8 days to a maximum of 8.4 μmol g^-1 of dry wt and 2.6 μmol g^-1 of dry wt respectively and thereafter their concentration decreased rapidly. There was no evidence for the presence of spermine or any other type of free or conjugated polyamines in the tested cell culture lines. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nitrile-metabolizing potential of Amycolatopsis sp. IITR215

Strain Amycolatopsis sp. IITR215 was isolated from a sewage sample using polyacrylonitrile powder as the sole nitrogen source. Identification was performed by 16S rDNA analysis. The isolated strain harbored multiple nitrile-metabolizing enzymes having a wide range of substrate specificities. It metabolized nitrile and amide compounds with constitutive enzymes. Studies using an amidase inhibitor showed that hydrolysis of acrylonitrile and acrylamide occurred due to nitrile hydratase and amidase, respectively, while hydrolysis of hexanenitrile was due to the action of either nitrilase or a second nitrile hydratase/amidase system. The inhibitory effects of N-bromosuccinimide and N-ethylmaleimide on enzymes of this culture were also studied and this further indicated the involvement of either a nitrilase or a second nitrile hydratase/amidase system for hydrolysis of hexanenitrile. Interestingly, hexanenitrile hydrolysis exhibited an optimum temperature of 55 °C, whereas acrylonitrile and acrylamide hydrolysis showed an optimum temperature of 45 °C. The optimum pH was 5.8 for hexanenitrile hydrolysis and 7.0 for acrylonitrile and acrylamide hydrolysis. Hexanenitrile hydrolysis by enzymes of this strain showed better organic solvent tolerance in the presence of alcohols. The maximum enzyme activity of nitrile-metabolizing enzymes was found using media containing isobutyramide as the nitrogen source. This is the first report on constitutive multiple enzymes from the Amycolatopsis genus.     

Presence of a novel Ehrlichia sp. in Ixodes granulatus found in Okinawa, Japan

Ehrlichia -specific DNA fragments of Ehrlichia omp-1 and groEL genes were found in two I. granulatus ticks which had been collected from wild small mammals in a subtropical zone in Japan. The DNA sequences of groEL and 16SrDNA of the suspected Ehrlichia were clustered into a group of E. chaffeensis , E. muris , and Ehrlichia sp. HF565 found in I. ovatus, but were distinctly different. Therefore the Ehrlichia strain was designated as a novel Ehrlichia sp. 360. The Ehrlichia sp. 360 was detected in I. granulatus but not in any other ticks. This suggests that I. granulatus is a probable vector of Ehrlichia sp. 360 in Japan.     

合成生物聚合物的重要微生物资源-鞘氨醇单胞菌

摘要：鞘氨醇单胞菌属的许多菌株能够合成结冷胶、沃仑胶、迪特胶等多种结构相似,物理性能多样的生物聚合物,统称为鞘氨醇胶。目前,结冷胶已经大规模的生产和应用,由于鞘氨醇单胞菌属的提出仅有十几年的历史,其他种类鞘氨醇胶的研究和开发才刚刚起步。本文综述了鞘氨醇单胞菌属分类研究的最新进展,以及鞘氨醇胶的结构、特性、生物合成途径、分子遗传学和基因工程的研究现状,并对今后的研究重点和方向进行了展望。     

Wickerhamomyces tratensis sp. nov. and Candida namnaoensis sp. nov., two novel ascomycetous yeast species in the Wickerhamomyces clade found in Thailand

Two closely related yeast strains, ST-382 and ST-392, isolated in Thailand showed intermediate relatedness in the DNA-DNA hybridization experiment suggesting that the two strains represent closely related distinct species. In the tree based on the D1/D2 domain sequences of the large subunit rRNA gene, the two strains are located in a subclade in the Wickerhamomyces clade with high bootstrap support. In the D1/D2 domain, the two strains differed by two nucleotides and are assumed to be very closely related. Strain ST-392(T) (=BCC 15102(T) = NBRC 107799(T) = CBS 12176(T) forming hat-shaped ascospores is described as Wickerhamomyces tratensis sp. nov. and strain ST-382(T) (= BCC 15093(T) = NBRC 107800(T) = CBS 12175(T) is described as Candida namnaoensis sp. nov. because ascospores are not found in this strain. In phenotypic characteristics, W. tratensis and C. namnaoensis are discriminated by the ability of alcoholic fermentation and the assimilation of galactose, D-xylose and D-gluconic acid.     

Use of reduced sulfur compounds by Beggiatoa sp.

A strain of Beggiatoa cf. leptomitiformis (OH-75-B, clone 2a) was isolated which is unique among reported strains in its ability to deposit internal sulfur granules from thiosulfate. It also deposited these characteristic granules (as all BEggiatoa species do) from sulfide. In cultures where growth was limited by exhaustion of organic substrates, these granules generally comprised about 20% of the total cell weight. With medium containing acetate and thiosulfate, no measurable utilization of thiosulfate or deposition of elemental sulfur (S0) took place until after the exponential growth phase. Neither sulfide nor thiosulfate added an increment to heterotrophic growth yield except for the weight of the deposited S0. The deposition of S0 from thiosulfate was probably a disproportionation in which S0 and sulfate were produced in a 1:1 ratio. Some of the S0 was further oxidized to sulfate. No autotrophic or mixotrophic growth was demonstrated for this strain. When inoculated in small, well-dispersed quantities into yeast extract medium, this strain grew only after long lags. Addition of the enzyme catalase eliminated initial lags and increased growth rates slightly. In contrast, catalase had no influence on growth rate when added to mineral medium containing acetate. In yeast extract medium, the inhibition of growth rate was presumably because of peroxides. Addition of thiosulfate was almost as effective as catalase in eliminating this inhibition. The S0 granules which, in this case, were deposited during the exponential growth phase, appeared to be partly responsible for this relief. This strain of Beggiatoa sp. remained active for at least 5 days under strictly anaerobic conditions, and under those conditions, it increased its dry weight by about 2.5-fold. Anaerobic "growth" and maintenance required the presence of an energy source, such as acetate. When cells containing much internal S0 were transferred to an organic anaerobic medium, a substantial portion of the internal S0 was eventually converted to sulfide.