Inoculum Concentration Research Articles

Effectiveness of Biological Assays as an Alternative Method to Determine the Potency of Antibiotics: A Review

In this review, chemical and biological assays performed in the pharmaceutical industry to determine the potency and bioactivity of antibiotics are discussed. Though commonly employed chemical methods can measure the potency of antibiotics, inefficiency to estimate the bioactivity is one of their major limitations. Due to their sensitivity and cost-effectiveness, common microbiological assays can serve as alternative methods. Several factors like doses of antibiotics, homogeneity of agar medium, inoculum concentration, chemical composition of agar media, size and solubility of samples or drug molecules, pH, relative humidity and exposure time can influence microbiological assays. Based on specific requirement and experimental targets, agar diffusion assays are designed focusing on their costs, errors, accuracy and simplicity. To avoid the misuse and overuse of antibiotics that leads to drug-resistance, parameters like zone of inhibition, minimum inhibitory concentration, minimum bactericidal concentration, mutation prevention concentration and critical concentration are also conversed in this study. Finally, microbiological and high-performance liquid chromatography methods were specifically compared for their sensitivity, accuracy and assessment of biological activity with minimal cost. Due to their advantages and disadvantages, parallel use of both bioassays and chemical methods are suggested to precisely determine the potency of antibiotics.

Bacterial cellulose from kombucha: Assessing inoculum age and concentration, and its conversion via enzymatic hydrolysis into cellobiose and glucose

Kombucha-type fermentation yields significant amounts of bacterial cellulose alongside the fermented beverage. This study evaluated the effects of inoculum age and concentration in kombucha-type fermentation using green acerola residue as an extract. The findings revealed that lower inoculum concentrations (2.5 and 5%) resulted in decreased bacterial cellulose (BC) yield. Conversely, increasing the inoculum concentration to 7.5% and 10% led to a 3.2-fold increase in BC yield. Inoculums aged just 3 days exhibited the lowest BC production, followed by older inoculums (9 and 12 days), suggesting reduced metabolic activity in the latter case. The optimal combination was found to be an inoculum age of 6 days and a concentration of 7.5%, resulting in a BC yield of up to 2.2 g/L using 70 g/L of carbon source. BC obtained from fermentation underwent enzymatic hydrolysis to yield cellobiose. Multi-stage hydrolysis - 1 stage (48 h), 2 (24 h, 24 h), 3 (12 h, 24 h, 24 h), and 4 (6 h, 6 h, 12 h, 24 h) - utilizing a methodology that anticipates the adsorption of endoglucanases onto the BC itself was employed to mitigate the inhibition of cellobiose on endoglucanases. The stages demonstrated an increase in cellobiose yield corresponding to the greater number of cycles, with 4 stages yielding 12.4% compared to 8.6% for hydrolysis conducted in a single stage. Despite the observed increase, the yield can be considered low and attributed to the loss of adsorbed enzymes between cycles due to the high crystallinity of the BC.

Fermentation of barley wort with Saccharomyces boulardii to generate a beverage with probiotic potential

Developing non-dairy functional beverages based on probiotics is a potential alternative for vegan consumers. It also becomes a big challenge since microorganisms can easily change chemical composition, acidity, color, and consumers’ acceptability. In this work, the probiotic yeast Saccharomyces boulardii was used to elaborate a fermented barley wort beverage. For the beverage formulations, the use of two flavors strawberry (SPB) and nutty (NPB) and two different inoculum concentrations (1 × 103 (SPB or NPB103) and 1 × 104 CFU/mL (SPB or NPB 104)) were considered. The fermentation was carried out at 37 °C under anaerobic conditions. The effect of the inoculum concentration was evaluated over reducing sugar consumption, the concentration of soluble solids, and pH. The best formulation was selected through a sensory evaluation. The profile of oligosaccharides and the resistance of the yeast to gastrointestinal conditions were determined only in the nutty flavor formulation (NPB 104). During the fermentation process, the content of oligosaccharides was increased compared to the unfermented wort, which improved the nutritional value. The analysis of resistance to simulated gastrointestinal conditions showed a decrease from 8.0 × 107 to 1.5 × 107 CFU/mL in the NPB 104 beverage. Barley wort is a potential medium to produce probiotic beverages with the yeast S. boulardii.

The Host Range of Fusarium proliferatum in Western Canada.

Fusarium proliferatum is associated with the root rot of many plant species, but knowledge of its impact on western Canadian field crops is limited. This study assessed the host range of this fungus and its effect on plant emergence, plant height, and shoot and root dry weights in repeated greenhouse experiments with wheat, barley, faba beans, peas, lentils, canola, lupine, and soybeans. Infection was confirmed via PCR, and principal component analysis determined the utility of different parameters in assessing host responses. All crops were at least partly susceptible, developing mild to severe disease at the seedling and adult stages, and showing significant reductions in growth. In general, the barley and wheat demonstrated higher tolerances to infection, followed by the faba bean and the pea. The soybean, canola, lupine, and lentil were most susceptible. The canola and the soybean were particularly vulnerable to F. proliferatum at the pre-emergence stage, while infection greatly reduced the lentil's biomass. Reductions in the barley's emergence and other growth parameters, however, occurred only under a high inoculum concentration. Variability in root rot severity among cultivars of the same crop indicated some diversity in host reactions within species. Nonetheless, the absence of fully-resistant crops may pose challenges in managing F. proliferatum in western Canadian cropping systems.

Degradation and inhibition kinetics of phenanthrene by Alcaligenes ammonioxydans, [VITRPS2] strain isolated from petroleum-contaminated soil

Phenanthrene, a common three-ring polyaromatic hydrocarbon [PAH], originates from sources like grilled meals, tobacco, crude oil, coal tar, and automobile exhaust. Recognized as a hazardous PAH, it is often targeted for bioremediation due to its sustainability and potential for full mineralization. In this study, we focus on biodegrading phenanthrene using the strain Alcaligenes ammonioxydans [VITRPS2], isolated from petroleum-contaminated soil. At 5 mg/ml, degradation occurred at a rate constant of 0.0181/day, with half-life values of 2.7 and 4.49 according to first and second-order kinetics, respectively. Employing a one-factor-at-a-time [OFAT] approach, we optimized biodegradation conditions within Luria–Bertani [LB] media. Under optimal conditions—pH 8.0, 8% inoculum concentration, and 37 °C incubation over seven days—the strain achieved maximal growth with phenanthrene as the sole carbon source. It exhibited a degradation efficiency of up to 72% for phenanthrene under these conditions. Gas chromatography-mass spectrometry [GC–MS] analysis revealed principal metabolites of the breakdown pathway, including salicylic acid, catechol, and various phthalic acid derivatives. This underscores the strain's potential for remediating environments polluted by PAH metabolites, showcasing its remarkable capability for complete phenanthrene degradation.Graphical abstract

Identification of Acinetobacter schindleri isolated from Chinese giant salamanders (Andrias davidianus)

At a particular aquaculture facility in Zhangjiajie in China, the Chinese giant salamander (Andrias davidianus) exhibited analogous clinical manifestations, culminating in sequential mortalities. This study used rigorous aseptic sampling methods to isolate bacteria from the affected liver of salamanders to determine the causative agent behind the decline in amphibians. A bacterial pathogen was isolated from diseased A. davidianus, and the strain was named DN-3. This isolate was subjected to bacterial identification, antibiotic susceptibility assays, reinfection experiments, and biochemical profiling. The isolated bacterial strain was definitively identified as Acinetobacter schindleri using 16S rRNA sequence analysis and biochemical identification. Antibiotic susceptibility testing revealed that this isolate was susceptible to neomycin, macrolides, doxycycline, piperacillin, nitrofurantoin, and carbenicillin. Subsequent reinfection assays, in which varying concentrations of the bacterial inoculum were administered to healthy salamanders, confirmed that the pathogen elicited varying degrees of morbidity or mortality within an eight-day observation period. The median lethal dose (LD50) of A. schindleri DN-3 for A. davidianus was calculated to be 6.25×104 CFU/mL. This result supports the significant pathogenicity of the strain for A. davidianus. The findings of this study provide empirical insights into the clinical management and epidemiological control of diseases affecting A. davidianus.

Comparative analysis of Streptococcus agalactiae serotypes Ia and II isolates from China and Pakistan in a murine model: A focus on pathogenesis and immune response

Bovine mastitis, caused by Streptococcus agalactiae (Group B Streptococcus; GBS), poses significant economic challenges to the global dairy industry. Mouse models serves as valuable tools for assessing GBS-induced infections as an alternative to large animals. This study aimed to investigate the LD50 dose, organ bacterial load, and quantification of peritoneal leukocyte populations for GBS serotypes Ia and II isolates from China and Pakistan. Additionally, we measured indicators such as lactoferrin, albumin, and myeloperoxidase (MPO) activity. Pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-2) and anti-inflammatory cytokines (IL-10 and TGF-β) in serum and tissue samples were evaluated using ELISA and qPCR, respectively. BALB/c mice (4 mice per group) received individual intraperitoneal injections of 100 μl containing specific bacterial inoculum concentrations (ranging from 105 to 109 CFU per mouse) of Chinese and Pakistani GBS isolates (serotypes Ia and II). Control groups received 100 μL of sterile PBS. Results revealed that the LD50 bacterial dose causing 50 % mortality in mice was 107 CFU. The highest bacterial load in all experimental groups was quantified in the peritoneum, followed by blood, mammary gland, liver, spleen, lungs, and brain. The most significant bacterial dissemination was observed in mice inoculated with Pakistani serotype Ia at 24 h, with a subsequent notable decline in bacterial counts at day 3. Notably, infection with Pakistani serotype Ia showed a trend of increased total leukocyte counts, significantly higher than Pakistani serotype II, Chinese Serotype Ia, and Chinese serotype II. A substantial influx of neutrophils and lymphocytes was observed in response to all tested serotypes, with Pakistani serotype Ia inducing a significantly higher influx compared to other groups (Pakistani serotype II, Chinese serotype Ia, and Chinese serotype II). Furthermore, TNF-α, IL-1β, IL-2, and IL-6 expressions were significantly increased in mice one day after infection with the Pakistani serotype Ia. Compared to mice infected with the Pakistani serotype II, Chinese Serotype Ia, and Chinese serotype II, those infected with the Pakistani serotype Ia isolate exhibited the highest production of IL-10 and TGF-β, along with significantly increased concentrations of lactoferrin, albumin, and MPO. These findings suggest that the persistence and severity of infection caused by the Pakistani serotype Ia may be linked to its ability to spread to deeper tissues. This study enhances our understanding of the clinical characteristics of bovine mastitis caused by S. agalactiae in China and Pakistan.

Efficiency of inoculation methods for the assessment of bacterial halo blight in coffee seedlings

AbstractBacterial halo blight (BHB), caused by Pseudomonas coronafaciens pv. garcae (Pcg), is one of the most significant diseases affecting coffee trees worldwide, resulting in considerable damage and notable losses within coffee production systems. Further research into the epidemiology and aetiology of BHB in coffee plants is essential for developing effective management strategies. Understanding the efficiency of each inoculation methodology in inducing symptoms is crucial for advancing this research. Therefore, this study aimed to assess the efficiency of seven Pcg inoculation methods using five concentrations to enhance the highest BHB intensity. The experimental design was a complete randomized block design in a factorial (7 × 5) variance analysis with four replications. The first three pairs of leaves of coffee seedlings of the cultivar Catuaí Vermelho IAC‐99 were inoculated and evaluated for the incidence and severity of BHB. The inoculation methods of Pcg by injury provided higher BHB AUDPCI and AUDPCS values. Among these, the inoculum injection and multi‐needle wounding at inoculum concentrations of 1.6 × 109 CFU mL−1 demonstrated higher disease intensity.

Unveiling the Cultivation of Nostoc sp. under Controlled Laboratory Conditions.

Cyanobacteria, photoautotrophic Gram-negative bacteria, play a crucial role in aquatic and terrestrial environments, contributing significantly to fundamental ecological processes and displaying potential for various biotechnological applications. It is, therefore, critical to identify viable strains for aquaculture and establish accurate culture parameters to ensure an extensive biomass supply for biotechnology purposes. This study aims to establish optimal laboratory batch culture conditions for Nostoc 136, sourced from Alga2O, Coimbra, Portugal. Preliminary investigations were conducted to identify the optimal culture parameters and to perform biomass analysis, including protein and pigment content. The highest growth was achieved with an initial inoculum concentration of 1 g.L-1, using modified BG11 supplemented with nitrogen, resulting in a Specific Growth Rate (SGR) of 0.232 ± 0.017 μ.day-1. When exposed to white, red, and blue LED light, the most favourable growth occurred under a combination of white and red LED light exhibiting an SGR of 0.142 ± 0.020 μ.day-1. The protein content was determined to be 10.80 ± 2.09%. Regarding the pigments, phycocyanin reached a concentration of 200.29 ± 30.07 µg.mL-1, phycoerythrin 148.29 ± 26.74 µg.mL-1, and allophycocyanin 10.69 ± 6.07 µg.mL-1. This study underscores the influence of light and nutrient supplementation on the growth of the Nostoc biomass.

Eugenia uniflora (pitanga) juice as a new alternative vehicle for Limosilactobacillus fermentum ATCC 23271: evaluation of antioxidant and anti-infective effects.

Probiotic-containing foods are among the most appreciated functional foods; however, probiotic-based dairy products cannot be consumed by people who are lactose intolerant, allergic to milk, or vegetarian or vegan individuals. Thus, new non-dairy matrices have been tested for probiotics delivery. This study evaluated the growth and viability of Limosilactobacillus fermentum ATCC 23271 and Lacticaseibacillus rhamnosus ATCC 9595 in Pitanga juice (Eugenia uniflora L.). The effects of the fermentation on the antioxidant and anti-infective properties of the juice were also analyzed. The E. uniflora juice allowed lactobacilli growth without supplementation, reaching rates around 8.4 Log CFU/mL and producing organic acids (pH values < 4) after 72h of fermentation. The strain remained viable after 35 days of refrigerated storage. Fermentation by these bacteria increases the antioxidant capacity of the juice. The central composite rotational design was employed to evaluate the effects of bacterial inoculum and pulp concentration on growth and organic acids production by L. fermentum ATCC 23271. The strain was viable and produced organic acids in all tested combinations. L. fermentum-fermented juice and its cell-free supernatant significantly increased the survival of Tenebrio molitor larvae infected by enteroaggregative Escherichia coli 042. The results obtained in this study provide more insights into the potential of Pitanga juice to develop a functional non-dairy probiotic beverage with antioxidant and anti-infective properties.

Tomato Brown Rugose Fruit Virus Is Transmissible through a Greenhouse Hydroponic System but May Be Inactivated by Cold Plasma Ozone Treatment

Tomato brown rugose fruit virus (ToBRFV) is an emerging tobamovirus infecting tomatoes and peppers, resulting in a pandemic in recent years. In addition to its abilities of being seed-borne, transmitted mechanically and overcoming current resistance, we speculated other factors may also contribute to such catastrophic effect on tomato production in a hydroponic greenhouse. The objective of this study was to evaluate whether ToBRFV can be transmissible through recirculating hydroponic systems and, more importantly, search for an effective approach to contain its spread. We not only detected ToBRFV in the runoff water samples collected from three greenhouses but also determined the virus’ infectivity through a bioassay. We then conducted a water treatment using cold plasma ozone to assess its efficacy in inactivating ToBRFV. The results showed that, with a high concentration of ToBRFV (inoculum in 1:100 dilution), a prolonged exposure (72 min) to two higher ozone concentrations (0.6 mg/L and 1.0 mg/L) achieved partial effects. With a medium virus concentration (inoculum in 1:1000 dilution), an exposure to ozone for 48 min was sufficient to completely suppress the virus’ infectivity. However, with a low virus concentration (inoculum in 1:10,000 dilution), the virus was completely inactivated even with just a short ozone exposure (24 min). Future work will need to confirm the efficacy of the ozone treatment against ToBRFV as well as its impact on tomato plants in a hydroponic greenhouse.

Immunity-related genes can serve as early diagnostic markers for infection in housefly rearing systems

Abstract Farming of houseflies, as well as of other insects, could become a sustainable alternative for producing high-protein animal feed. Although promising, this comes with particular challenges, including monitoring insect health in large-scale farming facilities. In this study, we tested if the expression patterns of immunity-related genes could serve as early diagnostic markers for disease and help prevent infection spread with detrimental effects. We introduced a commonly used bacterial entomopathogen, Bacillus thuringiensis, in the housefly larval substrate and monitored larval biomass changes, pupation, and gene expression of three immunity-related genes: PGRP, defensin, and cecropin. We performed the infection assay for two strains of different geographic origins at two temperatures and with two concentrations of the bacterial inoculum. We found that gene expression was faster in indicating differences between larvae grown in treated and untreated substrate compared to monitoring larval growth and pupation. Most strikingly, although there were no significant effects on larval biomass for 48 hours after the substrate inoculation, the effects on gene expression in some cases manifested already two hours post substrate inoculation. As the two housefly strains showed different response speeds in gene upregulation, there is a need for more frequent routine testing to define which response levels could be considered as an alarm. We conclude that monitoring immunity-related genes and microbial surveys of insect-rearing substrates can be used to diagnose infection and prevent its spread early in mass-rearing settings.

Correlations between the degree of infection by wild strain of Toxoplasma gondii in vitro and porcine hematological parameters

The apicomplexa Toxoplasma gondii is capable of actively proliferating in numerous types of nucleated cells, and therefore has a high potential for dissemination and resistance. Thus, the present work aimed to correlate the inoculum concentrations and amount of post-infection parasites with porcine hematological parameters (including biochemistry) through in vitro culture. Porcine blood was incubated with different concentrations of parasites (1.2 × 107, 6/3/1.5 × 106 cells/mL), then the concentrations of red blood cells (RBC) and their morphology, total and differential leukocytes, and free peptides were evaluated. In addition, eight different blood samples analyzed before inoculation, where subsequent multivariate analysis was applied to correlate different variables with trophozoite concentration. The results showed no significant variation (p < 0.05) in the relative levels of free peptides, or the relative percentage of RBC at all the parasite concentrations tested. However, the normalized percentages of leukocytes and neutrophils showed a significant reduction, while those of lymphocytes, eosinophils and monocytes showed the opposite behavior. Semi-automatic processing of images exhibited significant microcytosis and hypochromia. The multivariate analysis revealed a positive correlation between the amount number of protozoa (AP) and the variables: “Red cells” and “Neutrophils”, an indifference between the AP and the content of free peptides, and the concentration of monocytes in the samples; and a negative correlation for AP and the percentages of lymphocytes and eosinophils. Our results suggest that specific changes in hematological parameters may be associated with different degrees of parasitemia, demanding a thorough diagnostic process and adequate treatment.

Optimization and development of denser Chlorella vulgaris microalgae granules for easy harvesting via self-flocculation

Microalgae is widely utilized in water purification technology, biofuel production as well as in the synthesis of biopolymers. However, the separation of microalgae from its growth medium is the major issue that restricts the harvesting processes due to microalgae's lower density. In this study, the effect of environmental factors on microalgae granules development was investigated. Results from response surface methodology (RSM) revealed that maximum growth rate and biomass productivity were obtained at a photoperiod of 23.9 h, aeration rates of 2.4 L/min, inoculum concentration of 11 % and pH 6 respectively. The mixed liquor volatile suspended solids (MLVSS) value of the initial seed microalgae increased from 50 mg/L to 2978 mg/L after 70 days of cultivation. Microalgae productivity in this study is approximately 2 times faster than the standard suspension growing method. The microalgae settleability was significantly enhanced, as indicated by a major reduction in the sludge volume index (SVI30) from an initial value of >3000 to 58.51 mL/g, accompanied by an increase in settling velocity from virtually 0 to 19.2 cm/h and total harvesting time of 15 min. After 70 days of operation, smoothly settled, compact algal granules with largest sizes of 1.90 mm were obtained.

Characterization of malolactic fermentation by Lactiplantibacillus plantarum in red grape must

Malolactic fermentation (MLF) is a desirable biotransformation in red and some high-acidity white wines. This process involves the decarboxylation of l-malic acid into l-lactic acid by lactic acid bacteria (LAB). Among them, Oenococcus oeni and Lactiplantibacillus plantarum are the most common, being the last usually used as starter to perform MLF in wine. Compared with O. oeni, L. plantarum is less tolerant to wine conditions such as pH and ethanol; thus, it is preferable to inoculate it in must. The current literature has not yet addressed the impact of some parameters on the inoculation of this bacterium in grape must. Therefore, the aim of this work was to characterize the effect of the inoculum concentration, pH and ethanol tolerance, as well as the inoculation strategy, on the MLF performance of L. plantarum in grape must. We observed that a population < 108 CFU/mL could compromise MLF performance. Additionally, L. plantarum was able to survive at low pH values, such as 2.50, but in the presence of ethanol or a fermenting yeast, it could tolerate pH values in the range of 3.00–3.25. Finally, coinoculation or sequential inoculation with S. cerevisiae allows for the completion of MLF before the end of alcoholic fermentation.

High level of 1,3‐propanediol production from crude glycerol by Clostridium strain BOH3: critical roles of inoculum and substrate concentration

AbstractBACKGROUND1,3‐Propanediol (PDO) is a raw material/specialty chemical/additive in several industrial applications. A new wild‐type Clostridium strain BOH3 can utilize crude glycerol (CG) and produce PDO. This investigation reveals its potential for PDO production from CG.RESULTSInitially, inoculum of strain BOH3 was cultured from reinforced clostridial medium (RCM) with glucose (medium‐A), and modified‐RCM with glycerol (medium‐B). While fermenting 20 g L−1 glycerol, the cells cultivated from medium‐A produced 5.75 g L−1 PDO (as major product) with 3.10 g L−1 butanol (byproduct), whereas the cells cultivated from medium‐B produced 11.01 g L−1 PDO with 2.50 g L−1 butyric acid and 1.01 g L−1 acetic acid, with no butanol produced. To enhance PDO production from the batch‐process, various parameters including pure glycerol/CG concentration (80 g L−1), inoculum age (15 h) and size (12.50%v/v) of cells from medium‐B, initial medium‐pH (pH 6.4) and incubation temperature (39 °C) were studied; the optimal values obtained are given in their respective parenthesis. Under optimal conditions, PDO production was 42.58–47.15 g L−1 (0.65–0.79 mol‐PDO/mol‐glycerol) from CG‐based rich/mineral media. Furthermore, fed‐batch fermentation with 50–80 g L−1 initial CG‐concentration was tested to enhance the PDO production. Among these, 60 g L−1 initial CG‐concentration assisted strain BOH3 in utilizing a high level of CG (~174 g L−1); it supported a higher‐titer of PDO production (103.55–116.45 g L−1), with the highest yield (0.72–0.81 mol−PDO/mol−glycerol) ever reported.CONCLUSIONClostridium strain BOH3 shows the potential to support a high titer (&gt;116 g L−1) with the highest yield (&gt;0.80 mol mol−1) of PDO production from CG (a waste). It can be considered for industrial‐scale PDO production. © 2024 Society of Chemical Industry (SCI).

Optimization of robusta green coffee fermentation by Bifidobacterium bifidum and Lactobacillus plantarum using response surface methodology

In vitro fermented robusta coffee is fermented coffee beans using lactic acid bacteria (LAB) isolated from the stomachs of civets. In vitro fermented robusta coffee was obtained by optimizing three variables, namely inoculum concentration, use of microorganisms Bifidobacterium bifidum and Lactobacillus plantarum and in vitro fermentation time using response surface methodology (RSM). This study aimed to produce fermented robusta coffee in vitro with optimal cupping test results using three variables that affect fermentation. The results of the RSM showed that the optimum cupping test results were 72.62, inoculum concentrations of 5% (w/v), in vitro fermentation time of 8 hrs and the ratio of B. bifidum/L. plantarum at a ratio of 1:0.

Evaluation of Anaerobic Soil Disinfestation to Reduce Soilborne Diseases in Soilless and Soil-Based Substrates for Specialty Cut Flower Production.

Anaerobic soil disinfestation (ASD) is a nonchemical soil treatment where an easily decomposable carbon source is incorporated into soil, which is then irrigated to saturation and tarped to create anaerobic conditions, which prompts shifts in the soil microbiota from aerobes to anaerobes. ASD has been tested successfully for soilborne disease management in a variety of cropping systems but has not been sufficiently investigated in ornamentals. In this study, ASD was evaluated in soil-based and soilless substrates commonly used in specialty cut flower production using two model pathosystems: Rhizoctonia solani-Zinnia elegans and Phytophthora drechsleri-Gerbera jamesonii. Each substrate was mixed with pathogen-infested vermiculite and amended with either wheat bran, tomato pomace, or soybean meal as the carbon source. Amended substrates were incubated at 25°C for 4 weeks and used as growing substrates for the two crops mentioned above, which were monitored weekly for disease development for up to 5 weeks posttransplant. Additional experiments tested the effect of plant age and inoculum concentration in the substrate on ASD efficacy. Results showed that ASD has the potential to be deployed successfully for the control of Rhizoctonia stem rot in both substrates. Conversely, ASD was not effective at controlling Phytophthora crown rot on gerbera daisy in any of the experiments conducted in this study. More research is needed to understand the influence of carbon amendments, inoculum thresholds, and environmental conditions on ASD efficacy.

Use of Cranberry Bush (Viburnum opulus L.) Fruit Pomace as a Renewable Substrate for Biobutanol Production by Clostridium beijerinckii in the Presence of Sodium Dithionite

The present study aims to evaluate the use of cranberry bush fruit pomace (CBFP) (Viburnum opulus L.), which has recently become popular raw material, as a substrate in the presence of a reducing agent to increase biobutanol production by Clostridium beijerinckii DSMZ 6422. For this purpose, some factors were optimized, including the pretreatment, initial concentration of CBFP (5–20%), different types of reducing agents (ascorbic acid, L-cysteine, sodium dithionite and sodium sulfite), different concentrations of sodium dithionite (2.5–15 mM), inoculum concentration (5%, 10%, and 20%), and fermentation time (24–96 h). The maximum biobutanol, total ABE, biobutanol yield, and biobutanol productivity were 9.45 g/L, 12.08 g/L, 0.21 g/g, and 0.13 g/L/h in the medium containing enzymatically hydrolyzed 10% CBFP, 10 mM sodium dithionite, and 20% inoculum at the end of 72 h, respectively. These findings demonstrate that CBFP can be considered as a sustainable, economical, and viable substrate on biobutanol production for the first time in the literature.

Optimization of Bacterial Cellulose Production by Komagataeibacter rhaeticus K23

The use of bacterial cellulose (BC), having high purity, a high degree of crystallinity, water-holding capacity, tensile strength and adaptability on a broad scale is limited because of the low yield. In this study, the optimal conditions for bio-cellulose production by Komagataeibacter rhaeticus K23 were investigated. Optimal values for temperature, pH, inoculum concentration and incubation time were determined via Taguchi design. The maximum BC production, 9.1 ± 0.66 g·L−1 (dry weight), was obtained from 32 °C, pH 5.5, 8 log CFU·mL−1 and 14 days of incubation. The inoculum concentration was the most significant factor affecting BC yield. A value of 8 log CFU·mL−1 and 14 days of incubation led to significantly higher levels of BC yield than other concentrations (8.5, 9, 9.5, 10 and 10.5 log CFU·mL−1) (p &lt; 0.002) and days (15, 16, 17, 21 and 28) (p &lt; 0.001). The studied features, namely absorption peaks (Fourier transform infrared spectroscopy), pattern and the crystallinity index (X-ray diffraction analysis) of the BC obtained in this study were all in parallel with the characteristics of cellulose I. The study demonstrates that optimized parameters were effective in producing BC with high water-holding capacity, tensile strength, elongation and Young’s modulus (mechanical tests) by K. rhaeticus K23.