An experimental study of the investigation of post-harvest fungal control potential of natamycin-loaded chitosan nanoparticles: synthesis, characterization, and antifungal activity analyses.

Introduction Healthcare associated infection (HAI) is global health problem and main reasons behind these infections are suboptimal infection control practices along with excessive antibiotics consumption [1]. On the other hand, environmental factors including inadequate ventilation, bed spacing, contaminated water supply, environmental surfaces and improper disposal of waste are other concerns. The HAI risk can be minimized by implementation of infection prevention and control program, which is comprised of activities directed to dig out problems and applying various techniques to bring about a change in healthcare workers attitude in order to improve infection control practices [2].In the last decade infection prevention and control at hospital has been significantly improved globally. Measures such as hand hygiene, environmental cleaning, culture based screening are implemented in order to minimize hospital stay, morbidity and mortality. Objective The study was conducted to compare the difference in infection control at our hospital before and after taking measurement at our newly established centre. Material and Method It was an analytical cross-sectional study carried out at our new campus. The study was conducted from February 2018 to January 2019.Ethical approval was taken from research committee prior to the study and informed consent was taken from the patients and staff. The study was fabricated in two phases i.e. initial and later six months of hospital establishment. Based on the results obtained in the initial six months, we assigned an infection control team, along with facilitation of training sessions for our staff. Culture samples were taken from patients, patient’s rooms, patient’s wards, accessories inside the patient’s room, from counters and corridors. Blood cultures were performed using the BACTEC blood culture system. Organisms were identified according to routine bacteriological procedures and disc diffusion method was used for interpreting antibiotic susceptibility. Data were included cultures reports taken from the laboratory. For statistical analysis, SPSS version 23.0 was used. Descriptive statistics was applied for categorical variables and Chi square test was used to observe the association with significance level as p=<0.05. Results A total of 1151 cultures were sent including patients, staff and environmental cultures. Out of which 681 (59%) were sent in initial phase and 470 (41%) were sent in later phase. The number of samples sent in initial and later phase and its distribution is depicted in Table 1. The growth of organisms was observed in initial and later phase from the samples and it was found out that there was increased rate of fungal growth in environment cultures in initial and later phase. In majority of the patient’s samples, no bacterial growth was reported in initial and later phase. (Table 2)Overall, absence of any organisms was found to be statistically same in both phases. However, bacterial and fungal growth reduced in later than the initial phase and the reduction in fungal growth was statistically significant as shown in Table 3 The samples taken from the patients and environment in initial and later phase were compared and are depicted in table 4. The growth of organism from the environment, accessories inside the patient’s room, nursing counter, and patients was found statistically non-significant. Conclusion Our study revealed that the number of organisms isolated in initial phase was greater than the later phase but the reduction was not significant. Bringing about a change in healthcare workers attitude is always a big challenge. Constant reinforcement is impending for compliance of healthcare professionals towards infection control and prevention. Referernces 1) Shelanah A. Fernando GT, Thomas G. Healthcare-acquired infections: prevention strategies. Int J Gen Med 2017; 47:1341-51. 2) Lee MH, Lee GA, Lee SH, Park YH. Effectiveness and core components of infection prevention and control programmes in long-term care facilities: a systematic review. J Hosp Infect 2019; 102: 377-393

Biocontrol using plant growth-promoting rhizobacteria (PGPR) represents an alternative approach to disease management, since PGPR are known to promote growth and reduce diseases in various crops. Among the different PGPR, members of the genus Bacillus are prefered for most biotechnological uses due to their capability to form extremely resistant spores and produce a wide variety of metabolites with antimicrobial activity. The objective of this research was to identify antagonistic bacteria for management of the plant diseases. Eleven isolates of Bacillus spp. were obtained from the soil samples collected from different localities in the Province of Vojvodina. The antifungal activity of bacterial isolates against five fungal species was examined using a dual plate assay. Bacillus isolates exhibited the highest antifungal activity against Fusarium proliferatum, Fusarium oxysporum f. sp. cepae and Alternaria padwickii, while they had the least antagonistic effect on Fusarium verticillioides and Fusarium graminearum. Molecular identification showed that effective bacterial isolates were identified as Bacillus safensis (B2), Bacillus pumilus (B3, B11), Bacillus subtilis (B5, B7) and Bacillus megaterium (B8, B9). The highest antagonistic activity was exhibited by isolates B5 (from 39% to 62% reduction in fungal growth) and B7 (from 40% to 71% reduction in fungal growth). These isolates of B. subtilis could be used as potential biocontrol agents of plant diseases.

Currently, the attention of researchers is directed towards microalgae and cyanobacteria due to their use as an alternative source of antibiotics. Among the first isolated antimicrobial compounds is chlorelin, from Chlorella sp. which is a mixture of fatty acids that inhibits the growth of both gram-positive and gramnegative bacteria. Eicosapentaenoic acid, hexadecatrienoic acid and palmitoleic acid isolated from Phaeodactylum tricornutum have been shown to possess antimicrobial activity against Staphylococcus aureus gram-positive strain. Thus, the aim of the research was to determine the antifungal activity of 8 strains of microalgae, isolated from the lake "La Izvor". The cultures were isolated by inoculation on liquid and solid mineral nutrient media. Hydroalcoholic extracts (60-70%) from microalgae biomass were used to determine the antifungal activity against phytopathogenic cultures of fungi. Thus, the experiments showed that microalgae strains have antifungal activity against the tested cultures of pathogenic fungi, especially Oscillatoria acutissima and Spirulina major showed a clear inhibitory effect (diameter of inhibition zone more -24mm and 25mm, respectively) against Alternaria alternata. Biomass extracts of O. planctonica, O. brevis (diameter of the inhibition zone of 40 mm) O. acutissima and Chlorella vulgaris, have shown an inhibitory effect on the growth of Aspergillus niger and Botrytis cinerea. An inhibitory action on the growth of the pathogenic fungus Fusarium solani, have presented extracts from O. planctonica, O. acutissima, S. major, Anabaena variabilis and Nostoc verrucosum.

Additive and synergistic effects of Bacillus spp. isolates and essential oils on the control of phytopathogenic and saprophytic fungi from medicinal plants and marigold seeds

Aqueous, ethanol and n-hexane extracts from leaves, fruit, root-bark and stem-bark of Syzygium cumini (L.) Skeels were tested for their antifungal activity against Ascochyta rabiei (Pass.) Lab., the cause of blight disease of the chickpea (Cicer arietinum L.). Different concentrations, namely 1, 2, …, 5% of both aqueous and the two organic solvent extracts were used in this study. Aqueous extracts of all the four test plant parts, namely leaves, fruit, stem-bark and root-bark, showed significant antifungal activity resulting in 7–30%, 22–59%, 23–39% and 21–64% reduction in fungal growth, respectively. Similarly, n-hexane stem-bark extract, and ethanol root- and stem-bark extracts also significantly suppressed the growth of target fungal species, resulting in 17–39%, 24–30% and 12–32% suppression in fungal growth.

Antifungal and antimycotoxigenic activity of hydrolyzed goat whey on Penicillium spp: An application as biopreservation agent in pita bread

Two experiments were undertaken to determine the effect of agar amendments on the growth of the asexual (anamorph) stage of the entomopathogenic fungus Ophiocordyceps robertsii (Hook.) G.H. Sung, J.M. Sung, Hywel-Jones & Spatafora (Hypocreales:Ophiocordycipitaceae) in culture. These were part of ongoing research whose aim was to develop methods for augmenting O. robertsii infested ghost moth (Hepialidae) larvae (āwheto) populations in forests, with a view to assisting their potential commercial harvest. The first experiment used full-strength potato-dextrose agar (PDA) with added yeast while the second used a reduced concentration of PDA. Amendments included mycosed host (ghost moth larva) tissue, leaf litter, soil, hinau (Elaeocarpus dentatus (J.R.Forst. et G.Forst.) Vahl var. dentatus) leaves, berries, seeds and roots and combinations of these amendments. The hinau leaf amendment treatment stood out, unexpectedly causing a 53% reduction in fungal growth in the first experiment and a 100% reduction in the second. Several of the other amendments were associated with a small (up to 15%) reduction in fungal growth in both experiments while in the second experiment, with a reduced-agar content, some combinations of amendments that avoided the use of hinau leaves were associated with an increase in fungal growth of 24%–43%. While these experiments did not achieve the original objectives of developing amended media recipes for increasing O. robertsii growth rates, they do indicate that hinau leaves may contain chemicals with anti-fungal properties. The results are discussed in relation to recent discoveries of chemicals with strong anti-fungal properties in the leaves of an Elaeocarpus species in India. More research into the nature of New Zealand endemic Eleaocarpus spp. phytochemistry and its anti-fungal properties is warranted.

Biomass–fungi biocomposite materials are derived from sustainable sources and can biodegrade at the end of their service. They can be used to manufacture products that are traditionally made from petroleum-based plastics. There are potential applications for these products in the packaging, furniture, and construction industries. In the biomass–fungi biocomposite materials, the biomass particles (made from agricultural waste such as hemp hurd) act as the substrate, and a network of fungal hyphae grow through and bind the biomass particles together. Typically, molding-based methods are used to manufacture products using these biocomposite materials. Recently, the authors reported a novel extrusion-based 3D printing method using these biocomposite materials. This paper reports a follow-up investigation into the effects of mixing parameters (mixing time and mixing mode) on fungal growth in biomass–fungi mixtures prepared for 3D printing and the effects of printing parameters (printing speed and extrusion pressure) on fungal growth in printed samples. The fungal growth was quantified using the number of fungal colonies that grew from samples. The results show that, when mixing time increased from 15 to 120 s, there was a 52% increase in fungal growth. Changing from continuous to intermittent mixing mode resulted in an 11% increase in fungal growth. Compared to mixtures that were not subjected to printing, samples printed with a high printing speed and high extrusion pressure had a 14.6% reduction in fungal growth, while those with a low printing speed and low extrusion pressure resulted in a 16.5% reduction in fungal growth.

Background:Natural products are proved to play a good role as an alternative to synthetic chemicals in clinical conditions. Previous studies showed that Pelargonium graveolens has anti-inflammatory and antifungal activity against Candida albicans. The aim of this study was to evaluate the efficacy of essential oil of Pelargonium graveolens in the treatment of denture stomatitis.Materials and Methods:In this double-blind randomized clinical trial conducted in Isfahan (Iran), 80 (51 females and 29 males) eligible wearers of complete denture were included. According to the patients’ profiles number, they randomly divided to 2 groups of 40 patients’ case and 40 patients control treated with Pelargonium 1% gel or placebo, respectively. They were recommended to apply the gel twice daily for a 14-day course. All data were analyzed using SPSS® for windows (v.18). We have used the χ2 test for analyzing qualitative and Student t-test for quantitative data considering as P<0.05 as significant.Results:According to mycological data and clinical observation after treatment in the case group, 34% of patients had been improved completely, 56% partially and 10% had no improvement. In the control group, 5% of patients had complete recovery, 25% partial recovery, and 70% no improvement. A significant reduction in fungal growth was observed in case group rather than the control group (P value<0.0001).Conclusion:It seems that the application of a 1% Geranium oil topical gel formulation is more effective than placebo in the treatment of denture stomatitis.

Microfluidization was used to develop methyl cellulose (MC)/cellulose nanocrystal CNC based nanocomposite films containing a plant essential oil (EO) blend (oregano: thyme) emulsion. A three factorial experimental design was used to systematically optimize the microfluidization pressure based on size and antifungal activity of the prepared emulsion. Results showed that microfluidization of the film forming dispersions provide a novel approach for the development of high strength bionanocomposite films. Incorporation of 7.5% CNC into MC containing 0.50–0.75% EO and application of a pressure of 15 k psi (103 MPa) created a nanoemulsion with particle size ≤ 100 nm which exhibited significant antifungal activity in vitro against Aspergillus niger, A. flavus, A. parasiticus and P. chrysogenum. In situ tests with MC/CNC based bioactive films containing EO emulsion produced a 2 log reduction in fungal growth in infected rice during 8 weeks of storage at 28 °C. Methyl cellulose nanocomposite films containing EOs nanoemulsion showed a slow release (35%) of volatile component over 12 weeks of storage period. The addition of CNC as reinforcing filler improved the tensile strength of the MC based films by 30% and decreased water barrier and release properties by 9 and 25% respectively. In addition, combined treatment of bioactive films with an irradiation treatment at 750 Gy showed more pronounced antifungal and mechanical properties than treatment with the bioactive film or irradiation alone. These results show the potential for EO-loaded methyl cellulose-based films to prolong shelf life of food products.

Agricultural losses due to infections caused by phytopathogenic fungi are a threat to global food security. The use of chemical pesticides to combat these pathogens raises environmental concerns, making it necessary to seek more environmentally friendly alternatives. The aim of this work was to evaluate the antimicrobial activity of the cyclic lipopeptide surfactin, produced by Bacillus subtilis isolated from the intestine of honey bees. Specifically, the efficacy of surfactin against the phytopathogenic fungi Monilinia spp. and Aspergillus sp. was examined. First, in vitro assays were performed, showing that surfactin inhibited fungal growth by 88.39% for Monilinia polystroma, 67.40% for Monilinia fructigena, 49.56% for Monilinia laxa, and 33.02% for Aspergillus sp. Subsequent in vivo tests demonstrated its antifungal activity in apples and strawberries. In apples inoculated with M. laxa, surfactin application led to a 67.53% reduction in fungal growth and a 65.71% decrease in disease severity. Moreover, in strawberries, surfactin not only inhibited Aspergillus sp. growth but also extended the fruit’s shelf life, reducing disease severity by 80% after 15 days of storage at 4 °C. Additionally, treated strawberries retained higher firmness (up to 30% increase) and higher sugar content compared to untreated controls. These findings suggest that surfactin has potential applications in integrated pest and disease management as an alternative to agrochemicals, promoting more sustainable agricultural practices.

Control of Aspergillus flavus growth and aflatoxin production in transgenic maize kernels expressing a tachyplesin-derived synthetic peptide, AGM182

Antifungal activities of combined treatments of irradiation and essential oils (EOs) encapsulated chitosan nanocomposite films in in vitro and in situ conditions

Biological control to prevent fungal plant diseases offers an alternative approach to facilitate sustainable agriculture. Since the chitin in fungal cell walls is a target for biocontrol agents, chitinases are one of the important antifungal molecules. In this study, the aim was to investigate a new chitinase isolated from a fluvial soil bacterium and to show the antifungal activity of the characterized chitinase by comparing the three common methods. The bacterium with the highest chitinase activity was identified as Aeromonas sp. by 16S rRNA sequence analysis. Following the determination of the optimum enzyme production time, the enzyme was partially purified, and the physicochemical parameters of the enzyme were investigated. In the antifungal studies, direct Aeromonas sp. BHC02 cells or partially purified chitinase were used. As a result, in the first method in which the Aeromonas sp. BHC02 cells were spread on the surface of petri dishes, no zone formation was observed around the test fungi spotted on the surface. However, zone formation was observed in the methods in which the antifungal activity was investigated using the partially purified chitinase enzyme. For example, in the second method, the enzyme was spread on the surface of PDA, and zone formation was observed only around Penicillum species among the test fungi spotted on the surface. In the third method, in which the necessary time was given for the formation of mycelium of the test fungi, it was observed that the growth of Fusarium solani, Alternaria alternata and Botrytis cinerea was inhibited by the partially purified chitinase. This study concludes that the results of the antifungal activities depend on the method used and all fungal chitins cannot be degraded with one strain's chitinase. Depending on the variety of chitin, some fungi can be more resistant.

Antifungal efficacy of chitosan extracted from shrimp shell on strawberry (Fragaria × ananassa) postharvest spoilage fungi