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Fungal-bacterial co-culturing is a potential technique for the production of secondary metabolites with antibacterial activity. Twenty-nine fungal species were screened in a co-culture with carbapenem-resistant Klebsiella pneumoniae at different temperatures. A temperature of 37 ° showed inhibition of bacterial growth. Antimicrobial susceptibility testing for K. pneumoniae was conducted to compare antibiotic resistance patterns before and after the co-culture. Genotypic comparison of the K. pneumonia was performed using next generation sequencing (NGS). It was shown that two out of five K. pneumoniae , with sequence type ST 101 isolates, lost bla- OXA48 , bla- CTX-M-14 , tir , strA and strB genes after the co-culture with Scopulariopsis brevicaulis fungus. The other three isolates (ST 383 and 147) were inhibited in the co-culture but did not show any changes in resistance. The total ethyl acetate extract of the fungal-bacterial co-culture was tested against K. pneumoniae using a disc diffusion method. The concentration of the crude extract was 0.97 mg/µL which resulted in total inhibition of the bacteria. Using chromatographic techniques, the purified compounds were identified as 11-octadecenoic acid, 2,4-Di-tert-butylphenol, 2,3-Butanediol and 9-octadecenamide. These were tested against K. pneumoniae using the well diffusion method at a concentration of 85 µg/µL which resulted in total inhibition of bacteria. The co-culture results indicated that bacteria under chemical stress showed variable responses and induced fungal secondary metabolites with antibacterial activities.

Gum arabic (GA) is a traditional herbal medicine from Acacia Senegal (L.) Willdenow trees, which consist of a complex mixture of polysaccharides and glycoproteins. It is used in daily applications for several diseases and is considered to protect against bacterial infections. The detailed mechanisms behind these observations are still unclear. In this study, we investigated the direct antibacterial activity of GA water and ethanol extracts against Staphylococcus ( S .) aureus or Escherichia ( E .) coli and the immunomodulating properties of those extracts on granulocytes as a first line of defense against bacteria. Firstly, the direct antimicrobial effect of GA was tested on three different S. aureus strains and two E. coli strains. The growth of bacteria was analyzed in the presence of different GA concentrations over time. GA water as well as ethanol extracts showed a significant growth inhibition in a concentration-dependent manner in the case of S. aureus Newman, S. aureus Rd5, and E. coli 25922, but not in the case of S . aureus USA300 and E. coli K1. Transmission electron microscopic analysis confirmed an antibacterial effect of GA on the bacteria. Secondly, the immunomodulatory effect of GA on the antimicrobial activity of bovine or human blood-derived granulocytes was evaluated. Interestingly, water and ethanol extracts enhanced antimicrobial activity of granulocytes by the induction of intracellular ROS production. In line with these data, GA increased the phagocytosis rate of E. coli . No effect was seen on neutrophil extracellular trap (NET) formation that mediates killing of extracellular bacteria such as S. aureus . In conclusion, we show that GA exhibits a direct antibacterial effect against some S. aureus and E. coli strains. Furthermore, GA boosts the antimicrobial activities of granulocytes and increases intracellular ROS production, which may lead to more phagocytosis and intracellular killing. These data might explain the described putative antimicrobial activity of GA used in traditional medicine., (Copyright © 2020 Baien, Seele, Henneck, Freibrodt, Szura, Moubasher, Nau, Brogden, Mörgelin, Singh, Kietzmann, von Köckritz-Blickwede and de Buhr.)

Given the upwelling of a variety of potential applications laccases could participate in, it would be fitting to equally make available laccases that are well suited for the aforementioned. Therefore historian understanding of the catalytic and physicochemical properties is desirable. Owing to this, the biochemical properties of the crude laccases from Achromobacter xylosoxidans HWN16 (Hb9c) and Citrobacter freundii LLJ 16 (Ie1c) were assessed. Furthermore, a hint of the molecular basis for their production from respective organisms was presented. Results showed that both laccases were tolerant, and sometimes had their activities improved by the set of parameters tested. They were active at broad range of temperature (0-90 °C), pH (3-11), and were equally thermo- and pH-stable. Their activities were either improved, or left unabated by cations, detergents, and chloride (5-40%), however, the highlight of the study was their augmented activity, when they were incubated with certain concentrations of fluoride (2-20%), a potent inhibitor. They were depicted to have multiple homologous laccase encoding genes, on molecular evaluation, which may be responsible the conferral of these remarkable qualities they possess. Therefore, the laccases might be beneficial, if employed in formulations for a wide range of environmental and biotechnological applications. Moreover, the molecular machinery of their production be exploited for economical benefits in the immediate future.

The increasing occurrence of antibiotic-resistant Staphylococcus ( S .) aureus tremendously limits the antibiotic-based treatment options; therefore, an open discussion of alternative treatment strategies is urgently needed. The use of naturally derived materials might become a more promising concept, not only as directly acting antimicrobials, but also for stimulation of the immune system. Costa Rican plant extracts were screened for their ability to enhance the antimicrobial activity of human blood-derived cells against S. aureus infections. We identified three plant extracts which significantly reduced the growth of S. aureus in the presence of human blood without directly acting as antibacterials: Byrsonima crassifolia acetone bark extract, Mandevilla veraguasensis acetone vine extract and Verbesina oerstediana acetone bark extract (VEOEBA). The effect of VEOEBA was studied in more detail, and revealed that VEOEBA increases the antimicrobial activity of neutrophils by enhancing the formation of neutrophil extracellular traps., Competing Interests: The authors declare no conflict of interest.

The conditions for the sulfhydryl oxidase (SOX) production and activity from an Egyptian isolate of Aspergillus niger were optimized. Purification and determination of the kinetic properties (K(m) and V(max)) of the purified enzyme have been done. The possibility for the SOX induction using L-Cys (as a natural substrate) was studied to determine whether SOX could be produced as an inducible enzyme in addition to being a constitutive one (i.e. whether induction leads to increase SOX production and activity or not). The optimum temperature and pH for its activity were found to be 60 degrees C and 5.5, respectively. The activity of the induced intracellular SOX, was measured according to Ellman's method using the standard GSH oxidation where it reached 94% while that of non-induced one reached only 27.6%. This wide difference in activity between the induced and non-induced SOX indicates the successful L-Cys-induction of the SOX production (i.e. SOX from A. niger AUMC 4947 is an inducible enzyme). Molecular characterization of the pure SOX revealed that it is constituted of two 50-55 KDa subunits. K(m) and V(max) were found to be 6.0 mM and 100 microM/min/mg respectively.