Sucrose Medium Research Articles

Chemical composition of anti-microbially active fractions derived from extract of filamentous fungus Keratinophyton Lemmensii including three novel bioactive compounds

Screening for new bioactive microbial metabolites, we found a novel okaramine derivative, for which we propose the trivial name lemmokaramine, as well as two already known okaramine congeners – okaramine H and okaramine J - responsible for antimicrobial activity of the recently described microscopic filamentous fungus, Keratinophyton lemmensii BiMM-F76 (= CCF 6359). In addition, two novel substances, a new cyclohexyl denominated lemmensihexol and a new tetrahydroxypyrane denominated lemmensipyrane, were purified and characterized. The compounds were isolated from the culture extract of the fungus grown on modified yeast extract sucrose medium by means of flash chromatography followed by preparative HPLC. The chemical structures were elucidated by NMR and LC-MS. The new okaramine (lemmokaramine) exerted antimicrobial activity against Gram-positive and Gram-negative bacteria, yeasts and fungi and anticancer activity against different mammalian cell lines (Caco-2, HCT116, HT29, SW480, MCM G1, and MCM DLN). Furthermore, we found a significant antioxidant effect of lemmokaramine following H2O2 treatment indicated by activation of the Nrf2 pathway. This is the first report describing analysis and structural elucidation of bioactive metabolites for the onygenalean genus Keratinophyton.

Efficiency of Penicillium sp. and Aspergillus sp. for bioleaching lithium cobalt oxide from battery wastes in potato dextrose broth and sucrose medium

Lithium-ion batteries, a primary power source, generate electronic hazardous waste at the end of their lifespan, which is a richer source of highly concentrated metals such as cobalt and lithium than those in natural resources. The waste is a potential renewable resource for the extraction of metals. Bioleaching, a process utilizing microbial activity, was used in this study to investigate the cobalt and lithium leaching efficiency from battery wastes. Two fungal strains, Aspergillus sp. strain JMET 15 and Penicillium sp. strain JMET 24 were used with different organic carbon sources (sucrose medium and potato dextrose broth) at 1 % pulp density. The sucrose medium derived a higher acid quantity and leached higher concentration of cobalt and lithium than in potato dextrose broth. Leaching efficiency by JMET 24 was higher than JMET 15. Cobalt (32.57 % and 27.19 %) and lithium (65.07 % and 40.58 %) were bioleached by JMET 24 and JMET 15, respectively, after 30 d cultivation in the sucrose medium. Lower pulp density was conducted to achieved higher leaching efficiency by JMET24, cobalt (77.87 % and 74.5 %) and lithium (99.88 % and 78.4 %) were bioleached at 0.1 % and 0.5 % pulp density, respectively. Cobalt oxide (Co3O4) was the product of the one-step recovery (leaching and precipitation) process. Cobalt was transformed from lithium cobalt oxide to cobalt phosphate-oxalate by JMET 24 in the sucrose medium. Thus, the potential of bioleaching as an effective method for recovering valuable metals from lithium-ion battery waste is demonstrated, presenting a promising approach for both waste management and resource recovery.

Continental-scale insights into the sugarbeet diffusion juice microbiomes.

Bacterial contamination of raw diffusion juice poses unique challenges during the sugar extraction process. This study profiled bacterial communities by using full-length 16S rRNA amplicon sequencing and quantified the carbohydrate concentrations in raw diffusion juice samples received from sugar factory regions across the USA and Canada. Juice samples were collected at four time points during the 2021 and 2022 processing campaigns. Firmicutes was the dominant phylum from the raw diffusion juice samples collected during both campaigns and comprised 85.5% of total bacterial abundance. Lactic acid bacteria such as Leuconostoc and Lactobacillus were among the core genera which also dominated the bacterial community in raw diffusion juice. Positive correlations in the abundance of functionally and taxonomically related bacterial communities were identified. During the 2021 campaign, 44 bacterial genera were differentially abundant in raw diffusion juice extracted from sugarbeet roots in Periods 1 to 4. This number declined sixfold during the 2022 campaign to three genera. The concentration of raffinose in raw diffusion juice positively correlated to the relative abundance of Leuconostoc. Furthermore, an in vitro assay was performed to assess the growth dynamics of Leuconostoc mesenteroides in sucrose or raffinose-rich medium and observed the rapid consumption of both carbohydrates by this bacterium. This finding is important for deciphering microbial growth dynamics in raw diffusion juice that can be useful in minimizing sugar loss during the factory processing.IMPORTANCEFindings additionally provide baseline information that can be used to develop mitigation strategies that reduce losses due to microbial contamination of sucrose processing streams.

Acptp2,3 participates in the regulation of spore production, stress response, and pigments synthesis in Aspergillus cirstatus.

Aspergillus cristatus was a filamentous fungus that produced sexual spores under hypotonic stress and asexual spores under hypertonic stress. It could be useful for understanding filamentous fungi's sporulation mechanism. Previously, we conducted functional studies on Achog1, which regulated the hyperosmotic glycerol signaling (HOG) pathway and found that SI65_02513 was significantly downregulated in the transcriptomics data of ΔAchog1 knockout strain. This gene was located at multiple locations in the HOG pathway, indicating that it might play an important role in the HOG pathway of A. cristatus. Furthermore, the function of this gene had not been identified in Aspergillus fungi, necessitating further investigation. This gene's conserved domain study revealed that it has the same protein tyrosine phosphatases (PTPs) functional domain as Saccharomyces cerevisiae, hence SI65_02513 was named Acptp2,3. The function of this gene was mostly validated using gene knockout and gene complementation approaches. Knockout strains exhibited sexual and asexual development, as well as pigments synthesis. Morphological observations of the knockout strain were carried out under several stress conditions (osmotic stress, oxidative stress, Congo Red, and sodium dodecyl sulfate (SDS). Real-time fluorescence polymerase chain reaction (PCR) identified the expression of genes involved in sporulation, stress response, and pigments synthesis. The deletion of Acptp2,3 reduced sexual and asexual spore production by 4.4 and 4.6 times, demonstrating that Acptp2,3 positively regulated the sporulation of A. cristatus. The sensitivity tests to osmotic stress revealed that ΔAcptp2,3 strains did not respond to sorbitol-induced osmotic stress. However, ΔAcptp2.3 strains grew considerably slower than the wild type in high concentration sucrose medium. The ΔAcptp2,3 strains grew slower than the wild type on media containing hydrogen peroxide, Congo red, and SDS. These findings showed that Acptp2,3 favorably controlled osmotic stress, oxidative stress, and cell wall-damaging chemical stress in A. cristatus. Deleting Acptp2,3 resulted in a deeper colony color, demonstrating that Apctp2,3 regulated pigment synthesis in A. cistatus. The expression levels of numerous stress-and pigments-related genes matched the phenotypic data. According to our findings, Acptp2,3 played an important role in the regulation of sporulation, stress response, and pigments synthesis in A. cristatus. This was the first study on the function of PTPs in Aspergillus fungi.

Elimination of ineffective inorganic salt component in medium for indole‐3‐acetic acid synthesis by Serratia plymuthica UBCF_13 and its effect on the growth of chili seedlings

Indole‐3‐acetic acid (IAA) is an essential phytohormone that controls a variety of plant growth mechanisms. Bacteria can produce IAA to stimulate plant growth, with its production influenced by the culture conditions. Serratia plymuthica UBCF_13 is recognized as an IAA‐producing bacterium, exhibiting maximum IAA production in a yeast medium comprising yeast extract, sucrose, K2HPO4, MgSO4, NaCl, and CaCO3. However, prior studies optimizing individual inorganic salt components indicated minimal impact on IAA synthesis within this medium. This study aimed to eliminate the unnecessary inorganic salt components and the medium was then applied to investigate the IAA biosynthesis pathway and the plant growth‐promoting assay. The elimination assay consisted of yeast sucrose medium devoid of K2HPO4, MgSO4, NaCl, or CaCO3, and yeast sucrose medium containing only MgSO4 and CaCO3. Various indole compounds were then added to the revised medium composition to investigate the IAA biosynthesis pathway of UBCF_13 using high‐performance liquid chromatography (HPLC). Furthermore, the effect of UBCF_13 culture supernatant, cultivated in the new medium, on chili plant growth was evaluated. The highest IAA production (138.8 µg/mL) was observed in the yeast sucrose with CaCO3 and MgSO4 (elimination of K2HPO4 and NaCl). The presence of indole‐3‐acetamide (IAM) compound from the medium extracts, supplemented with multiple indole compounds, revealed that UBCF_13 may use the IAM pathway. The application of UBCF_13 supernatant enhanced the shoot, root length, fresh weight, and germination time of chili seeds by 37.7%, 49.3%, 204.3%, and 38.6%, respectively. This study demonstrated that eliminating K2HPO4 and NaCl provided a new culture medium composition conducive to IAA production by UBCF_13. Moreover, the UBCF_13 extract has the potential to promote plant growth.

The Development of an Improved Medium for the In Vitro Germination of Corylus avellana L. Pollen

The European hazelnut (Corylus avellana L.) is a self-incompatible, wind-pollinated species of significant economic-productive interest, mainly cultivated between the Mediterranean basin and the Black Sea. Hazelnut breeding programs and high cropping in commercial orchards are necessarily linked to the availability of fertile pollen with wide germinability and high viability. The objective was to develop an improved method to determine the germinability of pollen, comparing the results with those found in the literature. Pollen germinability was firstly evaluated on a wild-type accession using boric acid (H3BO3), calcium nitrate (Ca(NO3)2), magnesium sulfate (MgSO4), potassium nitrate (KNO3), casein hydrolysate and different concentrations of sugars, including sucrose (10, 15 and 25%) and two monosaccharides, glucose (15%) and fructose (15%). The optimal composition included 15% sucrose in a semi-solid medium composed of 1% animal gelatin, containing collagen. This formulation was then tested on three cultivars of commercial interest, evaluating the effect of different concentrations of sucrose. The comparison between different in vitro germination methods showed that the hanging drop technique in a semi-solid medium provides a statistically higher germination index compared to the liquid and solid/agarized techniques. This study proposes an easy-to-use medium for the in vitro germination of Corylus avellana L. pollen.

Investigation of a novel biofilm model close to the original oral microbiome

A more optimized culture medium used in vitro to mimic the bacterial composition of original oral flora as similar as possible remains difficult at present, and the goal of this study is to develop a novel oral biofilm medium to restore the original oral microbiome. Firstly, we conducted a systematic literature review by searching PubMed and summarized the current reported culture media in vitro. Seven culture media were found. We used mixed saliva as the origin of oral species to compare the effects of the above media in culturing oral multispecies biofilms. Results indicated that among the seven media brain heart infusion containing 1% sucrose (BHIs) medium, PG medium, artificial saliva (AS) medium, and SHI medium could obviously gain large oral biofilm in vitro. The nutrients contained in different culture media may be suitable for the growth of different oral bacteria; therefore, we optimized several novel media accordingly. Notably, results of crystal violet staining showed that the biofilm cultured in our modified artificial saliva (MAS) medium had the highest amount of biofilm biomass. 16S rRNA gene sequencing showed that the operational taxonomic units (OTUs) and Shannon index of biofilm cultured in MAS medium were also the highest among all the tested media. More importantly, the 16S rRNA gene sequencing analysis indicated that the biofilm cultured in MAS medium was closer to the original saliva species. Besides, biofilm cultured by MAS was denser and produced more exopolysaccharides. MAS supported stable biofilm formation on different substrata. In conclusion, this study demonstrated a novel MAS medium that could culture oral biofilm in vitro closer to the original oral microbiome, showing a good application prospect.Key points• We compare the effects of different media in culturing oral biofilms• A novel modified artificial saliva (MAS) medium was obtained in our study• The MAS medium could culture biofilm that was closer to oral microbiome

Sucrose supplements modulate the Pseudomonas chlororaphis-Arabidopsis thaliana interaction via decreasing the production of phenazines and enhancing the root auxin response

Management of the plant microbiome may help support food needs for the human population. Bacteria influence plants through enhancing nutrient uptake, metabolism, photosynthesis, biomass production and/or reinforcing immunity. However, information into how these microbes behave under different growth conditions is missing. In this work, we tested how carbon supplements modulate the interaction of Pseudomonas chlororaphis with Arabidopsis thaliana. P. chlororaphis streaks strongly repressed primary root growth, lateral root formation and ultimately, biomass production. Noteworthy, increasing sucrose availability into the media from 0 to 2.4% restored plant growth and promoted lateral root formation in bacterized seedlings. This effect could not be observed by supplementing sucrose to leaves only, indicating that the interaction was strongly modulated by bacterial access to sugar. Total phenazine content decreased in the bacteria grown in high (2.4%) sucrose medium, and conversely, the expression of phzH and pslA genes were diminished by sugar supply. Pyocyanin antagonized the promoting effects of sucrose in lateral root formation and biomass production in inoculated seedlings, indicating that this virulence factor accounts for growth repression during the plant-bacterial interaction. Defence reporter transgenes PR-1::GUS and LOX2::GUS were induced in leaves, while the expression of the auxin-inducible, synthetic reporter gene DR5::GUS was enhanced in the roots of bacterized seedlings at low and high sucrose treatments, which suggests that growth/defence trade-offs in plants are critically modulated by P. chlororaphis. Collectively, our data suggest that bacterial carbon nutrition controls the outcome of the relation with plants.

Selective production of two prebiotic extracellular polysaccharides from an oral probiotic lactic acid bacterium, Streptococcus salivarius SY511

Streptococcus salivarius is a lactic acid bacterium and an oral probiotic species. Growth of S. salivarius in a sucrose medium can lead to the production of exopolysaccharides (EPSs) that are potential prebiotics. However, no studies have yet examined use of this species for the selective production of high concentrations of EPSs. In this study, we isolated S. salivarius SY511 from infant feces and grew it in a sucrose medium to produce high levels of water-insoluble and water-soluble EPSs. NMR and monosaccharide analysis demonstrated that water-insoluble glucan and water-soluble levan were the two main EPSs. Batch fermentation in MRS-sucrose medium led to the efficient production of these two EPSs, and Tween 80 was a key factor that affected their differential production. In the fed-batch fermentation, 22.7 g/L of water-insoluble glucan was produced in the MRS-sucrose medium, while 24.9 g/L of levan was produced in the MRS-sucrose medium without Tween 80. Compared to S. salivarius M18, S. salivarius SY511 had higher or similar antimicrobial activity against major oral pathogens. Furthermore, the water-insoluble glucan and levan from S. salivarius SY511 had excellent prebiotic, anti-inflammatory, and antioxidant effects. Our study of S. salivarius SY511 identified a method for the selective production of two EPSs.

High frequency in vitro multiplication of polygonatum verticillatum (l.) All. From rhizome bud explants

This work aims to develop a rapid protocol for the in vitro establishment of Polygonatum verticillatum (L.) All., an astounding medicinal herb of Astavarga group of plants. Successful in vitro establishment was achieved utilizing rhizome bud segments of approx. 0.5 to 1.0 cm size as explants. Sterilized explants were cultured on MS medium containing graded concentration of different plant growth regulators used either singly or in various combinations. Maximum (85±10.0%) per cent shoot induction with maximum shoot length (6.50 ± 0.11cm) were recorded in TDZ (2.0 mg/l) + NAA(1.0 mg/l) + GA3 (2.0 mg/l) supplemented MS medium. NAA (1.0 mg/l) + Kn (0.5 mg/l) and IBA(1.0 mg/l) supplemented full strength MS medium with 3% sugar showed highest 70 ± 5.0% rooting response.½ MS+1.5 % sucrose medium augmented with IBA (1.0mg/l) showed the maximum average number of roots per explants (12.8 ± 1.07) with highest root length(6.12±0.27 cm). After hardening plantlets were transferred to pots in glasshouse produced healthy plants with 56% survival rate. Bangladesh J. Bot. 53(1): 203-208, 2024 (March)

Conformation Techniques for False Smut Pathogen (U. virens) on Rice through Cultural and Molecular Tools in Telangana

The study was conducted during period of January to April, 2022 at the Department of Plant Pathology and Institute of Biotechnology, Professor Jayashankar Telangana State Agricultural University, Rajendranagar, Hyderabad, Telangana state, India. The main objective of this study was to investigate cultural and morphological characteristics of U. virens isolates on potato sucrose medium (PSA) and their molecular confirmation collected from rice growing regions of Telangana during the kharif (rainy season), 2021. The isolates showed varying colony diameters and growth rates, with Uv3 reaching a maximum diameter of 77 mm and a growth rate of 2.85 mm, while Uv11 exhibited a minimum diameter of 40 mm with a growth rate of 1.48 mm. Notably, twenty two isolates showed diverse characteristics, including colony color, elevation, zonation, sectoring, and chlamydospore formation. Cluster analysis revealed the formation of five major groups, each group containing isolates with distinct features and PCR amplification with universal and species-specific primers yielded products of 700 bp and 380 bp, respectively. Phylogenetic tree analysis, indicated, Uv3 and Uv15 belonged to clade X and clade VII, respectively, both comprising Indian isolates. In contrast, Uv4 was grouped under clade II, which included both Chinese and Indian isolates. The proposed technique coupled with information of U. virens will immensely contribute to further studies on this fungus and false smut disease in India.

Cryopreservation of Limited Sperm Using A Combination of Sucrose and Taurine, Loaded on Two Different Devices, and Thawed at Two Different Temperatures.

Cryopreservation of sperm is essential for patients with low sperm counts and couples undergoing infertility treatment. The aim of this study was to compare the effects of Taurine (T) and Sucrose (S) in individual sperm cryopreservation utilizing cryotop and petri dish and thawing at 37 and 42°C. In this experimental study, 17 normospermic semen samples were processed using the "Swim-up" procedure and progressively motile sperm were then isolated from these samples using an inverted microscope. Sperm were added to droplets of "sucrose medium" with 25 mM Taurine antioxidant (S+T) and the commercial cryoprotectant "Sperm Freeze" (CPA), loaded on a petri dish and cryotop. After rapid freezing of the samples, they were thawed at two different temperatures (37°C and 42°C), and the sperm classical parameters, viability, and DNA fragmentation were assessed. Statistical analysis displayed a significant increase in total and progressive motility in individual sperm freezing on cryotop with CPA and thawing at 42°C (P<0.05). Other parameters did not show any differences between the CPA and S+T groups and two thawing temperatures in either of the cryopreservation methods. Although, both cryoprotectants (CPA and S+T) may preserve individual sperm effectively using cryotop, the CPA and thawing at 42°C showed a better effect on the motility percentage of the small number of sperm.

Transient Synaptic Enhancement Triggered by Exogenously Supplied Monocarboxylate in Drosophila Motoneuron Synapse

Current evidence suggests that glial cells provide C3 carbon sources to fuel neuronal activity; however, this notion has become challenged by biosensor studies carried out in acute brain slices or in vivo, showing that neuronal activity does not rely on the import of astrocyte-produced L-lactate. Rather, stimulated neurons become net lactate exporters, as it was also shown in Drosophila neurons, in which astrocyte-provided lactate returns as lipid droplets to be stored in glial cells. In this view, we investigate whether exogenously supplied monocarboxylates can support Drosophila motoneuron neurotransmitter release (NTR). By assessing the excitatory post-synaptic current (EPSC) amplitude under voltage-clamp as NTR indicative, we found that both pyruvate and L-lactate, as the only carbon sources in the synapses bathing-solution, cause a large transient NTR enhancement, which declines to reach a synaptic depression state, from which the synapses do not recover. The FM1-43 pre-synaptic loading ability, however, is maintained under monocarboxylate, suggesting that SV cycling should not contribute to the synaptic depression state. The NTR recovery was reached by supplementing the monocarboxylate medium with sucrose. However, monocarboxylate addition to sucrose medium does not enhance NTR, but it does when the disaccharide concentration becomes too reduced. Thus, when pyruvate concentrations become too reduced, exogenously supplied L-lactate could be converted to pyruvate and metabolized by the neural mitochondria, triggering the NTR enhancement. Significance statementThe question of whether monocarboxylic acids can fuel the Drosophila motoneuron NTR was challenged. Our findings show that exogenously supplied monocarboxylates trigger a large transient synaptic enhancement just under extreme glycolysis reduction but fail to maintain NTR under sustained synaptic demand, still at low frequency stimulation, driven to the synapses to a synaptic depression state. Glycolysis activation, by adding sucrose to the monocarboxylate bath solution, restores the motoneuron NTR ability, giving place to a hexoses role in SV recruitment. Moreover these results suggest exogenously supplied C3 carbon sources could have an additional role beyond providing energetic support for neural activity.

Multivariate Analysis Compares and Evaluates Heat Tolerance of Potato Germplasm.

High temperature is the most important environmental factor limiting potato (Solanum tuberosum L.) yield. The tuber yield has been used to evaluate the heat tolerance of some potato cultivars, but potato yield was closely correlated with the maturation period. Therefore, it is necessary to employ different parameters to comprehensively analyze and evaluate potato tolerance to heat stress. This study aimed to investigate physiologic changes during growth and development, and develop accurate heat tolerance evaluation methods of potato cultivars under heat stress. About 93 cultivars (including foreign elite lines, local landraces and cultivars) were screened using an in vitro tuber-inducing system (continuous darkness and 8% sucrose in the culture medium) under heat stress (30 °C) and normal (22 °C) conditions for 30 days. The tuber yield and number decreased significantly under heat stress compared to the control. A total of 42 cultivars were initially selected depending on tuber formation, after in vitro screening, further testing of selected cultivars was conducted in ex vitro conditions. The screened cultivars were further exposed to heat stress (35 °C/28 °C, day/night) for 60 days. Heat stress led to an increase in the plant height growth rate, fourth internode growth rate, and membrane damage, and due to heat-induced damage to chloroplasts, decrease in chlorophyll biosynthesis and photosynthetic efficiency. Three principal components were extracted by principal component analysis. Correlation and regression analysis showed that heat tolerance is positively correlated with the plant height growth rate, fourth internode growth rate, the content of chlorophyll b, photosynthetic rate, stomatal conductance, transpiration rate, tuber number, and tuber yield, and negatively correlated with the cell membrane injury level. The nine traits are accurate and representative indicators for evaluating potato tolerance to heat stress and could determine a relatively high mean forecast accuracy of 100.0% for the comprehensive evaluation value. Through cluster analysis and screening, cultivar FA, D73, and C132 had the highest heat comprehensive evaluation value, which could be further selected as heat-resistant varieties. This study provides insights into the different physiological mechanisms and accurate evaluation methods of potato cultivars under heat stress, which could be valuable for further research and breeding.

Production of Dextran by Leuconostoc mesenteroides Isolated from Home Made Fermented Foods

Dextran gum has important medicinal applications. The study was aimed to produce the dextran from Leuconostoc mesenteroides isolated from home made fermented foods. Two strains of Leuconostoc mesenteroides (LM-1 and LM-2) were isolated from chilli pickle and sauerkraut by enrichment culture technique. The isolates were subjected to dextran gum production using standard sucrose medium and modified medium made with sugar cane juice and &amp; liquid jaggery. Dextran gum produced by each isolate with different medium combinations was extracted and purified and subjected to conformity tests. The dextran produced by isolates was found to be viscous and soluble in water. The isolate LM1 showed highest yield of 3.50 g / 100ml with sugarcane juice medium. Sugarcane juice can be used as a source of sucrose which is economically affordable. However, more studies should be carried out to explore the process of dextran gum production

Comparative proteomics reveals the mechanism of cyclosporine production and mycelial growth in Tolypocladium inflatum affected by different carbon sources.

Cyclosporine A (CsA) is a secondary cyclopeptide metabolite produced by Tolypocladium inflatum that is widely used clinically as an immunosuppressant. CsA production and mycelial growth differed when T. inflatum was cultured in different carbon source media. During early fermentation, CsA was preferred to be produced in fructose medium, while the mycelium preferred to accumulate in sucrose medium. On the sixth day, the difference was most pronounced. In this study, high-throughput comparative proteomics methods were applied to analyze differences in protein expression of mycelial samples on day 6, revealing the proteins and mechanisms that positively regulate CsA production related to carbon metabolism. The differences included small molecule acid metabolism, lipid metabolism, organic catabolism, exocrine secretion, CsA substrate Bmt synthesis, and transcriptional regulation processes. The proteins involved in the regulation of mycelial growth related to carbon metabolism were also revealed and were associated with waste reoxidation processes or coenzyme metabolism, small molecule synthesis or metabolism, the stress response, genetic information or epigenetic changes, cell component assembly, cell wall integrity, membrane metabolism, vesicle transport, intramembrane localization, and the regulation of filamentous growth. This study provides a reliable reference for CsA production from high-efficiency fermentation. This study provides key information for obtaining more CsA high-yielding strains through metabolic engineering strategies.

Bacterial cellulose produced by Medusomyces gisevii on glucose and sucrose: biosynthesis and structural properties

In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) synthesized by Medusomyces gisevii have been studied. The culture medium was composed of different initial concentrations of glucose or sucrose dissolved in 0.4% extract of plain green tea. Parameters of the culture media (titratable acidity, substrate conversion degree etc.) were monitored daily for 20 days of cultivation. The BC pellicles produced on different carbon sources were characterized in terms of biomass yield, crystallinity and morphology by field emission scanning electron microscopy (FE-SEM), atomic force microscopy and X-ray diffraction. Our results showed that Medusomyces gisevii had higher BC yields in media with sugar concentrations close to 10 g L−1 after a 18–20 days incubation period. Glucose in general lead to a higher BC yield (173 g L−1) compared to sucrose (163.5 g L−1). The BC crystallinity degree and surface roughness were higher in the samples synthetized from sucrose. Obtained FE-SEM micrographs show that the BC pellicles synthesized in the sucrose media contained densely packed tangles of cellulose fibrils whereas the BC produced in the glucose media displayed rather linear geometry of the BC fibrils without noticeable aggregates.

The effect of plant growth regulators, carbon sources and gelling agent on the callus regeneration of Malaysian rice MR219 (Oryza sativa L.)

The development of a highly efficient tissue culture system for indica rice is crucial to speed up the implementation of gene editing in breeding programmes as well as to explore the roles of indica genes. However, because indica rice types are recalcitrant to in vitro response, there are only a few reports on the successful transformation process on indica rice due to recalcitrant response to in vitro response. The present study attempted to identify the effects of plant growth regulator (PGR), carbon sources and different concentrations of gelling agent on embryogenic callus induction and rice regeneration of Oryza sativa var MR219. The PGR used were 1 or 2 mg/L 6-benzylaminopurine (BAP) and 1-Naphthaleneacetic acid (NAA) and the carbon sources were 30 g/L sucrose and maltose. Three different gelling agent concentrations (3 mg/L, 6 mg/L or 9 mg/L) were evaluated. The highest frequency of friable callus induction (87%) was observed in callus induction media (CI) containing Murashige and Skoong media (MS) supplemented with 3 mg/L 2,4-dichlorophenoxy acetic acid (2,4-D) and 0.3 mg/L kinetin. Histological studies of the calli showed the presence of embryogenic calli with small intercellular spaces compared to non-embryogenic areas which developed on the hormone MS media. The highest regeneration frequency (50%) was achieved when friable calli were cultured on MS medium containing 3% sucrose, 1 mg/L BAP, and 1 mg/L NAA with 9% phytagel. The callus grown on sucrose media showed the highest number (66.13%) of albino plantlets, while the number of albino plantlets on maltose media was smaller (20%). In conclusion, this optimised mature embryo-derived callus of MR219 rice is responsive to regeneration and could be amenable to genetic transformation studies.

Using dielectrophoretic spectra to identify and separate viable yeast cells.

Immotile yeast cells were transiently moved in nonuniform sinusoidal electric fields using multiple pairs of micro-parallel cylindrical electrodes equipped with a sequential signal generator (SSG) to analyze cell viability at a clinical scale for the brewery/fermentation industry. Living yeast cells of Saccharomyces cerevisiae during the exponential-stationary phase, with a cell density of 1.15 × 105 cells mL-1 were suspended in sucrose medium. The conductivity (σs) was adjusted to 0.01 S m-1 with added KCl. Cells exposed in electric field strengths ranging from 32.89 to 40.98 kV m-1, exhibited positive dielectrophoresis (pDEP) with the lower critical frequencies (LCF) at 85.72 ± 3.59 kHz. The optimized value of LCF was shifted upwards to 780.00 ± 83.67 kHz when σswas increased to 0.10 S m-1. Dielectrophoretic and LCF spectra (translational speed of cells vs. electric field frequencies) of yeast suspensions during positive dielectrophoresis were analyzed in terms of the dielectric properties of the cell membrane and cytoplasm which reflect yeast cell viability and metabolic health status. The dielectrophoretic collection yield of cells using positive dielectrophoresis was reported on the monitor of sequential signal generator software to evaluate the number of living and dead cells through a real-time image processing analyzer. The spectra of both positive dielectrophoresis of the living and dead cells had distinguishable dielectric properties. The conductivity of the yeast cytoplasm (σc) of the dead cells was significantly less (≈ ≤ 0.05 S m-1) than that of the living yeast cells which typically had a cytoplasmic conductivity of ≈ 0.2 S m-1. This difference between viable and non-viable cells is sufficient for cell separation procedures. KEY POINTS: • Dielectrophoresis can be used to separate viable and non-viable yeast cells, • Cellular dielectric properties can be derived from the analysis of their dielectric spectra, • Cytoplasmic conductivity of viable cells is ≈ 0.2 S m-1 while that of non-viable cells ≈ ≤ 0.05 S m-1.

Is the mitochondrial ATP synthesis solely H+-driven, K+,H+ symport-driven or K+/H+ antiport-driven?

Some recent literature experimental data indicate that the mitochondrial ATP synthesis might be not solely H+-driven, but K+,H+ symport-driven membrane potential-dependent, considered as a further development of Mitchell's chemiosmotic theory, in contrast to the anti-Mitchell's hypothesis of K+/H+ antiport-driven mechanism. In this short communication, the attention was pointed to a possible influence of the ionic strength of the used KCl incubation medium, versus of only K+ ions, and of the Mg2+-induced mitochondrial aggregation in the sucrose medium on the reported rates of the mitochondrial respiration and ATP synthesis. These observations were based on the own author's experimental works published earlier.