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Simple Summary: Food waste is increasing globally as living standards rise and the population grows. Effective management approaches are required to reduce environmental contamination. One growing alternative option is the bioconversion process, which treats organic waste using living organisms such as insects. Black soldier fly larvae (BSFL) can rapidly and effectively convert huge amounts of food waste into useful biomass, high in proteins and lipids, which can be utilized as animal feed or an alternative food source. Because microbiological safety and larval nutritional value are crucial, this study focused on how waste storage conditions affect these characteristics. The results showed that the waste handling method and its resulting quality significantly affect the microbial composition (load and diversity) and nutritional profile (protein, fat, and dry matter content) of BSFL. Waste storage in closed containers at refrigerator temperatures proved to be more suitable than open storage at room temperature, not only because of the improved microbial safety of the larvae but also because of a higher increase in the weight of the final larval biomass and accumulated protein content. This study suggests that proper waste handling methods can optimize the biodegradation process and improve BSFL quality and safety. This study assessed the bioconversion efficiency of Hermetia illucens larvae (BSFL) fed on food waste stored under different conditions, focusing on the nutritional and microbial quality of the resulting larval biomass. Food waste was prepared as a fresh diet (FD) or naturally contaminated and stored at 20–22 °C (OS-T, opened storage-tempered) or under refrigeration, at 5–8 °C (CS-C, closed storage-cooled). Refrigerated, closed storage (CS-C) led to the highest rates of waste reduction (91.0%) and bioconversion efficiency (30.2%), with larvae exhibiting the highest protein content (36.83%) compared to the FD (35.5%) and OS-T (34.71%) groups. Microbiome analysis revealed that the CS-C condition promoted beneficial yeasts like Pichia and Diutia, which correlated positively with improved protein content and microbial safety. In contrast, OS-T storage supported spoilage fungi (Mucor, Rhizopus) and elevated total aerobic counts (7.28 log CFU/g), indicating higher microbial risks. The observed trends in waste reduction and protein content most probably relate to differences in microbial profiles, as controlled cooling affected microbial dynamics, preserving substrate quality and supporting larval growth. These findings emphasize the importance of refrigerated, closed storage to optimize bioconversion, improve larval nutritional value, and minimize microbiological hazards. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the effect of Pseudomonas fluorescens (P) application on isofetamid (IS) dissipation; the number of specific genes of archaea, bacteria and ammonia-oxidizing bacteria (AOB); and the activity of β-Glucosidase, phosphomonoesterase, N-acetyl-glucosaminidase and arylsulfatase. It was observed that the IS concentration was lower in the P+IS than in IS throughout the entire study period, which indicates the potential of P. fluorescens to decompose isofetamid faster. IS+P application significantly influenced N-acetyl-glucosaminidase, arylsulfatase and phosphomonoesterase activity in soil compared to the control by approximately 29%, 72% and 6.5%, respectively. Moreover, it was observed that on day 21 in IS+P, the number of bacterial genes was significantly higher than in the control and IS and than on day 1, by 10% and 20%, respectively. On day 21, the number of archaea was significantly higher in all variants and ranged from 3.61 (control) to 6.88 log10 gene copies/g dm (IS+P). Correlation analysis showed a positive correlation between IS and TOC, while there was a negative correlation between IS and β-Glu and the number of archaea and AOB genes. The tested strain has the potential to be a biofertilizer and an agent in the bioremediation of contaminated soils. [ABSTRACT FROM AUTHOR]

Recent reports of P. olsonii causing postharvest rot of cherry tomatoes emphasize the need for effective strategies to prolong fruit shelf life. This study is the first to explore the use of essential oils (EOs), recognized for their antimicrobial properties, as a potential method to prevent postharvest losses from P. olsonii. Antifungal activity was tested for ten EOs at a concentration of 625 μL/L using the vapor diffusion method. Thyme, wild thyme, savory, oregano, and marjoram completely inhibited fungal growth over 14 days. Thyme EO, at a minimum inhibitory concentration (MIC) of 250 μL/L, fully inhibited all strains, while oregano, wild thyme, and savory were effective at 500 μL/L. Marjoram EO showed weaker activity. The lowest IC90 values, ranging from 35.72 to 162.72 μL/L, were estimated for thyme and oregano. In cherry tomatoes, oregano EO completely halted P. olsonii growth at 250 μL/L; thyme was effective for seven days; wild thyme and savory for two days. Thyme EO prevented P. olsonii spore germination at 500 μL/L for seven days, though germination occurred at half that concentration. The IC90 values varied between 256.2 and 138.7 μL/L depending on the strain. The vapor phase of EOs at 125 μL/L influenced the sensory characteristics of cherry tomatoes; however, for thyme and oregano, this effect was not negative due to their culinary association with tomato flavor. The selected EOs could be used to control and prevent postharvest fruit losses, but further research is needed to optimize their application. [ABSTRACT FROM AUTHOR]

Broad spectrum antimicrobial agents are urgently needed to fight frequently occurring multidrug-resistant pathogens. Myxobacteria have been regarded as “microbe factories” for active secondary metabolites, and therefore, this study was performed to isolate two bacteriolytic genera of myxobacteria, Myxococcus sp. and Corallococcus sp., from 10 soil/sand samples using two conventional methods followed by purification with the aim of determining the antimicrobial activity of methanol extracts against 11 test microorganisms (four Gram-positive, four Gram-negative, two yeasts and one fungus). Out of thirty-nine directly observed strains, 23 were purified and analyzed for antimicrobial activities. Based on the broth microdilution method, a total of 19 crude extracts showed antimicrobial activity. The range of inhibited wells was more important in the case of anti-Gram-positive-bacterial activity in comparison with the anti-Gram-negative-bacterial and antifungal activity. In light of the established degree and range of antimicrobial activity, two of the most active isolates (BNEM1 and SFEC2) were selected for further characterization. Morphological parameters and a sequence similarity search by BLAST revealed that they showed 99% sequence similarity to Myxococcus xanthus − BNEM1 (accession no. KX669224) and Corallococcus coralloides - SFEC2 (accession no. KX669225). As these isolates had antimicrobial activity, they could be considered for use in the development of antibiotics for pharmaceutical use.

The questionable safety of food spoiled by microorganisms is and should be the subject of attention and investigation. Pathogens such as Penicillium expansum are more difficult to control due to their resistance and ubiquity. Awareness of plant essential oils (EOs) as alternative natural preservatives is increasing because of their significant antimicrobial activity. The aim of this research work was therefore to contribute to this topic with new results. The antifungal activity of twelve EOs was tested in vitro against five strains of Penicillium expansum, using the vapour-phase diffusion method. Three EOs, from bergamot, star anise and rosaline, inhibited colony growth during two-week cultivation with a partial efficacy, all other EOs showed complete (100%) inhibitory activity at a concentration of 625 μL.L-1. These (EOs from clove, cinnamon, cinnamon bark, laurel, lemongrass, peppermint, Mitcham mint, spearmint, and lavender) were included in the second part of the trial, the aim of which was to determine their minimum inhibitory doses (MIDs). In the case of peppermint, Mitcham mint, spearmint and lavender EOs, some strains of P. expansum grew already at a concentration of 500 μL.L-1. Clove EO stopped the fungal growth of two strains at 250 μL.L-1. Laurel EO was 100% effective at MID 250 μL.L-1 throughout the cultivation period. EOs from lemongrass and cinnamon bark had similar efficacy on the strains. Both EOs were able to inhibit one strain at a MID of 125 μL.L-1, cinnamon bark EO inhibited the remaining strains at 250 μL.L-1, lemongrass EO inhibited three strains at 250 μL.L-1 and one at 500 μL.L-1. The lowest MID was recorded for cinnamon EO, which effectively inhibited two strains at 125 μL.L-1, two strains at 62.5 μL.L-1 and one strain even at 31.25 μL.L-1. The sensitivity of the strains used in this study varied according to the EOs used. [ABSTRACT FROM AUTHOR]

Essential oils (EOs) are a suitable alternative for extending the shelf life of foods. The aim of this research was to test the effect of fifteen EOs extracted from plants of the Lamiaceae family on five strains of Cladosporium cladosporioides. Cladosporium cladosporioides is frequently found on fruit and may be involved in fruit spoilage. The strains used in the study were isolated directly from lesions on berries. The growth of the fungi on the fruit was the reason for its rejection from sale. The antifungal activity of EOs against Cladosporium cladosporioides strains was determined by the microatmospheric method (625 μl EO/L air) during 14 days of cultivation. Thirteen EOs: thyme and red thyme (from Thymus vulgaris L.), mitcham mint (Mentha x piperita L. var. Mitcham), peppermint (Mentha x piperita L.), savory (Satureja hortensis L.), sage (Salvia officinalis L.), spearmint (Mentha spicata L. var. crispa), lavender (Lavandula angustifolia Mill.), marjoram (Origanum majorana L.), bergamot-mint (Mentha citrata Erh.), wild thyme (Thymus serpyllum L.), hyssop (Hyssopus officinalis L.), and oregano (Origanum vulgare L.) were shown to inhibit growth of all strains to 100%. Basil (Ocinum basilicum L.) and rosemary (Rosmarinus officinalis L.) EOs did not have a 100% inhibitory effect on all strains throughout the cultivation period. Subsequently, minimum inhibitory concentrations (MIDs) were determined using the microatmospheric method. LD90 and LD50 values were estimated by probit analysis. Based on the MID, LD90, and LD50 results, the essential oils can be divided into three groups. The first group (most effective): thyme, red thyme, spearmint, wild thyme, and oregano EO; the second group: peppermint, lavender, mitcham mint and savory EO; the third group: sage, marjoram, bergamot-mint and hyssop EO. The most effective EOs can be used to suppress the growth of Cladosporium cladosporioides in the vapour phase. [ABSTRACT FROM AUTHOR]

European corn borer (Ostrinia nubilalis) is an important maize pest which is treated mainly by synthetic pesticides with many negative effects for ecosystem and human health. Soil borne entomopathogenic fungi of species belonging to Beauveria genus may provide an alternative strategy for biological control of this pest. In this article, we report results of virulence testing of 46 soil isolates of Beauveria spp. against O. nubilalis in relation to isolates origin and haplotype. All strains were collected from soil using Galleria mellonella bait method. Conidia suspension with concentration 107 conidia in ml was used for virulence test against 4th instar larvae of O. nubilalis at temperature 25°C. After 14 days, mortality of larvae was in the range 34%–96%. Median lethal time LT50 was estimated to 5.5–21.3 days. Mortality was not in relation to habitat or any other environmental parameter of sites where isolates came from. Differences among species were insignificant. Isolates were divided into 8 genetic lineages and 14 haplotypes using sequencing of ITS and Bloc nuclear regions. None of the lineages showed higher mortality than others. Despite more or less virulent isolates being found in each lineage, the three most virulent isolates belonged to the same lineage Beauveria bassiana A3. The four most virulent isolates were compared to commercial isolate GHA to assess medium lethal concentration. LC50 were estimated in range 7.5 × 104 to 9.5 × 105. Three of the four isolates showed equal or greater efficiency than strain GHA. [ABSTRACT FROM AUTHOR]

The aim of the study was to assess microbial microbiome of 30 honey samples and compare potential differences between the samples from apiaries and commercial trade in Slovakia and foreign countries (Latvia, Switzerland, India, Japan and Tanzania) as well as to indicate their physico-chemical and basic microbiological quality. Study of each sample consisted of physico-chemical analysis (water content, pH, free acidity and electrical conductivity), basic microbiological analysis performed by dilution plating method (total plate count, sporulating aerobic microorganisms, bacteria from Enterobacteriaceae family, preliminary lactic acid bacteria and microscopic fungi) and metagenomic analysis for bacterial diversity evaluation. Seven samples did not meet with legislative limits of physico-chemical parameters. Average values of cultivable microbial groups ranged at level 1-2 log CFU.g-1, while bacteria from Enterobacteriaceae family were not detected in any samples. Sporulating microorganisms occurred most often, in 77% of samples and yeasts were proven in 60% of samples. Bacterial diversity, determined by metagenomic analysis, was varied. We distinguished 2 groups - group A and group B. Group A contained mainly fresh (produced in 2018) Slovak and Swiss honey and we found mainly genus Lactobacillus followed by genus Bombella in them. Group B contained mainly older Slovak honey (produced in 2017) and commercial foreign samples, in which production year is difficult to know. Group B samples were interesting because of human bacteria presence with genus Prevotella dominance. Redundancy analysis showed significant connection of the electric conductivity and microbial assemblage, that indicates important influence of botanical origin to microbial representation in honey. [ABSTRACT FROM AUTHOR]

Plant diseases caused by pathogenic fungi are a severe problem for agriculture, and some organic fertilizers have shown a suppressive capacity due to the antagonistic action of microbial communities inhabiting those substrates. The purpose of this work was to isolate and identify actinomycetes from soil, compost and vermicompost able to antagonize phytopathogens. In total, out of 352 actinomycetes successfully recovered on Pochon medium and of which were selected representative 22 mycelium forming isolates, which were subjected to morphological and genotypic characterization. Genetic characterization based on 16S rDNA fragment sequencing revealed that, all the actinomycete isolates belong to the genus Streptomyces. The antifungal activity of isolates was tested against eight phytopathogenic fungi, and they were most activated against Rhizoctonia solani, Alternaria tenuissima, Aspergillus niger and Penicillium expansum. Isolates 51VK13 (Streptomyces sampsonii) and 12VK13 (Streptomyces flavovariabilis) isolated from soil amended with vermicompost showed the greatest antagonistic activity. Their bioactive potential was also confirmed by presence of genes for nonribosomal peptide synthetase (NRPS) and polyketide synthase types I and II (PKS-I and PKS-II). It can, therefore, be concluded that soil amended with organic fertilizers such as compost, and in particular vermicompost, provides a lower incidence of phytopathogens, especially fungi. Isolated actinomycetes have also shown high potential for the production of bioactive compounds useful in the control of plant diseases. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of vermicompost application on microbial biomass carbon (MBC), dehydrogenase activity (DHA), and the functional diversity of microbial communities (BIOLOG assay using EcoPlates™) in the cultivation of maize. The greenhouse experiment included variants: control (no fertilizer), CAN (mineral fertilizer calcium ammonium nitrate 60 kg N ha-1), V20+CAN (vermicompost 20 t ha-1+mineral fertilizer 30 kg N ha-1), V40 (vermicompost 40 t ha-1) and V80 (vermicompost 80 t ha-1). Soil samples were analyzed at the start and end of the experiment (after 74 days). More pronounced influence of fertilization on biological parameters was found at the end than at the start of the experiment. MBC was statistically significantly higher in variants V40 (14.8%) and V80 (32.4%) than in the control. The application of CAN had a significantly negative effect, but the combination of V20+CAN positively influenced dehydrogenase activity. However, soil BIOLOG data indicated that the Shannon diversity index and evenness were significantly the lowest in the V20+CAN variant. The study suggests that vermicompost improves soil quality, and represents a suitable alternative to mineral fertilizers in the cultivation of maize. [ABSTRACT FROM AUTHOR]

The aim of this research was to determine the inhibitory effect of vapor phase of eight essential oils (EOs) on the growth of seven strains of Penicillium commune isolated from moldy milk products. Another objective was to determine the minimum inhibitory doses (in vitro and probit analyses) of EOs, which at concentration 625 μL.L-1 of air completely inhibited the growth of all strains. The antifungal activity was evaluated by the micro-atmosphere method. Thyme, red thyme, peppermint, mint, and savory completely inhibited the growth of strains during cultivation at 25 °C and 5 °C. Basil, rosemary, and sage EOs have different effects on the growth of P. commune strains. EOs that completely inhibit the growth of all strains were used to determine their minimum inhibitory doses (MIDs). The best results 62.5 μL.L-1 of air and 125 μL.L-1 of air 7th day at 25 °C of incubation showed red thyme EO. Similar results were also found in thyme EO, but the MID inhibiting the growth of the one strain was 250 μL.L-1 of air. MIDs of savory and peppermint were from 125 to 500 μL.L-1 of air. Mint EO had the highest MID (from 250 to 625 μL.L-1 of air). On the 14th day of incubation we found the same MIDs, respectively higher. It was found that EOs have different effects on individual strains of P. commune. According to probit analyses, the most effective tested EOs were red thyme and thyme, less effective peppermint and savory, and the least effective was mint EO. [ABSTRACT FROM AUTHOR]