Extraction optimization and quality evaluation of humic acids from lignite using the cell-free filtrate of Penicillium ortum MJ51

Bio-solubilization of lignite is a promising technology to transform coal into humic acids (HAs) which are broadly used in agriculture.

On the Synergism of Biogenic Gold Nanoparticles and Hydroxyaluminum Phthalocyanines in the Photoeradication of Staphylococcus aureus

Due to the unusual properties of gold nanoparticles, these structures are widely used in medicine and biology. This paper describes for the first time the synthesis of colloidal gold nanoparticles by the cell-free filtrate obtained from the Coriolus versicolor biomass and the use of these biogenic nanostructures to increase the photosensitizing efficiency of di- (AlPcS2) and tetrasulfonated (AlPcS4) hydroxyaluminum phthalocyanines in antibacterial photodynamic therapy. The obtained monodisperse particles were extremely stable, and this remarkable stability was due to the presence of phosphoprotein as a capping agent. The studied gold nanoparticles had a spherical shape, were uniformly distributed, and were characterized by a single plasmon band at wavelength of 514–517 nm. Almost 60% of the gold particles were found to be in the range of 13 to 15 nm. In accordance with the regulations of the American Microbiological Society, indicating that any antimicrobial technique must kill at least 3 log CFU (99.9%) to be accepted as “antimicrobial”, this mortality of Staphylococcus aureus was shown to be achieved in the presence of AlPcS4 + AuNPs mixture and 4.8 J cm−2 light dose compared to AlPcS4 alone, which required a light dose of 24 J cm−2. The best effect of increasing the effectiveness of combating this pathogen was observed in the case of AlPcS2 + AuNPs as a photosensitizing mixture. The light dose of 24 J cm−2 caused a lethal effect of the studied coccus in the planktonic culture.

Biogenic Synthesis of Silver Nanoparticles Mediated by the Consortium Comprising the Marine Fungal Filtrates of Penicillium Oxalicum and Fusarium Hainanense Along With Their Antimicrobial, Antioxidant and Larvicidal Potency

The silver nanoparticles were biosynthesized using fungal isolates as well as their mixed cell free filtrate acting as a consortium namely, DS-2 (Penicillium oxalicum), DW-8 (Fusarium hainanense) and DSW-28, respectively. The UV-Visible spectra determined the surface plasmon resonance at 438, 441 and 437 nm for the silver nanoparticles synthesized by DS-2, DW-8 and DSW-28, respectively. The Tauc’s plot analysis disclosed the band gap energy between 2.21 eV to 2.24 eV which depicted their ability to act as a semiconductor. The TEM imaging revealed the spherical shape along with the average particle size of DS-2 as 11.14 ± 2.39 nm and DW-8 as 7.59 ± 1.31 nm whereas that of DSW-28 as 5.73 ± 0.4 nm. Thus, the silver nanoparticles synthesized by DSW-28 were smaller in size than the individual isolates. The XRD pattern of the silver nanoparticles exhibited the crystalline structure corresponding to their peaks. The FTIR spectra indicates the presence of different functional groups on the surface of the synthesized silver nanoparticles. The broad-spectrum antimicrobial activity was exhibited by silver nanoparticles synthesized by DSW-28 against Gram positive, Gram negative bacteria and plant pathogen Fusarium oxysporum than the individual fungal isolates. The DSW-28 synthesized silver nanoparticles also acts as an effective antioxidant by depicting their radical scavenging activity against DPPH. Moreover, the silver nanoparticles synthesized by DSW-28 also inhibited the growth of 4th instar larvae of Aedes aegypti and Culex quinquefasciatus more efficiently than DS-2 and DW-8 in a dose-dependent method. The impressive bioactivity of the silver nanoparticles synthesized by the mixture of cell free filtrate of various fungi acting as a consortium recommends their prospective use in agriculture as well as in biomedical as an antimicrobial, antioxidant and larvicidal agents in future.

Streptomyces botrytidirepellens sp. nov., a novel actinomycete with antifungal activity against Botrytis cinerea

The fungal pathogen Botrytis cinerea is the causal agent of devastating gray mold diseases in many economically important fruits, vegetables, and flowers, leading to serious economic losses worldwide. In this study, a novel actinomycete NEAU-LD23T exhibiting antifungal activity against B. cinerea was isolated, and its taxonomic position was evaluated using a polyphasic approach. Based on the genotypic, phenotypic and chemotaxonomic data, it is concluded that the strain represents a novel species within the genus Streptomyces , for which the name Streptomyces botrytidirepellens sp. nov. is proposed. The type strain is NEAU-LD23T (=CCTCC AA 2019029T=DSM 109824T). In addition, strain NEAU-LD23T showed a strong antagonistic effect against B. cinerea (82.6±2.5%) and varying degrees of inhibition on nine other phytopathogenic fungi. Both cell-free filtrate and methanol extract of mycelia of strain NEAU-LD23T significantly inhibited mycelial growth of B. cinerea. To preliminarily explore the antifungal mechanisms, the genome of strain NEAU-LD23T was sequenced and analyzed. AntiSMASH analysis led to the identification of several gene clusters responsible for the biosynthesis of bioactive secondary metabolites with antifungal activity, including 9-methylstreptimidone, echosides, anisomycin, coelichelin and desferrioxamine B. Overall, this research provided us an excellent strain with considerable potential to use for biological control of tomato gray mold.

Different Concentrations of Lactobacillus acidophilus Cell Free Filtrate Have Differing Anti-Biofilm and Immunomodulatory Effects

Probiotics such as various strains of Lactobacillaceae have been shown to have antimicrobial and immunomodulatory activity. In vitro studies have shown that Lactobacilli can decrease bacterial biofilm formation. Effects on immune cells have been unclear with most studies showing anti-inflammatory activity. The mechanism of effects has not been clearly elucidated. In these studies, we used different concentrations of live Lactobacillus acidophilus as well as cell free filtrate (CFF) derived from different concentrations of bacteria. Use of CFF is advantageous as a therapeutic because in vivo it can directly contact immune cells and its concentration is fixed. Both live cells and CFF inhibited Pseudomonas aeruginosa biofilm formation. Importantly, we show that high concentration CFF destroyed mature biofilm. This activity was not due to a lowered pH per se, as pH matched HCl did not remove mature biofilm. High concentration CFF totally inhibited P. aeruginosa growth and was bactericidal (>99.99%), but low concentration CFF was not bactericidal. To examine the immunomodulatory effects of L. acidophilus, we incubated THP-1 monocytes and derived macrophages with CFF and measured TNFα production. CFF did not significantly increase TNFα production in THP-1 monocytes. When cells were prestimulated with LPS, high concentration CFF increased TNFα production even further. In macrophages, high concentration CFF alone increased TNFα production but did not affect LPS prestimulated cells. In contrast, low concentration CFF decreased TNFα production in LPS prestimulated cells. To elucidate the possible mechanisms for these effects, we repeated the experiments using a NF-κB reporter THP-1 cell line. High concentration CFF increased NF-κB activity in monocytes and macrophages. In LPS prestimulated macrophages, only low concentration CFF reduced NF-κB activity. These results suggest that high concentration CFF alone induced NF-κB expression which could account partially for an increase in TNFα production. On the other hand, in macrophages, the lower non-bactericidal concentration of CFF reduced NF-κB expression and decreased TNFα production after LPS prestimulation. Taken together, the results provide evidence that different concentrations of L. acidophilus CFF possess varying bactericidal, anti-biofilm and immunomodulatory effects. This is important in vivo to evaluate the possible use of L. acidophilus CFF in different conditions.

Study on the antifungal effect and mycolytic activity of the biocontrol agent Chaetomium subaffine LB-1

The antifungal effect and mucolytic activity of a newly screened biocontrol strain Chaetomium subaffine LB-1 were researched in this study. The results found that LB-1 has good antifungal effects on the test plant pathogenic fungi Botrytis cinerea Pers. ex Fr., Fusarium oxysporum f. sp. cucumerinum Owen and Alternaria solani (Ellis & Martin) Sorauer in dual culture assay, with the inhibition rates of 61.39, 50.34 and 51.22%, respectively. Flocculated and dissolved hyphae of the phytopathogenic fungi were observed at the interaction zone on a dual-cultured PDA plate, but the hyphae of LB-1 were normal. The LB-1 cell-free filtrate has significant inhibitory effects on the three tested fungi in the poison plate assay; dissolved colonies, vesiculated and flocculated hyphae of the test pathogenic fungi were also found on the PDA plates supplemented with the LB-1 cell-free filtrate. Clear halo zones around the LB-1 colonies were found on the protease test plate, pectinase test plate and cellulose test plate, indicating that LB-1 could produce mucolytic enzymes of protease, pectinase and cellulase. However, the activities of chitinase and β-l,3-glucase were not detected on their test plates from LB-1. An obvious oil-displaced circle was formed in the oil spreading test, indicating that a surface-active substance might be contained in the LB-1 cell-free filtrate. These results proved that the biocontrol agent of C. subaffine LB-1 could exert its antifungal effects via living competition and mycolysis, and the latter may be obtained by production of mycolytic enzymes and surface-active substances. .

Optimization of mycobiosynthesis of silver nanoparticles by using Fusarium 4F1 and Trichoderma TRS isolates

Silver nanoparticles (Ag-NPs) by mixing silver nitrate (AgNO3) with cell-free filtrate (CFF) of the two fungal isolates viz., Fusarium 4F1 and Trichoderma TrS were synthesized. pH, substrate concentration and incubation period for the production of better quality and quantity of Ag-NPs was optimized. The Ag-NPs by UV-vis spectroscopy were characterized. Between the two fungal isolates, pH levels, AgNO3 concentrations and incubation periods studied, the highest number of spherical shaped, monodispersed and stable Ag-NPs were recorded from Fusarium 4F1 at pH 9, 2 mM AgNO3 and 72 hrs of incubation.

Potential antagonistic rhizobacteria to control Colletotrichum scovillei, the cause of anthracnose disease in chili pepper

Darmadi AAK, Suprapta DN, Khalimi K. 2020. Potential antagonistic rhizobacteria to control Colletotrichum scovillei, the cause of anthracnose disease in chili pepper. Biodiversitas 21: 2727-2734. Six species of Colletotrichum were identified as the cause of anthracnose disease on Bali Island, Indonesia in 2018. These species were C. scovillei, C. acutatum, C. nymphaeae, C. gloesporioides, C. truncatum, and C. fructicola. Among them, C. scovillei was the most prevalent at 55% of all samples tested. This study was conducted to find potential antagonistic rhizobacteria isolated from various rhizospheres of plants grown in Bali. A total of 1,040 rhizobacteria isolates were tested for their antagonistic activity against the growth of C. scovillei on potato dextrose agar. Results showed that 10 isolates inhibited the growth of C. scovillei by more than 80%. Among these isolates C1 and C7B possessed inhibitory activity at 94.9% and 94.3%, respectively. Molecular identification based on analysis of 16S rRNA gene showed that isolate C1 belonged to the species Paenibacillus polymyxa, whereas isolate C7B was identified as Bacillus siamensis. According to scanning electron serious damage on mycelia of C. scovillei was observed. Wrinkles were observed on mycelia of C. scovillei grown jointly with rhizobacterial isolate C1, whereas no wrinkle was observed on C. scovillei grown solely. Three compounds were detected in the hexane phase of cell-free filtrate P. polymyxa C1, namely, 3-hydroxy-2-butanone and 2,3-butanediol. These compounds may be responsible for antifungal activity against C. scovillei.

Assessment of the Allelochemical Activity and Biochemical Profile of Different Phenotypes of Picocyanobacteria from the Genus Synechococcus

Organisms belonging to Synechococcus sp. genera are observed in all freshwater, brackish, and marine waters of the world. They play a relevant role in these ecosystems, since they are one of the main primary producers, especially in open ocean. Eventually, they form mass blooms in coastal areas, which are potentially dangerous for the functioning of marine ecosystems. Allelopathy could be an important factor promoting the proliferation of these organisms. According to the authors’ best knowledge, there is no information on the allelopathic activity and allelopathic compounds exhibited by different Synechococcus sp. phenotypes. Therefore, the research conducted here aimed to study the bioactivity of compounds produced by three phenotypes of Synechococcus sp. by studying their influence on the growth, chlorophyll fluorescence, and photosynthetic pigments of eighteen cyanobacteria and microalgae species. We demonstrated that three different Synechococcus sp. phenotypes, including a phycocyanin (PC)-rich strain (Type 1; green strain) and phycoerythrin (PE)-rich strains containing phycoerythrobilin (PEB) and phycocyanobilin (PCB) (Type 2; red strain and Type 3a; brown strain), had a significant allelopathic effect on the selected species of cyanobacteria, diatoms, and green algae. For all green algae, a decrease in cell abundance under the influence of phenotypes of donor cyanobacteria was shown, whereas, among some target cyanobacteria and diatom species, the cell-free filtrate was observed to have a stimulatory effect. Our estimates of the stress on photosystem II (Fv/Fm) showed a similar pattern, although for some diatoms, there was an effect of stress on photosynthesis, while a stimulatory effect on growth was also displayed. The pigment content was affected by allelopathy in most cases, particularly for chlorophyll a, whilst it was a bit less significant for carotenoids. Our results showed that Synechococcus sp. Type 3a had the strongest effect on target species, while Synechococcus sp. Type 1 had the weakest allelopathic effect. Furthermore, GC-MS analysis produced different biochemical profiles for the Synechococcus strains. For every phenotype, the most abundant compound was different, with oxime-, methoxy-phenyl- being the most abundant substance for Synechococcus Type 1, eicosane for Synechococcus Type 2, and silanediol for Synechococcus Type 3a.