Bioactive natural products from Pseudonocardia endophytica VUK-10

Genus Pseudonocardia: What we know about its biological properties, abilities and current application in biotechnology

The genus Pseudonocardia belongs to a group of Actinomycetes, and is a member of the family Pseudonocardiacea. The members of this genus are aerobic, Gram-positive, non-motile bacteria that are commonly found in soil, plant and environment. Although this genus has a low clinical significance; however, it has an important role in biotechnology due to the production of secondary metabolites, some of which have anti-bacterial, anti-fungal and anti-tumour effects. The use of phenotypic tests, such as gelatinase activity, starch hydrolysis, catalase and oxidase tests, as well as molecular methods, such as polymerase chain reaction, are necessary for Pseudonocardia identification at the genus and species levels.

Deciphering Trifolium pratense L. holobiont reveals a microbiome resilient to future climate changes

The plant microbiome supports plant growth, fitness, and resistance against climate change. Trifolium pratense (red clover), an important forage legume crop, positively contributes to ecosystem sustainability. However, T. pratense is known to have limited adaptive ability toward climate change. Here, the T. pratense microbiomes (including both bacteria and fungi) of the rhizosphere and the root, shoot, and flower endospheres were comparatively examined using metabarcoding in a field located in Central Germany that mimics the climate conditions projected for the next 50-70 years in comparison with the current climate conditions. Additionally, the ecological functions and metabolic genes of the microbial communities colonizing each plant compartment were predicted using FUNGuild, FAPROTAX, and Tax4Fun annotation tools. Our results showed that the individual plant compartments were colonized by specific microbes. The bacterial and fungal community compositions of the belowground plant compartments did not vary under future climate conditions. However, future climate conditions slightly altered the relative abundances of specific fungal classes of the aboveground compartments. We predicted several microbial functional genes of the T. pratense microbiome involved in plant growth processes, such as biofertilization (nitrogen fixation, phosphorus solubilization, and siderophore biosynthesis) and biostimulation (phytohormone and auxin production). Our findings indicated that T. pratense microbiomes show a degree of resilience to future climate changes. Additionally, microbes inhabiting T. pratense may not only contribute to plant growth promotion but also to ecosystem sustainability.

Isolation of 2,5-diketopiperazines from Lysobacter capsici AZ78 with activity against Rhodococcus fascians

Inhibitory activity of the biocontrol bacterial strain Lysobacter capsici AZ78 is related to the production of cyclo(l-Pro-l-Tyr), a 2,5-diketopiperazine with in vitro and in vivo toxic activity against Phytophthora infestans and Plasmopara viticola. Further investigation of culture filtrate organic extracts showed its ability to produce other 2,5-diketopiperazines. They were isolated and identified by spectroscopic (¹H NMR and ESIMS) and physic (specific optical rotation) methods as cyclo(l-Pro-l-Val), cyclo(d-Pro-d-Phe), cyclo(l-Pro-l-Leu), and cyclo(d-Pro-l-Tyr). When tested against the phytopathogenic Gram-positive bacterium Rhodococcus fascians LMG 3605, cyclo(l-Pro-l-Val) showed a toxic activity similar to chloramphenicol at a comparable concentration. Overall, these data suggest that 2,5-diketopiperazines represent a class of metabolites characterizing the metabolome of L. capsici AZ78. Furthermore, the toxic activity showed by cyclo(l-Pro-l-Val) against R. fascians LMG 3605 broaden the spectrum activity of 2,5-diketopiperazines against phytopathogenic microorganisms enforcing their potential development as biopesticides.[Formula: see text].

Antibiotics Development and the Potentials of Marine-Derived Compounds to Stem the Tide of Multidrug-Resistant Pathogenic Bacteria, Fungi, and Protozoa

As the search for new antibiotics continues, the resistance to known antimicrobial compounds continues to increase. Many researchers around the world, in response to antibiotics resistance, have continued to search for new antimicrobial compounds in different ecological niches such as the marine environment. Marine habitats are one of the known and promising sources for bioactive compounds with antimicrobial potentials against currently drug-resistant strains of pathogenic microorganisms. For more than a decade, numerous antimicrobial compounds have been discovered from marine environments, with many more antimicrobials still being discovered every year. So far, only very few compounds are in preclinical and clinical trials. Research in marine natural products has resulted in the isolation and identification of numerous diverse and novel chemical compounds with potency against even drug-resistant pathogens. Some of these compounds, which mainly came from marine bacteria and fungi, have been classified into alkaloids, lactones, phenols, quinones, tannins, terpenes, glycosides, halogenated, polyketides, xanthones, macrocycles, peptides, and fatty acids. All these are geared towards discovering and isolating unique compounds with therapeutic potential, especially against multidrug-resistant pathogenic microorganisms. In this review, we tried to summarize published articles from 2015 to 2019 on antimicrobial compounds isolated from marine sources, including some of their chemical structures and tests performed against drug-resistant pathogens.

Bioactive compounds from mangrove derived rare actinobacterium Saccharomonospora oceani VJDS-3

A rare actinobacterium was isolated from Nizampatnam mangrove ecosystem of Andhra Pradesh, India, and was screened for its ability to produce bioactive compounds. The potential strain was identified as Saccharomonospora oceani VJDS-3 by polyphasic taxonomy. Purification of the biologically active compounds by column chromatography led to the isolation of three compounds, namely methoxy ethyl cinnamate (ethyl(E)-3-(4-methoxyphenyl)acrylate) (R1), 4-hydroxy methyl cinnamate (methyl(E)-3-(4-hydroxyphenyl)acrylate) (R2) and 4-methylbenzoic acid (R3). The structure of the compounds was elucidated on the basis of spectroscopic analysis including FTIR, EIMS, 1HNMR and 13CNMR spectroscopies. The antimicrobial activity of the bioactive compounds produced by the strain was tested against a panel of bacteria and fungi, and expressed in terms of minimum inhibitory concentration. Compound (R1) exhibited higher antimicrobial potential (50 µg/ml) against Staphylococcus aureus, Bacillus megaterium and Candida albicans compared to R2 and R3. Antioxidant activity of compounds was determined by DPPH and ABTS radical scavenging activities. The results revealed that compound R3 effectively scavenged DPPH (73.08 ± 1.29) and ABTS (99.74 ± 0.00) radicals at a concentration of 25 and 50 µg/ml, respectively. Antidiabetic and anti-obesity activities were evaluated by inhibitory potential of compounds against alpha-glucosidase, alpha-amylase and pancreatic lipase by spectrophotometric assays. Compound R1 showed effective inhibition against alpha-glucosidase (66.8 ± 1.2) at 20 µg/ml while moderate to weak activities were found against alpha-amylase and pancreatic lipase. To the best of our knowledge, this is the first report on the isolation of supra said compounds from the genus Saccharomonospora.