Inoculum Concentration Research Articles

A New Peptide Nucleic Acid Fluorescence In Situ Hybridization Probe for the Specific Detection of Salmonella Species in Food Matrices.

Salmonella spp. is among the most central etiological agents in foodborne bacterial disorders. To identify Salmonella spp., numerous new molecular techniques have been developed conversely to the traditional culture-based methods. In this work, a new peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) method was developed for the specific detection of Salmonella species, allowing a faster analysis compared with the traditional methods (ISO 6579-1: 2017). The method was optimized based on a novel PNA probe (SalPNA1692) combined with a blocker probe to detect Salmonella in food samples through an assessment of diverse-rich and selective enrichment broths. Our findings indicated that the best outcome was obtained using a 24-h pre-enrichment step in buffered peptone water, followed by RambaQuick broth selective enrichment for 16 h. For the enrichment step performance validation, fresh ground beef was artificially contaminated with two ranges of concentration of inoculum: a low level (0.2-2 colony-forming units [CFUs]/25 g) and a high level (2-10 CFUs/25 g). The new PNA-FISH method presented a specificity of 100% and a detection limit of 0.5 CFU/25 g of food sample, which confirms the great potential of applying PNA probes in food analysis.

Treatment of tannery effluent: An effective biological enhancement approach

AbstractThe water pollution due to tannery industries that contaminate river water and other spheres, is a side effect of industry expansion. The research focused on the biological removal of synthetic azo dyes by using biological treatment under aerobic conditions. Through morphological observation, biochemical test, and 16S rRNA sequence analysis the isolated bacteria were determined to be Aeromonas caviae, Enterobacter sichuanensis. Reduction of the organic content present in the tannery effluent and removal of the nutrients that cause pollution or inactivate potential pathogenic microorganisms or parasites. Optimized the azo dye degradation conditions at the temperature of 37°C, at pH 7 in 10% inoculum concentration at the time of 48th hour where novel organism capable of performing effective degradation. The metabolite of an aliquot mixture of the optimized condition was analyzed using Fourier Transform Infrared (FTIR) and the results confirmed the reduction of azo dyes. These results indicate that A. caviae and E. sichuanensis can be utilized as a solution for the remediation of tannery industrial effluent containing azo dyes.

Germinability of seed crops steeped at varying durations and inoculum concentrations of cultures of growth promoting rhizobacteria

Germinability of seed crops steeped at varying durations and inoculum concentrations of cultures of growth promoting rhizobacteria

Turning Waste into Wealth: Utilizing Trichoderma’s Solid-State Fermentation to Recycle Tea Residue for Tea Cutting Production

Trichoderma is a widely recognized plant-growth-promoting fungus that has been extensively utilized in various agricultural applications. However, research on the economic production of Trichoderma spores and their effects on tea cuttings must be further advanced. In this study, T. guizhouense NJAU 4742 (NJAU 4742) emerged as a growth-promoting strain for tea cuttings, and the spore-production conditions of NJAU 4742 attained through solid-state fermentation (SSF) using tea residues were optimized. In a pot experiment, nursery substrates containing different concentrations of NJAU 4742 spores were tested for their influence on tea cutting growth and the rhizosphere fungal community. The optimal conditions for spore yield were determined as a 7:3 (w/w) ratio of tea residue to rice bran, a material thickness of 3 cm, an inoculum concentration of 15% (v/w), and an incubation time of 4 days, resulting in a spore count of 1.8 × 109 CFU/g. Applying NJAU 4742 spore products significantly increased the biomass of tea cuttings and influenced the fungal community composition. Moreover, higher concentrations of NJAU 4742 spores yielded better growth performance, and applying nursery substrate with 1.0 × 107 CFU/mL spores was the most economically viable option. Notably, among the top ten fungal genera with the highest relative abundance, Trichoderma showed a positive correlation with the fresh weight of tea cuttings, while the others exhibited a negative correlation. Overall, utilizing tea residue for SSF to produce NJAU 4742 was a feasible approach, and the application of NJAU 4742 spores enhanced the growth of tea cuttings by increasing the relative abundance of Trichoderma.

Investigating the inoculum dynamics of Cladosporium on the surface of raspberry fruits and in the air.

Raspberry production is under threat from the emerging fungal pathogenic genus Cladosporium. We used amplicon-sequencing, coupled with qPCR, to investigate how fruit age, fruit location within a polytunnel, polytunnel location and sampling date affected the fruit epiphytic microbiome. Fruit age was the most important factor impacting the fungal microbiome, followed by sampling date and polytunnel location. In contrast, polytunnel location and fruit age were important factors impacting the bacterial microbiome composition, followed by the sampling date. The within-tunnel location had a small significant effect on the fungal microbiome and no effect on the bacterial microbiome. As fruit ripened, fungal diversity increased and the bacterial diversity decreased. Cladosporium was the most abundant fungus of the fruit epiphytic microbiome, accounting for nearly 44% of all fungal sequences. Rotorod air samplers were used to study how the concentration of airborne Cladosporium inoculum (quantified by qPCR) varied between location (inside and outside the polytunnel) and time (daytime vs. nighttime). Quantified Cladosporium DNA was significantly higher during the day than the night and inside the polytunnel than the outside. This study demonstrated the dynamic nature of epiphytic raspberry fruit microbiomes and airborne Cladosporium inoculum within polytunnels, which will impact disease risks on raspberry fruit.

Bacterial proximity effects on the transfer of antibiotic resistance genes within the alimentary tract of yellow mealworm larvae.

The arthropod intestinal tract and other anatomical parts naturally carry microorganisms. Some of which are pathogens, secrete toxins, or carry transferable antibiotic-resistance genes. The risks associated with the production and consumption of edible arthropods are dependent on indigenous microbes, as well as microbes introduced during the processes of rearing. This mass arthropod production puts individual arthropods in close proximity, which increases the possibility of their exposure to antibiotic-resistant bacteria carried by bacteria from fellow insects, industry workers, or rearing hardware and substrates. The purpose of this study was to determine if the alimentary tract of the yellow mealworm provided an environment permitting horizontal gene transfer between bacteria. The effect of the concentration of bacterial exposure was also assessed. Antibiotic resistance gene transfer between marker Salmonella Lignières (Enterobacterales: Enterobacteriaceae) and Escherichia coli (Migula) (Enterobacterales: Enterobacteriaceae) introduced into the larval gut demonstrated that the nutrient-rich environment of the yellow mealworm gut provided favorable conditions for the transfer of antibiotic resistance genes. Conjugation frequencies were similar across inoculum concentrations; however, transconjugant production correlated positively to increased exposure concentration. The lowest concentration of bacterial exposure required enrichment to detect and thus may have been approaching a threshold level for the 2 bacteria to colocate within the expanse of the larval gut. While many factors can affect this transfer, the simple factor of the proximity of donor and recipient bacteria, as defined by the concentration of bacteria within the volume of the insect gut, likely primarily contributed to the efficiency of antibiotic gene transfer.

Brewer’s spent grain as a self-sufficient feedstock for homofermentative production of optically pure L-lactic acid using Lactobacillus rhamnosus

Brewer’s spent grain (BSG), accounting for 85% of the total by-product from breweries, was used as a feedstock for L-lactic acid production in the present study. BSG was enzymatically hydrolysed and promoted to be a self-sufficient feedstock for L-lactic acid production by using it as a sole source of carbon, protein and minerals. Process parameters like glucose concentration (10–20 g/L), glucose-to-protein source ratio (1:1 – 5:1), source of protein and inoculum concentration (3 – 10% v/v) were selected to divert the carbon source and enhance L-lactic acid concentration, which would otherwise result in bacterial biomass production. Yeast extract and whey permeate resulted in high bacterial growth, whereas self-sustained protein (SSP) in BSG resulted in higher L-lactic acid production. Further, the glucose-to-protein source ratio was maintained at its lowest level for better glucose conversion to L-lactic acid. Glucose concentration strongly influenced L-lactic acid production. Therefore glucose concentration in the batch fermentation process was further increased from 60 to 120 g/L. A maximum L-lactic acid concentration of 114.4 g/L and productivity of 5.14 g/L·h was achieved with an initial glucose concentration of 120 g/L, and the rest of the process parameters such as glucose to protein source ratio of 1:1, inoculum concentration of 10% v/v and SSP in BSG were maintained at its optimum level. Finally, L-lactic acid in the fermentation broth was purified and analysed for its similarity with commercially available L-lactic acid using proton-NMR and FTIR spectroscopy. Thus, the present study valorised BSG by producing L-lactic acid under a biorefinery approach.

Effects of Soil Rhizobia Abundance on Interactions between a Vector, Pathogen, and Legume Plant Host.

Soil rhizobia promote nitrogen fixation in legume hosts, maximizing their tolerance to different biotic stressors, plant biomass, crop growth, and yield. While the presence of soil rhizobia is considered beneficial for plants, few studies have assessed whether variation in rhizobia abundance affects the tolerance of legumes to stressors. To address this, we assessed the effects of variable soil rhizobia inoculum concentrations on interactions between a legume host (Pisum sativum), a vector insect (Acyrthosiphon pisum), and a virus (Pea enation mosaic virus, PEMV). We showed that increased rhizobia abundance reduces the inhibitory effects of PEMV on the nodule formation and root growth in 2-week-old plants. However, these trends were reversed in 4-week-old plants. Rhizobia abundance did not affect shoot growth or virus prevalence in 2- or 4-week-old plants. Our results show that rhizobia abundance may indirectly affect legume tolerance to a virus, but effects varied based on plant age. To assess the mechanisms that mediated interactions between rhizobia, plants, aphids, and PEMV, we measured the relative expression of gene transcripts related to plant defense signaling. Rhizobia concentrations did not strongly affect the expression of defense genes associated with phytohormone signaling. Our study shows that an abundance of soil rhizobia may impact a plant's ability to tolerate stressors such as vector-borne pathogens, as well as aid in developing sustainable pest and pathogen management systems for legume crops. More broadly, understanding how variable rhizobia concentrations can optimize legume-rhizobia symbiosis may enhance the productivity of legume crops.

A Study on the Potentiality of Bioethanol Production from Selected Weed Species of the Asteraceae Family


 
 
 Increasing population growth, industrialization, and the harmful impacts of fossil fuel burning on the environment fascinated the researchers to find a low-cost, environmentally friendly alternative substitute. A potential substitute feedstock for the synthesis of second-generation bioethanol is the lignocellulosic biomass from invasive weedy plants. The aim of this study was to determine the potential of bioethanol production from two weedy plant species using physical, chemical, and physiochemical pretreatment methods, as well as to optimize the pretreatment and culture conditions to obtain a higher reducing sugar amount and ethanol yield. The collected invasive weedy plants, Chromolaena odorata and Tridax procumbens, were cleaned, then pretreated with different acids and bases (4% v/v) at 121oC for 15 min. Then the filtrate was incubated with Saccharomyces cerevisiae (baker‘s yeast) in the peptone yeast extract and nutrient medium (PYN) at room temperature, the pH was maintained at 5.0. T. procumbens plant substrate with the performic acid pretreatment agent produced a significant amount (0.2%) of ethanol, and further studies were conducted with the same substrate and the pretreatment agent. The conditions were optimized successively by changing one factor at a time while keeping the other variables constant. Several important hydrolysis factors were studied for the optimization, including performic acid concentration (0.2–5%), hydrolysis time (10–60 min), fermentation time (24–120 h), inoculum concentration (1.25–7.5 g/100 ml), and rotation speed (50–250 rpm). The maximum ethanol yield of 0.47% was observed at 0.6% performic acid concentration, 30 min of hydrolysis time, 48 h of fermentation time, 5 g/100 ml of inoculum concentration, and 100 rpm rotation speed with T. procumbens using S. cerevisiae.
 Keywords: Bioethanol, Lignocellulosic biomass, Acid hydrolysis, Saccharomyces cerevisiae
 
 

Optimized carotenoid production and antioxidant capacity of Gordonia hongkongensis.

The current emphasis within the cosmetic market on sustainable ingredients has heightened the exploration of new sources for natural, active components. Actinomycetota, recognized for producing pigments with bioactive potential, offer promising functional cosmetic ingredients. This study aimed to optimize pigment and antioxidant metabolite production from the Gordonia hongkongensis strain EUFUS-Z928 by implementing the Plackett-Burman experimental design and response surface methodology. Extracts derived from this strain exhibited no cytotoxic activity against human primary dermal fibroblast (HDFa, ATCC® PCS-201-012™, Primary Dermal Fibroblast; Normal, Human, Adult). Eight variables, including inoculum concentration, carbon and nitrogen source concentration, NaCl concentration, pH, incubation time, temperature, and stirring speed, were analyzed using the Plackett-Burman experimental design. Subsequently, factors significantly influencing pigment and antioxidant metabolite production, such as temperature, inoculum concentration, and agitation speed, were further optimized using response surface methodology and Box-Behnken design. The results demonstrated a substantial increase in absorbance (from 0.091 to 0.32), DPPH radical scavenging capacity (from 27.60% to 84.61%), and ABTS radical scavenging capacity (from 17.39% to 79.77%) compared to responses obtained in the isolation medium. The validation of the mathematical model accuracy exceeded 90% for all cases. Furthermore, liquid chromatography coupled with mass spectrometry (LC-MS) facilitated the identification of compounds potentially responsible for enhanced pigment production and antioxidant capacity in extracts derived from G. hongkongensis. Specifically, six carotenoids, red-orange pigments with inherent antioxidant capacity, were identified as the main enhanced compounds. This comprehensive approach effectively optimized the culture conditions and medium of a G. hongkongensis strain, resulting in enhanced carotenoid production and antioxidant capacity. Beyond identifying bioactive compounds and their potential cosmetic applications, this study offers insights into the broader industrial applicability of these extracts. It underscores the potential of G. hongkongensis and hints at the future utilization of other untapped sources of rare actinomycetes within the industry.

First report of Pectobacterium aroidearum causing soft rot on leaf mustard in China.

Leaf mustard (Brassica juncea [L.] Czern. et Coss.) is widely planted in China as an important leaf vegetable. In March 2022, water-soaked and mushy rot symptoms were observed on leaf mustard plants in the field of Zhaotong (27.85°N; 105.05°E), Yunnan, China. The incidence of symptomatic leaf mustard was approximately 10%. The isolation of the causal agent followed the method of Peng et al. (2023). Briefly, infected tissues from four diseased plants were mixed and teased apart, and homogenized by vortex shaking. The bacterial suspension was diluted and spread on nutrient agar (NA). About 10 single colonies exhibiting different colony morphologies were picked and purified separately by successive streaking. A pinprick method was used for pathogenicity tests with an inoculum concentration of 108 CFU/ml (Singh et al. 2013). Among 10 isolates, only strain YKX exhibited soft rot symptoms on detached mustard leaves. In addition, ten two-month-old leaf mustard plants grown in the greenhouse were used for in vivo pathogenicity tests. Briefly, sterilized pins were dipped in the bacterial suspension, and then leaf mustard petioles were pricked with these pins. After inoculation, each plant was kept in a plastic bag for 12 hours to maintain high humidity. As expected, strain YKX caused obvious rot symptoms on eight plants at 1-2 days post-inoculation while the control group including two plants treated with sterile water showed no symptoms. The colonies of strain YKX on NA were white, roughly circular, and convex. For a preliminary identification, total DNA was extracted and used as the template in PCR amplification of 16S rDNA with the universal PCR primer pair 27F/1492R (Weisburg et al. 1991). The quality-filtered DNA sequence (871 bp) showed 100% query coverage and 99.47% identity to the 16S rDNA sequences of type strain Pectobacterium aroidearum SCRI 109T (GenBank: NR_159926) found in the NCBI rRNA/ITS database. Whole-genome sequencing of strain YKX was then performed using the Illumina and Nanopore sequencing platforms by Tsingke Biotechnology Co., Ltd. (Beijing, China). A single contig (GenBank: CP129239) with a length of approximately 4.9 Mb was obtained by de novo hybrid assembly using Unicycler v0.5.0 (Wick et al. 2017). The quality of the genomic data was evaluated by BUSCO v5.4.7 (Manni et al. 2021) against the gammaproteobacteria_odb10 dataset. A BUSCO complete score of 99.5% indicated high assembly quality. The genome sequence of strain YKX was uploaded to the Type Strain Genome Server for a genome-based taxonomic analysis (Meier-Kolthoff et al. 2022). The distance-based phylogeny showed that strain YKX and P. aroidearum L6 (GenBank: CP065044) and P. aroidearum PC1 (GenBank: NC_012917) form a clade. When comparing strain YKX with L6 or PC1, the digital DNA-DNA hybridization value (83.5-83.8%) was above the species delineation threshold (70% for DDH), clearly indicating that strain YKX should be classified as P. aroidearum. Additionally, P. aroidearum was reisolated from inoculated leaves and identified based on morphological similarities and 16S rDNA sequencing, thus fulfilling Koch's postulates. It is worth noting that a previous study reported occurrences of soft rot disease on leaf mustard attributed to Rhizopus microsporus var. chinensis (Wang et al. 2020). To our knowledge, this is the first report of P. aroidearum causing soft rot on leaf mustard in China, which expands the known host range of this pathogen and benefits the control of this disease.

Optimization of culture conditions for xylanase production by mixed fungal fermentation: Effects on pretreated maize cobs

The use of microorganisms for xylanase production plays important role in the bioconversion of lignocelluloses and also required in huge amount for industrial level application. This necessitates the need to select potent microorganisms for xylanase production, followed by optimization of media components for enhanced production. The effects of altering cultural fermentation conditions on the xylanase production ability in maize cobs were investigated. A consortium of four fungi; Lenzites betulina, Trichoderma reesei, Lachnocladium specie and Aspergillus niger were used to carry out single and mixed solid-state fermentation on NaOH pretreated maize cobs. Optimization of fermentation factors were carried out from ten groups of individual and co-fermented fungal combinations. L. flavidum was found to be the most effective xylanase producer with optimal conditions at pH of 5.5, moisture 75%, inoculum concentration at 5-6 x 103 spores/ml, incubation period of 7-9 days and 1% peptone as the best nitrogen media supplement. Variation to different degrees in the degradation of the maize cobs were observed. A 10% decrease in cellulose was observed with co- cultures of T. reesei and A. niger and a 15% decrease in the hemicellulose fraction. The biotechnological potential of corn cobs has been enhanced by the screening and optimizing the culture conditions.

Effects of food wastes based on different components on digestibility and energy recovery in hydrogen and methane co-production

This study was conducted for four organic fractions (carbohydrates, proteins, cellulose, lipids) at an inoculum concentration of 30 % and a total solid (TS) of 8 % to investigate the effect of the main components of food waste on the performance of the two-stage anaerobic digestion. The results showed that the gas phase products were closely related to the composition of the substrate, with the carbohydrate and lipid groups showing the best hydrogen (154.91 ± 2.39mL/gVS) and methane (381.83 ± 12.691mL/gVS) production performance, respectively. However, the increased protein content predisposes the system to inhibition of gas production, which is mutually supported by changes in the activity of dehydrogenase and coenzyme F420. Butyric acid (53.19 %) dominated the liquid phase products in both stages, indicating that all four organic fractions were butyric acid-based fermentation and that the final soluble chemical oxygen demand degradation reached 72.97 %–82.86 %. The carbohydrate and cellulose groups achieved the best energy recovery performance, with conversion rates exceeding 65 %. The above results can provide a useful reference for the resource utilization of food waste.

Enhancing the Antioxidant Potential of Weissella confusa PP29 Probiotic Media through Incorporation of Hibiscus sabdariffa L. Anthocyanin Extract.

Lactic acid bacteria (LAB) produce important metabolites during fermentation processes, such as exopolysaccharides (EPS), which represent powerful natural antioxidants. On the other hand, H. sabdariffa L. anthocyanin extracts protect LAB and support their development. This study uncovers for the first time, the antioxidant profile of Weissella confusa PP29 probiotic media and focuses on elevating its impressive antioxidant attributes by synergistically integrating H. sabdariffa L. anthocyanin extract. The multifaceted potential of this innovative approach is explored and the results are remarkable, allowing us to understand the protective capacity of the fermented product on the intestinal mucosa. The total phenolic content was much lower at the end of the fermentation process compared to the initial amount, confirming their LAB processing. The DPPH radical scavenging and FRAP of the fermented products were higher compared to ascorbic acid and antioxidant extracts, while superoxide anion radical scavenging and lipid peroxidation inhibitory activity were comparable to that of ascorbic acid. The antioxidant properties of the fermented products were correlated with the initial inoculum and anthocyanin concentrations. All these properties were preserved for 6 months, demonstrating the promising efficacy of this enriched medium, underlining its potential as a complex functional food with enhanced health benefits.

Metarhizium spp. isolates effective against Queensland fruit fly juvenile life stages in soil.

Queensland fruit fly, Bactrocera tryoni, Froggatt (Diptera: Tephritidae) is Australia's primary fruit fly pest species. Integrated Pest Management (IPM) has been adopted to sustainably manage this polyphagous species with a reduced reliance on chemical pesticides. At present, control measures are aimed at the adult stages of the fly, with no IPM tools available to target larvae once they exit the fruit and pupate in the soil. The use of entomopathogenic fungi may provide a biologically-based control method for these soil-dwelling life stages. The effectiveness of fungal isolates of Metarhizium and Beauveria species were screened under laboratory conditions against Queensland fruit fly. In bioassays, 16 isolates were screened for pathogenicity following exposure of third-instar larvae to inoculum-treated vermiculite used as a pupation substrate. The best performing Metarhizium sp. isolate achieved an average percentage mortality of 93%, whereas the best performing Beauveria isolate was less efficient, with an average mortality of 36%. Susceptibility to infection during different development stages was investigated using selected fungal isolates, with the aim of assessing all soil-dwelling life stages from third-instar larvae to final pupal stages and emerging adults. Overall, the third larval instar was the most susceptible stage, with average mortalities between 51-98% depending on the isolate tested. Moreover, adult mortality was significantly higher when exposed to inoculum during pupal eclosion, with mortalities between 56-76% observed within the first nine days post-emergence. The effect of temperature and inoculum concentration on insect mortality were assessed independently with candidate isolates to determine the optimum temperature range for fungal biological control activity and the rate required for application in field conditions. Metarhizium spp. are highly efficacious at killing Queensland fruit fly and have potential for use as biopesticides to target soil-dwelling and other life stages of B. tryoni.

Drug resistance patterns and genotype associations of Trichomonas gallinae in meat pigeons (Columba livia): insights from Guangdong Province, China.

Avian trichomoniasis, caused by the protozoan parasite Trichomonas gallinae, is a prevalent and economically significant disease in pigeons. This study investigated the drug resistance of T. gallinae isolates in Guangdong Province, China. The results revealed that 25.3% (20/79) of the isolates were resistant to one or more of the four nitroimidazole drugs tested, namely, metronidazole, dimetridazole, secnidazole, and tinidazole. Secnidazole elicited the highest resistance rate (19.0%; 15/79), followed by tinidazole (17.7%; 14/79), metronidazole (17.7%; 14/79), and dimetridazole (13.9%; 11/79). An enormous majority of the resistant isolates (70.0%; 14/20) exhibited resistance to multiple drugs. Additionally, the resistance rate was significantly higher in isolates from birds aged < 30 days (53.3%; 8/15) than in those from older birds (23.1%; 12/52). Moreover, no drug resistance was detected in female pigeons. The genotype of the isolated strain was also associated with drug resistance. Specifically, 50.0% (15/30) of ITS-B genotypes exhibited resistance to drugs, while only 10.2% (5/49) of ITS-A genotypes demonstrated resistance. This study also found the growth characteristics of different Trichomonas isolates to be influenced by their genotypes and initial inoculum concentrations. These findings underscore the urgent need for effective measures to control and prevent drug-resistant T. gallinae infections in pigeons, thus ensuring the stable development of the pigeon industry.

Enhancing Bioethanol Production from &lt;em&gt;Azolla filiculoides&lt;/em&gt; through Optimization of Pretreatment and Culture Conditions with &lt;em&gt;Saccharomyces cerevisiae&lt;/em&gt;

Purpose: Increasing human population and extreme consumption of fossil fuels create a potential to generate alternative energy sources. Bioethanol is a renewable energy resource for fossil fuels and it can be produced from low-cost raw material. This study was aimed to convert the low-value freshwater flora into high-value bioethanol using Saccharomyces cerevisiae and to optimize the conditions for yield enhancement with the Azolla filiculoides substrate.Research Method: The freshwater flora was collected, cleaned, dried and then pre-treated with 1 M H2SO4 solution at 121 0C for 15 min. The flora with significantly higher yields of reducing sugar and alcohol was chosen for further research. Three pre-treatment techniques, including acid (1 M H2SO4), enzymatic (1% α-amylase), and a combination of both (1 M H2SO4 and 1% α-amylase) were applied to the selected substrate. The technique that resulted in a significantly higher reducing sugar and alcohol yield was chosen.Findings: The study revealed that Azolla filiculoides substrate produced significantly higher alcohol yield with Saccharomyces cerevisiae using combination of chemical and enzymatic pre-treatment technique. When fermentation was done at varying H2SO4 concentration (0.50-1.75 M), fermentation time (12-60 h), temperature (20-450C), rotation speed (50- 250 rpm) and inoculum concentration (25-150 g/L), and significantly higher alcohol yield (19 times than the non-optimized) was obtained after 36 h, at 40 0C and 0.75 M H2SO4 concentration with an inoculum concentration of 75 g/L at 200 rpm.Originality/ Value: The study concluded that Azolla filiculoides can be used as an efficient raw material for alcohol production.

Insecticidal and antioxidant potential of volatile compounds and nanoparticles from Tulbaghia violacea Harv. inoculated with endophytic fungus Beauveria bassiana (Bals.-Criv.) Vuill

This study aimed to investigate the effect of the entomopathogenic fungus Beauveria bassiana on the growth and ability of Tulbaghia violacea to synthesise nanoparticles and volatile compounds. Tulbaghia violacea was inoculated by drenching with different concentrations of B. bassiana conidial concentrations (0 mL−1, 1 × 106 mL−1, 1 × 107, and 1 × 108 conidia mL−1) and the colonization of plant tissue in the different fungal treatments was evaluated. A UV–VIS spectrometer (SPECTROstar nano) was used to determine the presence of nanoparticles while volatile constituents in the plants were analysed with chromatography-mass spectrometry. Polyphenols, alkaloids, flavonoids and antioxidant contents were determined using referenced methods. At least 57 % of plants were successfully colonized at the highest concentration (1 × 108 conidia mL−1). The results showed that treating B. bassiana with T. violacea had no significant effect (P>0.05) on the growth parameters (height, number of leaves, aerial part fresh weight, aerial part dry weight, root fresh weight, and root dry weight) of T. violacea after four weeks post-treatment. The aqueous extracts of T. violacea from both control and B. bassiana-treated plants successfully synthesized gold nanoparticles. Furthermore, the aqueous extracts of plants and gold nanoparticles from both fungus and control treatments were equally toxic to mealybug and induced high mortality. The Gas chromatography–mass spectrometry (GC–MS) results revealed that the number of compounds detected in plants subjected to the different concentrations of fungal inoculum and control did not vary significantly (P>0.05) in leaves and roots. The polyphenol contents in the leaves were not significantly different (P>0.05) among treatments. Similarly, the antioxidant activities were not significantly influenced (P>0.05) by fungal treatment on both leaves and roots. However, T. violacea extracts reduced aqueous gold to gold nanoparticles in both control and fungus-treated plants.

Inoculation and microelements: two important factors for enhanced conidiogenesis of Trichoderma asperellum in solid and liquid fermentation

The standardization of cultivation processes that allow high levels of conidia growth and formation is required to formulate Trichoderma products to combat fungal diseases in agronomically important crops. This study evaluated the effects of inoculation using different inoculum concentrations (1.0x105, 1.0x106, and 1.0x107 conidia mL-1) and inoculum volumes (10, 30, and 50 mL). Later, it evaluated the effect of adding microelements (CaCO3, KH2PO4, MgSO4*7H2O, and (NH4)2SO4) on the conidiogenesis of two strains of Trichoderma asperellum (GRB-HA01 and GRB-HA02) in solid-state and liquid fermentation processes. After 12 days of fermentation, the highest conidiogenesis values for Trichoderma asperellum GRB-HA01 (6.9x109±5.7x102 conidia g-1) and Trichoderma asperellum GRB-HA02 (1.3x109±1.4x102 conidia g-1) were achieved using an inoculum volume of 10 mL at a concentration of 1.0x07 conidia mL-1. Adding CaCO3 (1 g g-1), resulted in the highest conidia concentrations for Trichoderma asperellum GRB-HA01 (3.0x1011±2.5x102 conidia g-1) and Trichoderma asperellum GRB-HA02 (8.6x1010±1.1x101 conidia g-1), reducing fermentation times to 9 days. The conidiogenesis obtained with liquid fermentation was lower and affected Trichoderma asperellum GRB-HA01 (3.1x107±1.1x102 conidia g-1) and Trichoderma asperellum GRB-HA02 (3.1x109±2.8x102 conidia g-1). This study showed that inoculation and adding microelements were important factors in the conidiogenesis processes of Trichoderma asperellum GRB-HA01 and GRB-HA02. Additionally, it was evidenced that solid-state fermentations are more efficient than liquid fermentation processes.

A Model System to Evaluate the Potential of Floating Treatment Wetlands to Manage Phytophthora species in Recycled Irrigation Water

Highlights A floating treatment wetland (FTW) planted with Pontederia cordata reduced the flow-through of viable zoospores. Bacterial communities associated with FTWs that differed in remediation efficacy were characterized. FTWs have the potential to reduce plant pathogen load in water recycled for agricultural irrigation. Abstract. The increased incidence and severity of drought have reduced reliable access to freshwater irrigation sources for nursery and greenhouse plant producers. Many plant producers are now considering onsite remediation and reuse of water captured from irrigation return flow. However, potential contamination of recycled water with plant pathogens, primarily species of Phytophthora, is the primary concern preventing many growers from reusing their water. Floating treatment wetlands (FTWs) consist of plants established on a buoyant structure that floats on the surface of a water body with roots extended down into the water column. FTWs effectively remediate nutrients in agricultural runoff, but their potential to manage plant pathogens was previously unknown. Therefore, our objective was to investigate the potential efficacy of FTWs to manage species of Phytophthora in recycled irrigation water. Amplicon sequencing was performed to observe how the bacterial communities associated with the roots of plants in the various FTWs differed. The research was conducted using a controlled model system. Each model FTW consisted of a 3-m-long plastic trough that contained no plants, Agrostis alba plants, or Pontederia cordata plants. Nutrient-amended pond water continuously flowed through each trough at a set hydraulic retention time (HRT) of 1 h or 4 h. A standard inoculum concentration of Phytophthora nicotianae zoospores in aqueous suspension was added to influent water entering each trough, and zoospore activity in effluent water leaving each trough at predetermined time intervals was monitored with a baiting bioassay. Results from this study demonstrated that controlled model FTWs containing P. cordata plants effectively reduced the movement of viable P. nicotianae zoospores through a channel of nutrient-amended water at a target HRT of approximately 4 h. Movement of viable zoospores through the troughs was not reduced at the higher flow rate of 1 h HRT or for FTWs containing A. alba plants. Furthermore, the roots of A. alba and P. cordata had enriched bacterial communities that differed from one another. The mechanism by which FTWs containing P. cordata plants reduced zoospore activity was not determined; however, it may be due to interception of zoospores by plant roots, effects from plant root exudates, interactions with the root microbiome, or differences in water quality parameters. This is the first published study evaluating the potential efficacy of floating treatment wetlands to manage plant pathogens in irrigation water. Keywords: Ecological remediation, Horticulture, Microbial community analyses, Pathogens, Water reuse.