Organic amendments alleviate early defoliation and increase fruit yield by altering assembly patterns and of microbial communities and enzymatic activities in sandy pear (Pyrus pyrifolia)

Severe early defoliation has become an important factor restricting the development of the pear industry in southern China. However, the assembly patterns of microbial communities and their functional activities in response to the application of bioorganic fertilizer (BIO) or humic acid (HA) in southern China’s pear orchards remain poorly understood, particularly the impact on the early defoliation of the trees. We conducted a 3-year field experiment (2017–2019) in an 18-year-old ‘Cuiguan’ pear orchard. Four fertilization schemes were tested: local custom fertilization as control (CK), CK plus HA (CK-HA), BIO, and BIO plus HA (BIO-HA). Results showed that BIO and BIO-HA application decreased the early defoliation rate by 50–60%, and increased pear yield by 40% compared with the CK and CK-HA treatments. The BIO and BIO-HA application significantly improved soil pH, available nutrient content, total enzyme activity and ecosystem multifunctionality, and also changed the structure of soil bacterial and fungal communities. The genus Acidothermus was positively correlated with the early defoliation rate, while the genus Rhodanobacter was negatively correlated. Additionally, random forest models revealed that the early defoliation rate could be best explained by soil pH, ammonium content, available phosphorus, and total enzyme activity. In conclusion, application of BIO or BIO mixed with HA could have assembled distinct microbial communities and increased total enzyme activity, leading to significant improvement of soil physicochemical traits. The increased availability of soil nutrient thus changed leaf nutrient concentrations and alleviated the early defoliation rate of pear trees in acid red soil in southern China.

Immobilization of Crude Polyphenol Oxidase Extracts from Apples on Polypyrrole as a Membrane for Phenol Removal

This research aims to make a polypyrrole (PPy) membrane and crude extract of polyphenol oxidase (PPO) as a membrane of mPPy/PPO apple extracts. The membrane of PPy/PPO-apple extract has been synthesized by the electrodeposition method. The electrolyte composition consists of a mixture of 0.10-0.20 M pyrrole (Py) and 50-100% PPO apple extract, which is stable using 50 mM of phosphate buffer solution at pH 6.80-7.00 and room temperature. The electrodeposition process is used 400 mesh steel gauze anode ST-304 and carbon plate cathode. Electrodeposition is carried out at potential = 5.00-6.00 V; current = 0.02-0.25 A; the distance from both electrodes = 1.00-2.00 cm for 300-500 seconds. The results from the deposition of PPy/PPO apple extract of the anode are a membrane of mPPy/PPO-apple extract, with total enzyme activity (U) = (957,1441, 2287 and 1754) using 2.00-5.00 mM phenol as a substrate which is measured based on the UV-visible spectrophotometric method. PPy and mPPy/PPO-apple extracts were characterized by SEM and SEM-EDS. The membrane of mPPy/PPO-apple extract can be used to remove phenol in industrial wastewater samples is 50-65% with a filtration capacity of 500 mL for 2 hours.

Isolation and selection of cellulolytic bacteria from rice straw for consortium of microbial fuel cell

Khoirunnisa NS, Anwar S, Santosa DA. 2020. Isolation and selection of cellulolytic bacteria from rice straw for consortium of microbial fuel cell. Biodiversitas 21: 1686-1696. Cellulose such as in rice straw can be utilized as an organic substrate in Microbial Fuel Cell (MFC) to generate electricity by microorganisms as a biocatalyst. This research aimed to get cellulose-degrading bacteria with high capability to degrade rice straw and able to be used as consortium with exoelectrogen bacteria in Microbial Fuel Cell. The stages of research included: (i) isolation of the bacteria using carboxymethylcellulose (CMC) agar medium, (ii) selection of the isolates for that purpose, (iii) enzyme assay and MFC performance test, and (iv) identification of selected isolate. There were 125 isolates that were obtained. Selection based on the ability to degrade cellulose as indicated by clear zone on CMC medium resulted in 23 isolates. Ten isolates belong to anaerobic facultative bacteria were selected. Three of them were synergistic with exoelectrogen bacteria. The three isolates were tested for exoglucanase (Avicel) and total enzyme activity (Filter Paper) with the highest results were 6.21 U/mL (isolate J404) and 5.88 U/mL (isolate J401), respectively. The optimum MFC performance was achieved by one isolate, J401, which produced highest voltage of 40.8 mV and a power density of 0.33 mW/m2. The best isolate, J401, was identified as Xanthomonas translucens based on 16S rRNA method.

Effects of Gas Supplying Patterns on Aerobic Anaerobic Biogas Production of Rice Straw

Background: Rice straw as a plant photosynthesis product, is a valuable renewable resource and it contains protein, fat, cellulose, hemicellulose, lignin and ash. It has received wide attention for biogas can solve both the energy and environment problems. Objective: To improve the degradation rate of rice straw in aerobic and anaerobic bi-phase fermentation process. Methods: Different aerobic methods were adopted to improve the degradation rate of aerobic acid producing cellulose. Results: The results showed that in different ways of gas supply test experiments the total enzyme activity of aeration mode was higher than that of the stirring air supply mode, which indicated that the aeration mode was more favorable to the growth of mixed strains of Trichoderma and Aspergillus. The gas production of TS was 438.69 mL•g-1, which was higher than both the stirring group and control group. Conclusion: The degradation utilization rate of rice straw solid organic matter can be significantly improved using method of aeration mode, and the conversion of straw biomass into biogas was promoted.

Two-Step Production of Neofructo-Oligosaccharides Using Immobilized Heterologous Aspergillus terreus 1F-Fructosyltransferase Expressed in Kluyveromyces lactis and Native Xanthophyllomyces dendrorhous G6-Fructosyltransferase

Fructo-oligosaccharides (FOS) are prebiotic low-calorie sweeteners that are synthesized by the transfer of fructose units from sucrose by enzymes known as fructosyltransferases. If these enzymes generate β-(2,6) glycosidic bonds, the resulting oligosaccharides belong to the neoseries (neoFOS). Here, we characterized the properties of three different fructosyltransferases using a design of experiments approach based on response surface methodology with a D-optimal design. The reaction time, pH, temperature, and substrate concentration were used as parameters to predict three responses: The total enzyme activity, the concentration of neoFOS and the neoFOS yield relative to the initial concentration of sucrose. We also conducted immobilization studies to establish a cascade reaction for neoFOS production with two different fructosyltransferases, achieving a total FOS yield of 47.02 ± 3.02%. The resulting FOS mixture included 53.07 ± 1.66 mM neonystose (neo-GF3) and 20.8 ± 1.91 mM neo-GF4.

Model-based metabolism design: constraints for kinetic and stoichiometric models

The implementation of model-based designs in metabolic engineering and synthetic biology may fail. One of the reasons for this failure is that only a part of the real-world complexity is included in models. Still, some knowledge can be simplified and taken into account in the form of optimization constraints to improve the feasibility of model-based designs of metabolic pathways in organisms. Some constraints (mass balance, energy balance, and steady-state assumption) serve as a basis for many modelling approaches. There are others (total enzyme activity constraint and homeostatic constraint) proposed decades ago, but which are frequently ignored in design development. Several new approaches of cellular analysis have made possible the application of constraints like cell size, surface, and resource balance. Constraints for kinetic and stoichiometric models are grouped according to their applicability preconditions in (1) general constraints, (2) organism-level constraints, and (3) experiment-level constraints. General constraints are universal and are applicable for any system. Organism-level constraints are applicable for biological systems and usually are organism-specific, but these constraints can be applied without information about experimental conditions. To apply experimental-level constraints, peculiarities of the organism and the experimental set-up have to be taken into account to calculate the values of constraints. The limitations of applicability of particular constraints for kinetic and stoichiometric models are addressed.

Atividade da malato desidrogenase muscular de Astyanax bimaculatus da bacia hidrográfica do rio Una como biomarcadora de impacto ambiental

The enzymatic activity of malate dehydrogenase (MDH) and its isoforms may vary in fishes according their living environment. The aim of this work was to investigate the activity of MDH in the muscle tissue of Astyanax bimaculatus (locally called as lambari do rabo amarelo), collected at three different points (P1, P2 and P3) in the Una River Basin (Taubaté, SP), to evaluate it as a candidate biomarker for environmental change. Cytosolic and mitochondrial isoforms of MDH were extracted from muscles. The results indicated that the total enzyme activity was 1.8 and 2.5 times higher in A. bimaculaus at P2, in comparison to specimens collected at P1 and P3, respectively. Seven MDH isoforms were detected in the muscle tissue (MDH-1 to MDH-7). MDH-1 levels of specimens collected at P3 were 1.9 and 2.4 times higher than those from P1 and P2, respectively. However, the levels of MDH-5, -6 and -7 of P3 specimens were significantly lower than P1 ones. These results are possibly related to water quality, considering that P3 is the most polluted among the three sampling sites. The muscle MDH activity of A. bimaculatus was modulated by the environment. Therefore, it can be concluded that this enzyme could be used as a biomarker of environmental change of the hydrographic basin of a neotropical region, where this species occurs.

EXTRACELLULAR COLD ACTIVE ENDOGLUCANASE AND PIGMENT PRODUCING PSYCHROTOLERANT PENICILLIUM PINOPHILUM

<p><strong>Objective: </strong>The objective of the present study was on <em>Penicillium pinophilum </em>strain F2 from soil samples of Jammu city having the potentiality to produce alkaline cold active endoglucanase and pigment.</p><p><strong>Methods: </strong><em>Penicillium pinophilum </em>strain F2,<em> </em>a<em> </em>psychrotolerant micro-fungus was isolated from soil of Jammu city, India by taking Czapek’s Dox agar incubated at 15 °C. The strain was screened for production of cold active enzymes by taking various substrates at 15 °C. Final production was done for cold active endoglucanase by using sugarcane bagasse and ground nut shell as substrates. Besides, the strain was also able to produce red color pigment at a low temperature which was further studied to optimize its production by changing pH and growth medium. The produced pigment was used for dyeing of wool and silk, and absorption percentages were also calculated.</p><p><strong>Results: </strong>Screening for the production of cold active enzymes revealed it as a good producer of cellulose followed by lipase and amylase. Endoglucanase production revealed the total enzyme titer (total enzyme activity) was found to be 5.032 folds higher in sugarcane bagasse (38.91 units) than groundnut shell (7.732 units). Endoglucanase activity was maximum 9.82±0.33 units/ml and 2.29±0.31 units/ml after 120 h of incubation at 15 °C by sugarcane bagasse and groundnut shells, respectively. Red color pigment production was maxima at pH 5 in Czapek’s Dox broth. Maximum absorption percentage was seen by the treatment soaked with mordant, i.e. 5% CuSO₄(51.52%) and without a mordant, it showed about 45.54%.</p><p><strong>Conclusion: </strong>Due to the above unique features and capability to produce cold active endoglucanase and pigment by strain F2, can be used significantly in various industries.</p>