Physiological-biochemical Characteristics Research Articles

Study of pathogenic activity and antibiotic resistance of cultured heterotrophic bacteria isolated from water and bottom sediments of the deep zone of the western part of the North Caspian sea

Commercial development of aquatic biological resources (ABR) of the Caspian Sea necessitates constant monitoring of the ABR habitat. Microbiota studies are of particular relevance, since bacterial communities largely determine the quality of the FBR habitat. The purpose of this work is to identify opportunistic and sanitary-indicative bacteria that have pathogenicity factors and antibiotic resistance and pose a danger for aquatic biological resources. The paper presents data on the taxonomic composition of saprotrophic bacterioplankton and bacteriobenthos in the waters of the Northern Caspian Sea in the period from 2013 to 2018. Water samples were taken annually in summer and autumn. The work used generally accepted methods for identifying bacteria by morphological and physiological-biochemical characteristics, as well as methods for determining antibiotic resistance and pathogenic activity. During the research period (2013–2018), more than 2000 isolates of saprotrophic bacteria belonging to 28 taxa were isolated from water samples and bottom sediments of the northern part of the Caspian Sea. The taxonomic composition of saprotrophic bacterioplankton and bacteriobenthos did not differ significantly in the number of taxa identified, but differed somewhat in the proportion of species, especially at the level of larger taxonomic groups. The study of bacterial virulence showed that the occurrence of various pathogenic properties in bacteria did not have a common direction in a number of years. Microorganisms isolated from water and soil of the northern part of the Caspian Sea had multiple antibiotic resistance to various groups of drugs. During the study period, high resistance of isolated bacteria (62–92% of isolated isolates) to benzylpenicillin and ampicillin was noted. In general, the presence of bacteria in the water and bottom sediments of the Northern Caspian Sea that have pathogenicity factors and multiple antibiotic resistance indirectly indicated the stress of the bacteriocenosis in the research area.

Physiological and Biochemical Effects of Exogenous Calcium on Camellia oleifera Abel under Drought Stress

High temperature and drought are the main factors restricting the increase in Camellia oleifera Abel production that can seriously harm its physiological and biochemical functions. This study aimed to explore the effect by which Ca2+ enhances the drought resistance of C. oleifera. Four-year-old potted plants of the ‘Xianglin 210’ variety were treated with four levels of CaCl2 solution (0, 10, 20, and 40 mmol/L) and subjected to natural drought stress. The drought levels were categorized as CS (non-drought), LD (light drought), MD (moderate drought), and SD (severe drought). The effects of drought stress on the growth and physiological-biochemical characteristics of C. oleifera were measured. Under drought stress, spraying CaCl2 solution on leaves could significantly increase the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), endogenous hormone indoleacetic acid (IAA) content, abscisic acid (ABA) content, and gibberellic acid (GA) content in organs and tissues; enhance the superoxide dismutase (SOD) activity; and decrease the concentration of intercellular carbon dioxide (Ci) and number of dehiscence fruits. Spraying 10 mmol/L CaCl2 effectively alleviates the damage of drought stress to tung oil trees. The study provides references for alleviating drought stress and increasing economic benefits in C. oleifera production.

The effect of Trichoderma harzianum agents on physiological-biochemical characteristics of cucumber and the control effect against Fusarium wilt

At the seedling and adult plant phases, pot experiments were carried out to enhance the physiological-biochemical characteristics of cucumber, guarantee its high yield, and ensure its cultivation of quality. Trichoderma harzianum conidia agents at 104, 105, 106, and 107 cfu g−1 were applied in accordance with the application of Fusarium oxysporum powder at concentrations of 104 cfu/g on the protective enzyme activity, physiological and biochemical indices, seedling quality, resilience to Fusarium wilt, quality, and yield traits. Fusarium oxysporum powder at 104 cfu g−1 was used to treat CK1, while Fusarium oxysporum powder and T. harzianum conidia agents were not used to treat CK2. The results show that different T. harzianum agents improved the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and peroxidase (POD) in cucumber seedlings, improved chlorophyll content, root activity, root-shoot ratio, and seedling strength index, and decreased malondialdehyde (MAD) content (P < 0.05). T3, a combination of 104 cfu g−1 Fusarium oxysporum powder and 106 cfu g−1 T. harzianum conidia agents, had the greatest promoting effect. The effects of different T. harzianum conidia agents and their application amounts on the control of cucumber Fusarium wilt were explored. T3 had the best promotion impact, and the control effect of cucumber Fusarium wilt at seedling stage and adult stage reached 83.98% and 70.08%, respectively. The quality index and yield formation of cucumber were also increased by several T. harzianum agents, with T3 having the strongest promotion effects. In comparison to CK1, the soluble sugar, Vc, soluble protein, and soluble solid contents of T3 cucumber fruit were 120.75%, 39.14%, 42.26%, and 11.64% higher (P < 0.05), respectively. In comparison to CK2, the soluble sugar, Vc, soluble protein, and soluble solid contents of T3 cucumber fruit were 66.06%, 24.28%, 36.15%, and 7.95% higher (P < 0.05), respectively. In comparison to CK1 and CK2, the yields of T3 cucumber were 50.19% and 35.86% higher, respectively. As a result, T. harzianum agents can enhance the physiological and biochemical traits of cucumber seedlings, raise the quality of cucumber seedlings, have a controlling impact on Fusarium wilt, and increase the yield and quality of cucumber fruit. The greatest effectiveness of T3 comes from its use. In this study, Trichoderma harzianum conidia agents demonstrated good impacts on cucumber yield formation and plant disease prevention, demonstrating their high potential as biocontrol agents.

Isolation and identification of protease-producing Bacillus amyloliquefaciens LX-6 and its application in the solid fermentation of soybean meal.

Soybean meal (SM) is considered an ideal substitute for fish meal; however, its application is mainly limited because of its antigen proteins, glycinin and β-conglycinin. To improve the value of SM in the aquaculture industry, we employed an aerobic bacterial strain (LX-6) with protease activity of 1,390.6 ± 12.5 U/mL. This strain was isolated from soil samples and identified as Bacillus amyloliquefaciens based on morphological and physiological biochemical characteristics and 16S rDNA gene sequence analyses. Subsequently, we quantified the extent of glycinin and β-conglycinin degradation and the total protein and water-soluble protein content after SM fermentation with B. amyloliquefaciens LX-6. At 24h of fermentation, the macromolecular antigen proteins of SM were almost completely degraded; the maximum degradation rates of glycinin and β-conglycinin reached 77.9% and 57.1%, respectively. Accordingly, not only did the concentration of water-soluble proteins increase from 5.74% to 44.45% after 48h of fermentation but so did the concentrations of total protein and amino acids compared to those of unfermented SM. Field emission scanning electron microscopy revealed that the LX-6 strain gradually disrupted the surface structure of SM during the fermentation process. In addition, B. amyloliquefaciens LX-6 exhibited broad-spectrum antagonistic activity and a wide pH tolerance, suggesting its application in SM fermentation for fish meal replacement.

Combined toxicity influence of polypropylene microplastics and di-2-ethylhexyl phthalate on physiological-biochemical characteristics of cucumber (Cucumis sativus L.)

Microplastics and di-2-ethylhexyl phthalate (DEHP) are prevalent and emerging pollutants in agro-ecosystem, raising concerns due to their widespread co-presence. Nevertheless, their combined toxicity on terrestrial plants remains largely unexplored. This study investigated the impact of polypropylene microplastics (MPs), DEHP, and their mixture on the physiological and biochemical characteristics of cucumber seedlings. The changes of membrane stability index (MSI), antioxidase activities, photosynthetic pigments and chlorophyll fluorescence in cucumber seedlings were assessed. The results demonstrated that MPs alone significantly inhibited MSI, photosynthetic pigments (Chl a, Chl b, and Chl a + b), Fm and qp of cucumber seedlings, and significantly promoted the carotene content and antioxidant enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) in cucumber seedlings. While DEHP alone significantly inhibited MSI and photosynthetic pigments of cucumber seedlings, and significantly promoted antioxidant enzyme activities in cucumber seedlings. Moreover, the combined toxicity of MPs and DEHP was found to be less pronounced than that of the single action of MPs and DEHP. The interaction between DEHP and MPs may contribute to the reduced toxicity. Abbott's modeling revealed that the combined toxicity systems were all antagonistic (RI < 1). Two-factor analysis and principal component analysis further confirmed that the treatment of MPs alone contributed the most to the toxicological effects of the physiological properties of cucumbers. In summary, this study highlighted the importance of understanding the combined effects of MPs and DEHP on plant physiology, providing insights for the development of effective treatments for emerging pollutants in agricultural ecosystems.

Changes in biochemical metabolites in manila clam after a temporary culture with high-quality microalgal feed mixed with the dinoflagellate species Karlodinium veneficum and K. zhouanum

Phytoplankton composition is an important factor affecting the growth and physiological biochemical characteristics of filter-feeding bivalves. With the increasing trend in dinoflagellate biomass and blooms in mariculture areas, how the physio-biochemical traits and seafood quality of the mariculture organism are affected by the dinoflagellates, especially those at nonfatal levels, is not well understood. Different densities of two Karlodinium species, namely K. veneficum (KV) and K. zhouanum (KZ), mixed with high quality microalgal food Isochrysis galbana was applied in feeding manila clam Ruditapes philippinarum in a 14-day temporary culture, to comparatively study how the critical biochemical metabolites such as glycogen, free amino acids (FAAs), fatty acids (FAs), volatile organic compounds (VOCs) in the clam were affected. The survival rate of the clam showed dinoflagellate density and species specificity. The high-density KV group inhibited survival to 32% lower than that of the pure I. galbana control, respectively, while KZ at low concentrations did not significantly affect the survival compared with the control. In the high-density KV group, the glycogen and FAA contents decreased (p < 0.05), indicating that energy and protein metabolism were significantly affected. Amount of carnosine (49.91 ± 14.64 to 84.74 ± 8.59 μg/g of muscle wet weight) was detected in all the dinoflagellate-mixed groups, while it was not present in the field samples or in the pure I. galbana control, showing that carnosine participated in the anti-stress activities when the clam was exposed to the dinoflagellates. The global composition of FAs did not significantly vary among the groups. However, contents of the endogenous C18 PUFA precursors linoleic acid and α-linolenic acid significantly decreased in the high-density KV group compared to all the other groups, indicating that high density of KV affected the metabolisms of fatty acids. From the results of the changed VOC composition, oxidation of fatty acids and degradation of free amino acids might occur in the clams exposed to dinoflagellates. The increased VOCs, such as aldehydes, and decreased 1-octen-3-ol probably produced a more fishy taste and reduced food flavor quality when the clam was exposed to the dinoflagellates. This present study demonstrated that the biochemical metabolism and seafood qulity of the clam were affected. However, KZ with moderate density in the feed seemed to be beneficial in aquaculture for increasing the content of carnosine, a high-valued substance with multiple bioactivities.

Growth and physiological–biochemical characteristics of cucumber (Cucumis sativus L.) in the presence of different microplastics

Growth and physiological–biochemical characteristics of cucumber (Cucumis sativus L.) in the presence of different microplastics

The characteristics of actinomyces strptomyces griseorubiginosus 83 – the effective biosorbent of silver

The bacteria bound about the same amount of silver at the time of inoculation and when added after 24 hours Fourier transform infrared spectroscopy (FT-IR) and measurements of the ζ- potential showed that several groups, mainly carboxy groups are involved in the binding and biotransformation of silver cations. Also, volatile organic compounds profiling for L. lactis, demonstrated the presence of many compounds in the free space of bacteria, which were typical products of bacterial metabolism. Finally, it can be stated that the combination of various instrumental methods used has opened up new possibilities for the interpretation of physicochemical phenomena occurring at the interface between bacteria-bacteria and bacteria-metals- bacteria. The ability of the biomass of cultures of various taxonomic groups to sorb metals is used both for purification of wastewater from metals and in the additional separation of valuable and environmentally significant metals from various wastes. In this work 48 strains of actinomycetes were isolated from various samples of desert soils of Uzbekistan under agricultural crops. As a result of screening, a strain of Streptomyces sp. 83, efficiently absorbs silver from solutions. The morphological-cultural and physiological-biochemical characteristics of the selected

Nitrogen fertilization in bamboo forest accelerates the shoot growth and alters the lignification process in shoots

As one of the key nutrients, nitrogen is a major driving force for plant growth and development, and ultimately contributes to biomass improvement. However, little is known about the common genetic basis of bamboo growth with nitrogen fertilization in forests. Here, the physiological-biochemical characteristics showed that nitrogen fertilization in moso bamboo forest obviously affected the activities of multiple enzymes in bamboo shoots, which led to changes in metabolite content. The lignin content was significantly inhibited in bamboo shoots during the early stages of fast growth (from 1.0 m to 4.0 m), while the content was subsequently promoted at the late stage, which resulted in a lignin content similar to that of the control observed in 8.0 m shoots. By integrating the physiological-biochemical and transcriptome data, we generated a global map of changes in the transcriptomic dynamics during fast growth, which showed that upregulated DEGs in 1.0 m and 4.0 m shoots were significantly enriched in growth- and development-related GO terms, while those DEGs in 8.0 m shoots were enriched in lignin biosynthesis-related GO terms. Using weighted correlation network analysis (WGCNA), two complex regulatory networks were constructed: two key structural genes (KSGs) and 118 transcription factors (TFs) involved in nitrogen metabolism and 17 KSGs and 102 TFs involved in lignin biosynthesis. Furthermore, the regulatory mechanism of KSGs targeted by TFs was validated by yeast one-hybrid assays. Overall, nitrogen fertilization differentially affected moso bamboo shoots at different fast growth stages through the expression of genes involved in multiple metabolic pathways, indicating that moso bamboo has plasticity to environmental factors. These results provide a better understanding of the changing patterns in moso bamboo shoots and lay a foundation for the genetic improvement and sustainable management of bamboo forests via nitrogen fertilization. • Nitrogen fertilization promotes the growth of moso bamboo shoots. • Nitrogen fertilization changes the shoot lignification process through the gene expression in shoots. • Moso bamboo shoots prefer to use ammonium nitrogen at the late stage of fast growth.

Characterization and genomic analysis of a bensulfuron methyl-degrading endophytic bacterium Proteus sp. CD3 isolated from barnyard grass (Echinochloa crus-galli).

Bensulfuron methyl (BSM) is a widely used sulfonylurea herbicide in agriculture. However, the large-scale BSM application causes severe environmental problems. Biodegradation is an important way to remove BSM residue. In this study, an endophytic bacterium strain CD3, newly isolated from barnyard grass (Echinochloa crus-galli), could effectively degrade BSM in mineral salt medium. The strain CD3 was identified as Proteus sp. based on the phenotypic features, physiological biochemical characteristics, and 16S rRNA gene sequence. The suitable conditions for BSM degradation by this strain were 20-40°C, pH 6-8, the initial concertation of 12.5-200 mg L-1 with 10 g L-1 glucose as additional carbon source. The endophyte was capable of degrading above 98% BSM within 7 d under the optimal degrading conditions. Furthermore, strain CD3 could also effectively degrade other sulfonylurea herbicides including nicosulfuron, halosulfuron methyl, pyrazosulfuron, and ethoxysulfuron. Extracellular enzyme played a critical role on the BSM degradation by strain CD3. Two degrading metabolites were detected and identified by using liquid chromatography-mass spectrometry (LC-MS). The biochemical degradation pathways of BSM by this endophyte were proposed. The genomic analysis of strain CD3 revealed the presence of putative hydrolase or esterase genes involved in BSM degradation, suggesting that a novel degradation enzyme for BSM was present in this BSM-degrading Proteus sp. CD3. The results of this research suggested that strain CD3 may have potential for using in the bioremediation of BSM-contaminated environment.

Low-temperature adaptation and preservation revealed by changes in physiological-biochemical characteristics and proteome expression patterns in post-harvest Hami melon during cold storage.

The proteome and its time-dependent effects reveal the importance of stress response (including expression regulation of heat-shock proteins) and fatty acid metabolism in cold adaptation and preservation of Hami melon. To better understand the molecular mechanism of how Hami melons respond to low-temperature stress, this study investigated the relevant physiological characteristics, catalytic antibody activity, and quantitative proteomics of Hami melon (Jiashi muskmelon) during low-temperature storage. Jiashi muskmelon was stored inside two refrigerators set at 21°C (control group) and 3°C, respectively, for 24days. Low-temperature storage led to a significantly reduced decay rate, weight loss rate, and loss of relative conductivity. It also maintained fruit firmness, inhibited the production rate of malondialdehyde and H2O2, and induced over-expression of antioxidant enzyme and ATPase. A total of 1064 differentially expressed proteins (DEPs) were identified during low-temperature storage. Stimulation response was the main process in response to low-temperature. To further verify the proteome data, we selected four heat-shock proteins (HSP) displaying relatively high expression levels. Real-time fluorescence PCR results confirmed that HmHSP90 I, HmHSP90 II, HmHSP70, and HmsHSP were significantly up-regulated upon low-temperature induction. These proteins may protect the Hami melon from physiological and cellular damage due to the low-temperature stress by acting alone or synergistically. Additionally, the main enrichment term of the fatty acid metabolism-related DEPs was fatty acid beta oxidation at 21°C in contrast to fatty acid biosynthesis processes at 3°C. It is speculated that Hami melon enhances low-temperature adaptability by slowing down the oxidative degradation of fatty acids and synthesizing new fatty acids at low temperatures. This study provides new insights into the mechanism of low-temperature adaptation and preservation in post-harvest Hami melon during cold storage.

Agrobiological evaluation of collection samples of soy vegetable in the Forest Steppe of Ukraine

Purpose. Agrobiological assessment of soybean varieties Glycine max var. Shirofumi on a complex of economically valuable traits for introduction in the conditions of the Forest-Steppe of Ukraine. Selection of promising breeding forms based on morpho-biological and physiological-biochemical characteristics. Methods. Field, laboratory, statistical, computatio­nal and analytical. The studies were carried out in the conditions of the educational and production department of Uman National University of Horticulture during 2020–2021, using collection varieties of different ecological and geographical origin (Ukraine, Belarus, Sweden, Japan and Russia). The cultivars were assessed according to the following parameters: plant height, leaf area, net productivity of photosynthesis and indices of individual productivity (weight of beans per plant, number of seeds in a bean, etc.), productivity of green beans and biologically mature seeds and, accordingly, quality indicators of production (dry matter, sugar and protein content). The counts were carried out in the phase of the technical ripeness of the beans. Results. The variability of the “plant height” trait of the studied varieties had an average variation – the coefficient of variation was 22%. The results showed that the standard cultivar ‘Romatnyka’ and the collection cultivars ‘Karikachi’ and ‘Astra’ belong to the semi-determinant type of growth (97–109 cm), cultivar ‘Fiskeby V’, ‘L 380-2-13’, ‘Fiskeby V-E5’, ‘SibNIISOKh 6’, ‘Sac’, ‘Vesta’ belong to the determinant type of growth. According to the number of seeds in the pod, the studied varieties were clearly divided into two groups: with two-seeded beans (varieties ‘Karikachi’, ‘Astra’, ‘L 380-2-13’) and three-seeded beans [varieties ‘Romatnyka’ (standard), ‘Fiskeby V’, ‘Vesta’, ‘SibNIISOX 6’, ‘Sac’, ‘Fiskeby V-E5’]. The maximum yield of edamame beans was produced by varieties ‘L 380-2-13’ (17.3 t/ha), ‘Vesta’ (18.8 t/ha), ‘Sac’ (19.6 t/ha), ‘Fiskeby V’ (21.4 t/ha), ‘Fiskeby V-E5’ (22.4 t/ha). A significant differentiation of soybean varieties in the biochemical composition of immature beans was revealed. The dry matter content was 22.70–31.70%. The share of protein in edamame green beans was 28.2–38.6%, in biologically mature seeds its share increased to 36.1–42.8%. Among soluble sugars, the highest concentration was noted for sucrose – 7.70–9.38 mg/100 g in dry seeds, what in average amounted to 81.6–86.2% of all sugars. The presented results provide a comprehensive assessment of breeding work on soybean varieties with a low content of oligosaccharides. Conclusions. Evaluation of collection varieties of vegetable soybeans by the variability of morphological traits and productivity made it possible to distinguish ‘Sac’ variety by a complex of valuable traits for creation of new varieties of vegetable soybeans adapted to the conditions of the Forest-Steppe of Ukraine.

Physiological-biochemical responses of wheat to blending controlled-release potassium chloride and soluble potassium chloride

The crop yields and potassium use efficiency (KUE) could be enhanced by controlled-release potassium chloride (CRK), yet the effects of blending 50 % CRK and 50 % soluble potassium chloride (BBF), on crop physiological-biochemical characteristics were not reported. We carried out a five-year field experiment during 2014–2019 with five K fertilization treatments in a completely randomized block design using wheat (Triticum aestivum. L.) as a testing crop. The results showed that: compared with K1 (full-dose of soluble potassium chloride (KCl)) treatment, the SPAD value and photosynthetic rate of BBF1 (full-dose of BBF) treatment were increased by 7.3–12.2 % and 36.5–59.0 %, respectively, at jointing and grain-filling stages; the auxin and abscisic acid in leaves and roots of BBF1 treatment proliferated by 14.0 %, 27.2 % and 19.5 %, 25.0 %, respectively, at jointing stage; the root total volume and surface area of BBF1 treatment were sharply risen by 80.2 % and 38.8 %, respectively, at jointing stage. The yield and net profit of BBF1 treatment increased by 5.0–19.7 % and 7.2–28.7 %, respectively. With K fertilization rate reduced by 30 %, BBF2 treatment produced almost the same yield as with the 100 % rate of monotypic soluble KCl treatment. This study demonstrated that combining CRK and soluble KCl improved the root physiological characteristics and endogenous hormones of wheat and consequently increased wheat yield.

Low-molecular components of colostrum as a regulator of the organism redox-system and biological antidote

The protein composition in the diapason of molecular masses from 4800 to 9500 Dа has been studied in colostrum, taken from different cows, and manifested the expressed biological activity. For this aim, an influence of low-molecular components of colostrum on some physiological parameters (change of body mass and temperature) at intoxication of animals (Wistar rats) by blue stone has been studied. An influence of colostrum low-molecular components on parameters of the organism redox-system (content of hyperperoxides of lipids and activity of glutathione peroxidase) in the blood serum of animals has been studied. For determining integral characteristics of colostrum components, electric conductivity of skim colostrum and one of colostrum with low-molecular proteins (less than 10 000 Dа), taken from different cows, were used. The aim of this work is to study interconnections of an influence of colostrum low-molecular proteins on models of organism intoxication by cooper ions.&#x0D; It is demonstrated, that the colostrum composition includes 25–35 different proteins with a molecular mass from 4800 to 9500 Dа. The number and ratio between protein fractions depend on individual physiological-biochemical characteristics of producers. It has been revealed, that there is no direct dependence between the protein content in a measuring cell (2 mg/ml, 4 mg/ml and 10 mg/ml) with skim colostrum and electric conductivity change, and this dependence is different for skim colostrum, taken from different cows. Individual differences are manifested both at electric conductivity change and by the content of colostrum low-molecular proteins in a measuring cell. It is demonstrated, that colostrum low-molecular components can eliminate the toxic effect of blue stone on the organism, which mechanisms are connected with a balance shift in the system “prooxidants↔antioxidants” towards antioxidants. The electric conductivity of colostrum components may be used as an express-method for evaluating biologically active substances of colostrum

ШТАММ PSEUDOMONAS SP. DD4 ДЛЯ ДЕСТРУКЦИИ ГАЛОГЕНСОДЕРЖАЩИХ ПАВ И ГЕРБИЦИДОВ

The paper describes the properties of a strain isolated from a natural population of soil microorganisms exposed to petrochemical production, capable of destroying fluorinated surfactants and some halogenated herbicides. In the model system, the growth dynamics of the DD4 bacterial strain was studied and it was shown that the culture actively accumulates biomass when using a fluorine-containing foaming agent such as a foaming agent and active substances of the herbicides Octapon, Chistalan, and Florax as a source of carbon and energy. Based on the data obtained, the DD4 bacterial strain can be used in remediation technologies for territories with a disturbed ecological status, formed when using fluoride-containing fire extinguishing agents and unregulated use of chemical plant protection products. According to the results of cultural-morphological, physiological-biochemical characteristics and the sequence of the 16S RNA DD4 gene, the strain was identified as a representative of the genus Pseudomonas.

Effect of High CO2 Treatment and MA Packaging on Sensory Quality and Physiological-Biochemical Characteristics of Green Asparagus (Asparagus officinalis L.) during Postharvest Storage

Green asparagus is vulnerable to thrips that carry microorganisms and cause deterioration in quality. The effects of 60% CO2 treatment, which is used to kill thrips, combined with perforated (P) or modified atmosphere (MA) packages during cold storage, on the sensory quality and physiological–biochemical characteristics of asparagus were investigated. MA packaging yielded an asparagus shelf-life five days longer than P packaging. The 60% CO2 treatment for 48 h at 4 °C packaged with MA film (CO2-48 h-4 °C-MA) showed a lower number of aerobic bacteria, yeast, and mold. Yellowing of asparagus was retarded, as shown by higher hue angle and chlorophyll content and lower chlorophyllase activity. Also, CO2-48 h-4 °C-MA treatment inhibited the reduction of soluble solids content in asparagus. Likewise, all high CO2 treatments showed lower electrolyte leakage (EL), with CO2-48 h-4 °C-MA demonstrating the minimum EL. The effectiveness of high CO2 on maintaining sensory qualities was observed, with a score higher than 3.0. In conclusion, CO2-48 h-4 °C-MA treatment during cold storage was effective for maintaining post-harvest sensory qualities and physiological–biological traits of asparagus, and provided strong inhibition of microflora growth during the storage period.

Diversity of Cultivable Microbes From Soil of the Fildes Peninsula, Antarctica, and Their Potential Application.

To explore the diversity and application potential of Antarctic microorganisms, 1208 strains bacteria and fungi were isolated from 5 samples collected from the Fildes Peninsula during China’s 27th and 31st Antarctic expeditions. By using 16S and ITS sequence similarity alignment, 83 strains bacteria belonging to 20 genera and 30 strains fungi belonging to 7 genera were identified. Among them, 1 strains bacteria and 6 strains fungi showed low sequence similarity to the database, suggesting that they might be novel species. Physiological-biochemical characteristics showed that the identified bacteria could utilize many kinds of carbohydrates and that the identified fungi could produce several kinds of extracellular enzymes. The fungal strain MS-19, identified as Aspergillus sydowii, possesses the potential to produce antifungal activity agents based on an activity-guided approach. Further isolation yielded four polyketones: versicone A (1), versicone B (2), 4-methyl-5,6-dihydro-2H-pyran-2-one (3), and (R)-(+)-sydowic acid (4). It should be noted that 1 displayed strong activity against Candida albicans, with an MIC value of 3.91 μg/mL.

Biological control of poplar anthracnose caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc.

Poplar anthracnose is one of the most serious diseases caused by the fungal pathogen Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Biocontrol is an efficient green way for the disease control, and numerous researches have focused on exploring the potential biocontrol bacteria strains against C. gloeosporioides. In this study, antifungal activities against C. gloeosporioides of 108 rhizosphere soil isolates from healthy polar plants were investigated in vitro by the dual culture assay. The results suggested that strain ZSH-1 showed the highest level of antifungal activity, as it inhibited C. gloeosporioides at a distance of 10.00 mm. Based on the morphological, physiological-biochemical characteristics, and phylogeny analysis, strain ZSH-1 was identified as Bacillus subtilis. The sterile culture filtrate, crude protein, and crude lipopeptide extracts from the culture filtrate, and volatile compound(s) of ZSH-1 displayed a strong antagonism towards 7 fungal phytopathogens (C. gloeosporioides, Fusarium oxysporum, Alternaria tenuissima, Cytospora chrysosperma, Botryosphaeria dothidea, Mucor sp., and Absidia sp.), with inhibition rates ranging from 44.0 to 89.1%, 26.7 to 85.4%, 11.6 to 89.7%, and 7.8 to 63.2%, respectively. Moreover, ZSH-1 exhibited cell wall-degrading traits by producing 3 lytic enzymes (cellulose, β-1,3-glucanase, and protease). Finally, the greenhouse studies also revealed that strain ZSH-1 had a 47.6% (12 days) efficacy in controlling poplar anthracnose when compared with the control. In concluding, obtained results demonstrate the potential biocontrol effect of B. subtilis ZSH-1, and it can be used as a promising biocontrol agent against poplar anthracnose and other fungal phytopathogens.

The oxalate-degrading activity of Lactobacillus spp. isolated from different sources as the potential probiotic modulators for oxalate homeostasis

Background: Currently, diseases of the urinary system are observed in 3.5–4% of the world's population. According to WHO, the number of people suffering from this pathology doubles every 7–10 years. To date, hyperoxaluria is considered as the main risk factor for the formation of oxalate-calcium stones, which account for 75% of all kidney stones. One of the main causes of hyperoxaluria is a decrease in the number of microorganisms capable of degrading oxalates, which occurs due to the disruption of the intestinal microbiota. Oxalate-degrading bacteria include the genera Lactobacillus, Bifidobacterium, Oxalobacter formigenes etc. Searching of probiotic strains with high oxalate-degrading activity have become one of the priorities from the context of research. The aim of the present study was to isolate Lactobacillus spp from different sources and to determine their ability to degrade oxalate. Methods: A total of 23 Lactobacillus spp. from food of animal and vegetable origin were isolated with selective MRS Broth medium and further cultured on MRS Agar or Oxalate Medium with 5 g/l sodium oxalate. ANAERO test23 was used to assess the species affiliation. Oxalate-degrading activity (ODA) was measured by redox titration with KMnO4. Results: Only 7 species of isolated bacteria out of 23 showed the ability to grow on the oxalate-containing culture medium. According to the morphological and physiological-biochemical characteristics, these bacteria belonged to the genus Lactobacillus: L. nagelii – 2 spp, L. rhamnosus – 2 spp., L. frumenti - 1 spp, L. plantarum – 1 spp, L. acidophilu – 1 spp. The most active metabolizers of oxalate on Oxalate Medium were L. plantarum S3 – 42%; L. acidophilus S5 – 38%, and L. nagelii Z2 – 35%; the worst results were shown by L. rhamnosus K7 and L. nagelii S12 – both metabolized only 7% of sodium oxalate. Conclusions: The redoximetric titration with KMnO4 was adopted to evaluate the ODA of bacteria in culture media. Lactobacillus spp. isolated from different sources differs according to the level of ODA. Three promising Lactobacillus species were selected for further estimation of probiotic profile.

Probiotic Potential and Wide-spectrum Antimicrobial Activity of Lactic Acid Bacteria Isolated from Infant Feces.

In this study, we aimed to characterize lactic acid bacteria strains derived from infants' feces, to evaluate the probiotic potential and explore the wide-spectrum antimicrobial activity. Of 800 isolates, 20 inhibited the growth of enterotoxigenic Escherichia coli K88 and Salmonella enterica ATCC 13076. On the basis of 16S rRNA sequence analysis, the 20 isolates were assigned to Lactobacillus casei (7), Lactobacillus paracasei (2), Lactobacillus plantarum (4), Lactobacillus rhamnosus (2), Enterococcus avium (3), Enterococcus faecium (1), and Enterococcus lactis (1) species. In addition, 12 strains with high antimicrobial activity were investigated for the presence of probiotic properties such as physiological-biochemical characteristics, antimicrobial susceptibility, hemolytic activity, hydrophobicity, and aggregation activity. Wide-spectrum antimicrobial activity analysis revealed that approximately all tested strains inhibited the ten pathogens, and four strains (ZX221, ZX633, ZX3131, and ZX3875) had good probiotic properties and survived after being exposed to simulated gastrointestinal tract conditions. Moreover, we investigated the influence of pH on the wide-spectrum antimicrobial activity and found that four strains inhibited most pathogens at pH4.5 and pH5, whereas only ZX633 had an inhibitory effect on Bacillus subtilis ATCC 6633 and Micrococcus luteus ATCC 4698 at pH5.5. Overall, Lact. casei ZX633 had wide-spectrum antimicrobial activity and could be considered a potential probiotic.