Bacterial Cellulose (BC) is still the most renewable available biopolymer produced in fine nature from alternative microbial sources as bacteria. In the present study, newly BC producing bacteria were successfully isolated from acidic fruits. The most potent producer was isolated from strawberry and identified genetically using 16 s rRNA technique as Achromobacter S3. Different fruit peels were screened to produce BC using the cheapest culture medium. Among them, Mango peel waste (MPW) hydrolysate proved to be the significant inducible alternative medium without any extra nutrients for the maximum productivity. Improvement of the BC yield was successfully achieved via statistical optimization of the MPW culture medium, from 0.52 g/L to 1.22 g/L with 2.5-fold increased about the standard HS culture medium. Additionally, the physicochemical analysis affirmed the cellulose molecular structure as well as observed the crystallinity of nanofiber as 72 and 79% for BC produced by Achromobacter S33 on HS and MPW media, respectively. Moreover, the topographical study illustrated that the BC nanofibers had close characteristics upon fiber dimeter and length as about 10 and 200 nm, respectively.

The development of new antimicrobial strategies that act more efficiently than traditional antibiotics is becoming a necessity to combat multidrug-resistant pathogens. Here we report the efficacy of laser-light-irradiated 5,10,15,20-tetrakis(m-hydroxyphenyl)porphyrin (mTHPP) loaded onto an ethylcellulose (EC)/chitosan (Chs) nanocomposite in eradicating multi-drug resistant Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans. Surface loading of the ethylcelllose/chitosan composite with mTHPP was carried out and the resulting nanocomposite was fully characterized. The results indicate that the prepared nanocomposite incorporates mTHPP inside, and that the composite acquired an overall positive charge. The incorporation of mTHPP into the nanocomposite enhanced the photo- and thermal stability. Different laser wavelengths (458; 476; 488; 515; 635 nm), powers (5–70 mW), and exposure times (15–45 min) were investigated in the antimicrobial photodynamic therapy (aPDT) experiments, with the best inhibition observed using 635 nm with the mTHPP EC/Chs nanocomposite for C. albicans (59 ± 0.21%), P. aeruginosa (71.7 ± 1.72%), and S. aureus (74.2 ± 1.26%) with illumination of only 15 min. Utilization of higher doses (70 mW) for longer periods achieved more eradication of microbial growth.

Introduction: Optimal exploitation of the huge amounts of agro-industrial residuals that are produced annually, which endangers the ecosystem and ultimately contributes to climate change, is one of the solutions available to produce value-added compounds. Aim and objectives: This study aimed at the economic production and optimization of surfactin. Therefore, the production was carried out by the microbial conversion of Potato Peel Waste (PPW) and Frying Oil Waste (FOW) utilizing locally isolated Bacillus halotolerans. Also, investigating its potential application as an antimicrobial agent towards some pathogenic strains. Results: Screening the bacterial isolates for surfactin production revealed that the strain with the highest yield (49 g/100 g substrate) and efficient oil displacement activity was genetically identified as B. halotolerans. The production process was then optimized utilizing Central Composite Design (CCD) resulting in the amelioration of yield by 11.4% (from 49 to 55.3 g/100 g substrate) and surface tension (ST) by 8.3% (from 36 to 33 mN/m) with a constant level of the critical micelle concentration (CMC) at 125 mg/L. Moreover, the physiochemical characterization studies of the produced surfactin by FTIR, ¹H NMR, and LC–MS/MS proved the existence of a cyclic lipopeptide (surfactin). The investigations further showed a strong emulsification affinity for soybean and motor oil (E24 = 50%), as well as the ability to maintain the emulsion stable over a wide pH (4–10) and temperature (10–100 °C) range. Interestingly, surfactin had a broad-spectrum range of inhibition activity against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, klebsiella pneumonia, and Candida albicans. Conclusion: Subsequently, the screening of the isolates and the utilized food-processing wastes along with the extraction technique resulted in a high yield of surfactin characterized by acceptable ST and CMC levels. However, optimization of the cultural conditions to improve the activity and productivity was achieved using Factor-At-A-Time (OFAT) and Central Composite Design (CCD). In contrast, surface activity recorded a maximum level of (33 mN/n) and productivity of 55.3 g/100 g substrate. The optimized surfactin had also the ability to maintain the stability of emulsions over a wide range of pH and temperature. Otherwise, the obtained results proved the promising efficiency of the surfactin against bacterial and fungal pathogens.

The growing spread of infectious diseases has become a potential global health threat to human beings. According to WHO reports, in this study, we investigated the impact of co-cultivating the isolated endophytic fungus Aspergillus sp. CO2 and Bacillus sp. COBZ21 as a method to stimulate the production of natural bioactive substances. (GC/MS)-based metabolomics profiling of two sponge-associated microbes, Aspergillus sp. CO2 and Bacillus sp. COBZ21, revealed that the co-culture of these two isolates induced the accumulation of metabolites that were not traced in their axenic cultures. By detection of different activities of extracts of Bacillus sp. COBZ21 and Aspergillus sp. CO2 and coculture between Bacillus sp. COBZ21 and Aspergillus sp. CO2. It was noted that the coculture strategy was the reason for a notable increase in some different activities, such as the antimicrobial activity, which showed potent activity against Escherichia coli ATCC 25,922, Staphylococcus aureus NRRLB-767, and Candida albicans ATCC 10,231. The antibiofilm activity showed significant biofilm inhibitory activity toward Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa ATCC 10,145, and Staph aureus NRRLB-767, with activity up to 53.66, 71.17, and 47.89%, while it showed low activity against E. coli ATCC 25,922, while the antioxidant activity based on the DPPH assay showed maximum activity (75.25%). GC-MS investigations revealed the presence of variable chemical constituents belonging to different chemical categories, which reflected their chemical diversity. The main components are (+-) cis-Deethylburnamine (2.66%), Bis(3,6,9,12-tetraoxapentaethylene) crowno-N,N,N’,N’-tetra methylpphanediamine (2.48%), and 11-phenyl-2,4,6,8-tetra(2-thienyl)-11-aza-5,13-dithiaeteracyclo[7.3.0.1(2,8)0.0(3,7)] trideca-3,6-diene-10,12,13-trione (3.13%), respectively, for Bacillus sp. axenic culture, Aspergillus sp. CO2, Aspergillus sp. CO2, and Bacillus sp. COBZ21 coculture. By studying the ADME-related physicochemical properties of coculture extract, the compound showed log P_o/w values above 5 (8.82). The solubility of the substance was moderate. In order to provide a comprehensive definition of medicinal chemistry and leadlikness, it is important to note that the latter did not meet the criteria outlined in the rule of three (RO3). The toxicity prediction of the coculture extract was performed using the ProTox II web server, which showed that the selected compound has no pronounced toxicity.

Among 60 isolates of Streptomyces tested; only 40 isolates were capable to utilize l-methionine as the only source of nitrogen in medium. In addition, 24 of these isolates could grow in medium amended with l-methionine as a source of nitrogen and carbon. Qualitative rapid plate assay test shows the ability of 18 of these isolates to grow with a pink color surrounding their colonial growth, while 6 of these isolates could grow and utilize l-methionine without any pink color around their colonial growth. Quantitative assay test shows the rate of l-methioninase production by all isolates tested. Permeabilization treatment including chemical and physical methods proved that l-methioninase was found to be extracellularly produced. The results also indicate that l-methioninase production was not correlated with growth rate or l-methionine consumption in medium. On the other hand, quantitative assay test shows that these six isolates were l-methioninase negative and failed to produce any amount of l-methioninase. In addition, results also show that isolates No. 4 and No. 60 were the most suitable for l-methioninase production, these two isolates were characterized and identified as Streptomyces sp. DMMMH 4 and Streptomyces sp. MDMMH 60 using 16S rRNA with accession No. in gene bank. Furthermore, optimal conditions for enzyme activity produced by the two isolates were established in relation to temperature, pH, reaction time and type of buffer used and its molarities.

Purification of L-methionine γ-lyase (MGL) from A. fumigatus was sequentially conducted using heat treatment and gel filtration, resulting in 3.04 of purification fold and 73.9% of enzymatic recovery. The molecular mass of the purified MGL was approximately apparent at 46 KDa based on SDS-PAGE analysis. The enzymatic biochemical properties showed a maximum activity at pH 7 and exhibited plausible stability within pH range 5.0–7.5; meanwhile the highest catalytic activity of MGL was observed at 30–40 °C and the enzymatic stability was noted up to 40 °C. The enzyme molecule was significantly inhibited in the presence of Cu²⁺, Cd²⁺, Li²⁺, Mn²⁺, Hg²⁺, sodium azide, iodoacetate, and mercaptoethanol. Moreover, MGL displayed a maximum activity toward the following substrates, L-methionine < DL-methionine < Ethionine < Cysteine. Kinetic studies of MGL for L-methioninase showed catalytic activity at 20.608 mM and 12.34568 µM.min⁻¹. Furthermore, MGL exhibited anticancer activity against cancerous cell lines, where IC₅₀ were 243 ± 4.87 µg/ml (0.486 U/ml), and 726 ± 29.31 µg/ml (1.452 U/ml) against Hep-G2, and HCT116 respectively. In conclusion, A. fumigatus MGL had good catalytic properties along with significantly anticancer activity at low concentration which makes it a probably candidate to apply in the enzymotherapy field.