Microbial Growth and Decay: A Commented Review of the Model

The paper reviews previous publications and reports some comments about a semi empirical model of the growth and decay process of a planktonic microbial culture. After summarizing and reshaping some fundamental mathematical expressions, the paper highlights the reasons for the choice of a suitable time origin that makes the parameters of the model self-consistent. Besides the potential applications to predictive microbiology studies and to effects of bactericidal drugs, the model allows a suitable proxy of the fitness of the microbial culture, which can be of interest for the studies on the evolution across some thousand generations of a Long Term Evolution Experiment.

Gut microbiota-astrocyte axis: new insights into age-related cognitive decline

With the rapidly aging human population,age-related cognitive decline and dementia are becoming increasingly prevalent worldwide.Aging is considered the main risk factor for cognitive decline and acts through alterations in the composition of the gut microbiota,microbial metabolites,and the functions of astrocytes.The microbiota–gut–brain axis has been the focus of multiple studies and is closely associated with cognitive function.This article provides a comprehensive review of the specific changes that occur in the composition of the gut microbiota and microbial metabolites in older individuals and discusses how the aging of astrocytes and reactive astrocytosis are closely related to age-related cognitive decline and neurodegenerative diseases.This article also summarizes the gut microbiota components that affect astrocyte function,mainly through the vagus nerve,immune responses,circadian rhythms,and microbial metabolites.Finally,this article summarizes the mechanism by which the gut microbiota–astrocyte axis plays a role in Alzheimer’s and Parkinson’s diseases.Our findings have revealed the critical role of the microbiota–astrocyte axis in age-related cognitive decline,aiding in a deeper understanding of potential gut microbiome-based adjuvant therapy strategies for this condition.

Effects of Microbial Fermented Feed on Growth and Development of Farmed Crayfish

Microbial fermented feed possesses a natural fermentation flavor and exhibits good palatability.It is not only easily digestible and absorbable by livestock but also non-toxic.Additionally,it has the capacity to inhibit the proliferation of pathogenic bacteria,facilitate the growth and development of animals,and enhance their immune response,disease resistance,and overall production performance.This paper summarizes the selection of common feed materials and microbial strains used in fermented feed,as well as their effects on the growth performance,muscle quality,antioxidant capacity,and immune function of crayfish.The aim of this study is to provide a reference for the further popularization and application ofmicrobialfermented feed in crayfishaquaculture.

Effect of Microbial Inoculum Fertilizer on the Growth and Yield of Super Hybrid Rice

The research designed four application quantities of 0, 2 250, 4 500 and 6 750 g/hm2 based on Liangyou No. 959 to explore the effects of microbial inocu- lure fertilizer on growth and yield of super hybrid rice. The results indicate that the treatment with traditional fertilizers and 4 500 g/hm2 HYT microbial inoculum fertilizer performed the best, where average number of tiller was 2.4 more than that of the control; the number of effective ear was 11.05% higher; yield increased by 10.3%. These have demonstrated that microbial inoculum fertilizer is of great value in pro- motion on super hybrid rice production.

Recent tree growth decline unprecedented over the last four centuries in a Tibetan juniper forest

Forest structure and function are subject to risks of growth declines from intensified drought and frequent extreme events related to climate warming.Knowledge of tree growth declines will help anticipate future responses of forests to climate change.In this study,we investigated tree growth declines over the last four centuries in a juniper forest on the eastern Tibetan Plateau.By analyzing the radial growth trajectories of individual trees,we identified two events of intense growth decline,one in 1817–1830 and the other in 1969–1999 over the past four centuries.The intensity of the recent decline was unprecedented in the period under study.Ring-width chronology showed a positive correlation with self-calibrating Palmer Drought Severity Indices and a negative correlation with mean monthly temperatures in May and June.The recent intensified growth decline may have been due to temperatureinduced frequent droughts in the study area.Our findings suggest that trees in this juniper forest may face a higher risk of growth decline and even mortality under continued climate warming.

Effects of spaceflight and simulated microgravity on microbial growth and secondary metabolism

Spaceflight and ground-based microgravity analog experiments have suggested that microgravity can affect microbial growth and metabolism. Although the effects of microgravity and its analogs on microorganisms have been studied for more than 50 years, plausible conflicting and diverse results have frequently been reported in different experiments, especially regarding microbial growth and secondary metabolism. Until now, only the responses of a few typical microbes to microgravity have been investigated; systematic studies of the genetic and phenotypic responses of these microorganisms to microgravity in space are still insufficient due to technological and logistical hurdles. The use of different test strains and secondary metabolites in these studies appears to have caused diverse and conflicting results. Moreover, subtle changes in the extracellular microenvironments around microbial cells play a key role in the diverse responses of microbial growth and secondary metabolisms. Therefore, "indirect" effects represent a reasonable pathway to explain the occurrence of these phenomena in microorganisms. This review summarizes current knowledge on the changes in microbial growth and secondary metabolism in response to spaceflight and its analogs and discusses the diverse and conflicting results. In addition, recommendations are given for future studies on the effects of microgravity in space on microbial growth and secondary metabolism.

Intrauterine growth restriction alters growth performance, plasma hormones,and small intestinal microbial communities in growing-finishing pigs

Background: The interaction of the gut microbiota with key metabolic and physiological processes may be associated with poor growth outcomes in animals born with intrauterine growth restriction(IUGR).Results: Growth performance, plasma hormone concentrations, and intestinal microbiota composition were analyzed in IUGR pigs and in normal birth weight(NBW) pigs when the NBW pigs reached 25, 50, and 100 kg of body weight(BW). Compared to NBW pigs, IUGR pigs had lower initial, weaned, and final BW, and lower average daily gain and average daily feed intake in all the considered time points. In the 25 kg BW group, IUGR pigs had higher concentrations of plasma ghrelin and pancreatic polypeptide(PP), but lower insulin concentration than NBW pigs, while the situation was reversed in the 50 kg BW group. As compared to NBW pigs, IUGR pigs had higher microbial alpha diversity in the jejunum and ileum;in the 50 and 100 kg BW groups, IUGR pigs had higher Firmicutes abundance but lower Proteobacteria abundance in the jejunum, and lower Lactobacillus abundance in the jejunum and ileum;in the 25 kg BW group, IUGR pigs showed higher unclassified Ruminococcaceae abundance in the ileum;and in 25 and 50 kg BW groups, IUGR pigs showed lower Ochrobactrum abundance in the jejunum.Spearman's correlation revealed that Lactobacillus was negatively correlated with growth performance, while unclassified Ruminococcaceae was positively correlated. Predictive metagenomic analysis detected significantly different expression of genes in the intestinal microbiota between IUGR and NBW pigs, suggesting different metabolic capabilities between the two groups.Conclusions: Growing-finishing IUGR pigs showed lower growth performance, higher microbial alpha diversity, and differences in plasma hormone concentrations compared to NBW pigs. Alterations in the abundance of Firmicutes,Proteobacteria, Ruminococcaceae, Lactobacillus, and Ochrobactrum in the small intestine may be associated with IUGR, and may therefore serve as a future target for gut microbiota intervention in growing-finishing IUGR pigs.

Effect of carbon and nitrogen ratio control on Artemia growth, water quality, biofloc microbial diversity under high salinity and zero-water exchange culture condition

Biofloc technology has been applied successfully in the intensive aquaculture of several fish and shrimp species. The growth of heterotrophic microorganisms can be stimulated through adding extra carbon, which reduces the nitrogen level in the water and provides microbial protein to the animals. However, most of the studies and practical applications have been conducted in freshwater and marine environment. This paper focused on brine shrimp Artemia that lives in high salinity environment together with other halophilic or halotolerant microorganisms. The effect of carbon supplementation on Artemia growth, water quality, and microbial diversity of biofl ocs was studied in the closed culture condition without any water exchange. The salinity of the culture medium was 100. A 24-d culture trial was conducted through supplementing sucrose at carbon/nitrogen (C/N) ratio of 5, 15, and 30 (Su5, Su15, and Su30), respectively. The culture without adding sucrose was used as a control. Artemia was fed formulated feed at a feeding ration of 60% recommended feeding level. The results showed that sucrose supplementation at higher C/N ratio (15 and 30) signifi cantly improved the Artemia survival, growth and water quality ( P <0.05). Addition of sucrose at C/N ratio of 15 and 30 significantly increased biofloc volume (BFV)( P <0.05). The Illumina MiSeq sequencing analysis showed that supplementing carbon at C/N ratio of 15 had a better total bacterial diversity and richness, and shaped the microbial composition at genera level. This study should provide information for studying the mechanism of biofloc technology and its application in high salinity culture conditions.

Nursery practice on seed germination and seedling growth of Dalbergia sissoo using beneficial microbial inoculants

Nursery practice using microbial inoculants was performed to find out the efficacy of the inoculants on seed germination and seedling growth of sissoo（Dalbergia sissoo Roxb.）.Microbial inoculants or effective microorganisms（EM） are a mixture of many different beneficial microorganisms in a solution.The seedlings were grown in a mixture of sandy soil and cowdung（3：1） kept in polybags with pouring EM solution at different concentrations（0.1%,0.5%,1%,2%,5% and 10%） before and after a week of sowing the seeds.Seed germination rate and growth parameters of seedlings were measured,such as,shoot and root length,vigor index,fresh and dry weight of shoot and root and total biomass increment.The nodulation status influenced by EM was also observed along with the measurement of pigment contents in leaves.The highest germination rate（69%） was observed in 2% EM treatment,followed by 67% and 65% in 1% and 5% EM.The highest shoot length（33.2 cm） was in 2% EM,whereas highest root length（26.3 cm） was in 1% EM.Both fresh and dry weights from shoot and root,were maximum（4.16 g and 1.57 g;2.12 g and 0.83 g respectively） in 2% EM and were significantly（p ≤ 0.05） different from control.Vigor index was highest（4071） in 2% EM,which was significantly（p ≤ 0.05） different from control.Total dry weight increment was highest in 2% EM treatment,followed by 1% and 5% concentrations of EM.Nodulation number was higher at very low（0.1%） concentration of EM solution but it normally decreased with the increase of EM concentrations.The contents of chlorophyll a,chlorophyll b and carotenoid were highest（60.11,17.05 and 42.48 mg·L1respectively） in 2% EM treatment and lowest（39.35,13.55 and 27.29 mg·L-1 respectively） in control treatment.Therefore,low concentration of EM（up to 2%） can be used for getting maximum seed germination rate and seedling development of Dalbergia sissoo Roxb.

Effect of microbial inoculants on Albizia saman germination and seedling growth

Microbial Inoculants as Effective Microorganisms （EM） were applied to find out their effects on germination and seedling growth of Albizia saman in the nursery. The seedlings were grown in a mixture of sandy soils and cow dung （3：1） kept in polybags. The EM solution at different concentrations （0.1%, 0.5%, 1%, 2%, 5% and 10%） was incorporated before and after a week of sowing seeds. Germination and physical growth parameters, including shoot and root length, vigor index, collar diameter, leaf number, fresh and dry weight of shoot and root and total biomass increment over the control were measured. The nodulation status influenced by EM was also observed along with the estimation of chemical parameters like chlorophyll a, chlorophyll b and carotenoid. Both germination and the measured physical growth parameters were found significantly （P〈0.05） higher in seedlings treated with different concentrations of EM solution in comparison to the control. Maximum growth was found at 2% followed by 1% EM solution. Nodulation was higher at 0.1% concentration but it normally decreased with the increase of concentrations. Although there were a higher amount of pigments in leaves of the treated seedlings than of the control, the variations recorded with respect to chlorophyll a, b and carotenoid were not significantly higher in most of the treatments. Treated seedlings showed variable results along with the increment of EM applications and most of the parameters showed best results at the medium range of concentrations. The study indicates that the Microbial Inoculant （EM） technology might be useful to improve the growth of seedlings in the nursery. This also indicates that the associated beneficial organisms along with the polybag soils might be of value in improving the degraded soil or poor field soil for better nutrient and water uptake during the initial growth of transplanted seedlings.

Effects of Microbial Fertilizer on Growth Characteristics of Facility Tomato and Chemical Properties of Acidic soil

[Objectives]This study was conducted to discuss the possibility of applying microbial fertilizer to production of facility tomato,so as to determine rational application rate for facility tomato.[Methods]A field experiment was carried out to investigate the effects of the application of microbial fertilizer onto acidic soil on yield,quality and soil chemical properties of facility tomato.[Results]Yield of facility tomato was improved after the application of microbial fertilizer.Treatment ABA-2 showed the highest yield,which was higher than the CK by 7.98%.On the basis of conventional fertilization,the combined application with microbial fertilizer could promote growth and development of tomato,and could significantly improve fruit weight,and Vc,soluble solid and lycopene contents.Furthermore,the microbial fertilizer could remarkably improve soil p H,alkali-hydrolyzale nitrogen,available phosphorus and rapidly available potassium contents.[Conclusions]The application of microbial fertilizer at 80 kg/667 m^(2) has better effects on tomato growth and development and soil status.

Study on Growth and Decline Law of Contagious Pleuro-pneumonia in Piglets

In order to establish the immune procedure for Actinobacillus pleuropneumonia and to determine the date for the first immunization on piglets, the growth and decline law of A. pleuropneumonia material antibodies in the piglets borne by cows inoculated with A. pleuropneumonia vaccines （type I, II, and VII） before delivery was detected. The results showed that type I, II, and VII maternal antibodies in piglets decreased gradually with the age growing overall, and was at the critical protection value at the ages of 42-50 days （type I） and 28 days （type VII）, lower than the quantification rate; and the antibodies all turned to be negative until the ages of 70 days （type I）, 60 days （type VII） and 35 days （type II）. The first immunization should be carried out at the age of 42-50 days using type I A. pleuropneumonia vaccine, and at the age of 28 days using type VII A. pleuropneumonia vaccine. However, type II A. pleuropneumonia maternal antibody had lower level and positive rate and could not well protect piglets, so the various A. pleuropneumonia vaccines differed in the date for the first immunization. In order to achieve a better immunization effect, A. pleuropneumonia vaccines with different valences should be further researched and developed.

Effects of Microbial Inoculants from Sewage Sludge on Initial Growth of Festuca arundinacea L.

Microbial inoculants were isolated from sewage sludge and applied to turfgrass medium. Effects of microbial inoculants on seed germination and initial growth of Festuca arundinacea L. were analyzed to investigate the optimal proportion of compound microbial inoculants. Significant differences were found in various growth indices and chlorophyll content of F. arundinacea between microbial treatment and control The combination of Pseudomonas stutzeri and Trichoderma reesei exhibited the best results. Compared with the control, seed germination rate, seedling height, shoot dry weight, root weight, chlorophyll a content and chlorophyll b content of F. arundinacea treated with the combination of Pseudomonas stutzeri and Trichoderma reesei were improved by 11.60%, 43.47%, 148%, 159%, 144% and 136%, respectively. Based on comprehensive analysis of various indicators, the optimal proportion （V/V） of microbial combination was Pseudomonas stutzeri： Tfichoderma reesei = 1： 1, which was the most conducive to plant growth and development.

A pressure-calibration method of wavelength modulation spectroscopy in sealed microbial growth environment

A new pressure-calibration method for calibrating the reduction of second harmonic(2f)amplitude caused by pressure broadening effect in sealed microbial growth environment is present.The new method combines with linewidth compensation and modulation depth compensation and makes the 2f amplitude accurately retrieve metabolic CO_(2) in microbial growth.In order to verify the method,a simulation experiment is developed,in which the increasing CO_(2) concentration leads to the increasing pressure.Comparing with the relation between the traditional 2f amplitude and gas concentration,there is a monotonous relation between the calibrated 2f amplitude and CO_(2) concentration,particularly,a linear relation is present when the CO_(2) concentration is replaced with the CO_(2) particle number.In terms of microbial measurement,the growth of Escherichia coli is measured,and the culture bottle is sealed during the microbial growth process.The experimental results show that,comparing to the microbial growth retrieved by traditional 2f amplitude,the calibrated 2f amplitude can accurately retrieve microbial growth in sealed environment.

Inhibition of Microbial Growth by Anilines： A QSAR Study

The relative toxicity of 48 anilines using the Tetrahymena pyriformis population growth characteristics IGC50 （concentration causing 50% growth inhibition）, available in the literature, was studied. At first, the entire data set was randomly split into a training set （31 chemicals） used to establish the QSAR model, and a test set （17 chemicals） for statistical external validation. A biparametric model was developed using, as independent variables, 3D theoretical descriptors derived from DRAGON software. The GA-MLR （genetic algorithm variable subset selection） procedure was performed on the trainingset by the software mobydigs using the OLS （ordinary least squares） regression method, and GA（genetic algorithm）-VSS（variable subset selection） by maximising the cross-validated explained variance （Q^2Loo）＇ The obtained model was examined for robustness （Q^2LOOcross-validation, Y-scrambling） and predictive ability through both internal （Q^2LM0, bootstrap） and external validation （Q^2ext） methods. Descriptors included in the QSAR model indicated that log/GC^-150 value was related to molecular size and shape, and interaction of molecule with its surrounding medium or its target. Moreover, the applicability domain of the model was discussed.

Porcine Breeding Management in a Large-scale Piggery with Microbial Fermentation Bed

[Objective] The behavior of eating, drinking, defecating and peeing of 1 500 pigs in a large-scale microbial fermentation bed-equipped piggery was observed. We hoped to find some simple indicators that could reflect the health status of swinery and to provide experience for the swinery performance management in large-scale microbial fermentation bed-equipped piggery. [Method] The body weight （BW）, daily BW gain, feed intake and other indicators of different-day-old pigs were recorded in details. Based on the recorded data, the models between BW, BW gain, average daily feed intake and feed/gain ratio and growth days （d） were established. In addition, the incidences of pox-like macula （dermatitis）, diarrhea （gastrointestinal disease）, cough （respiratory disease）, stiff pig （malnutrition）, conjunctivitis （eye disease） and foot inflection （trauma） among fattening pigs were also investigated. [Result] The BW range, average BW, daily BW gain, breeding days, daily feed intake range, average daily feed intake, staged feed intake, accumulated feed intake, feed/gain ratio and accumulated feed/gain ratio of different-day-old pigs were studied, respectively. Four dynamic models were established for the growth of pigs： （1） the BW （y）-age （x） mod- el： y=0.758 9x-19.883 （3=0.993 7）; （2） the BW gain （y）-age （x） model： y=1.039 5x05051 （F=0.885 4）; （3） the average daily feed intake （y）-age （x） model： y=0.023 5x-0.334 3 （F=0.991 7）; （4） the feed/gain ratio （y）-age （x） model： y=0.022x＋0.427 8 （P=0.988 5）. Based on these models, the corresponding theoretical growth value of pigs at different growth stage could be predicted. The main diseases occurred among the swinery in the large-scale microbial fermentation bed piggery included pox-like macula （dermatitis）, diarrhea （gastrointestinal disease）, cough （respiratory disease）, stiff pig （mal- nutrition）, conjunctivitis （eye disease） and foot inflection （trauma）. The deadly infec- tious diseases had been not found among the pigs. [Conclusion] When the actual BW, BW gain, average daily feed intake and feed/gain ratio were all lower than the theoretical values predicted by the models, the management should be enhanced. The average daily feed intake of 60 to 65-day-old pigs was lower than the theoretic value, indicating that the pigs could not adapt nicely to the fermentation bed at the very early stage. When the pigs grew up to 70 to 75 d old, the average daily feed intake was higher than the theoretical value, indicating that the pigs had adapted to the fermentation bed. In particularly, average daily feed intake of 75-day-old pigs was higher than the theoretical value by 21%. It was suggested the fermentation bed was conducive to the growth of pigs. Considering the occurrence of diseases among pigs, the overall incidence was relatively low. The incidence of each disease was all lower than 10% with little difficulty in treating. If the management of mattress was strength- ened, such as paying attention to feeding and keeping water clean, many diseases could heal by themselves.

Anti-microbial principles of selected remedial plants from Southern India

Objective:To examine the anti-bacterial activity of leaf extracts of Morus alba L.(Moraceae)and Piper betel L.(Piperaceae),and seed extracts of Bombax ceiba L.(Borabacaceae).Methods:We have partially purified plant extracts by solvent extraction method,and evaluated the effect of individual fractions on bacterial growth using Escherichia coli(E.coli),Pseudomonas aeruginosa(P.aeruginosa) and Staphylococcus aureus(S.aureus) bacterial strains.Results:Compared with Morus and Bombax fractions,Piper fractions showed significant growth inhibition on all the three types of bacteria studied.The EtOAc-hexane fractions of Piper leaves exhibited significant antibacterial activity with minimum inhibitory concentrations(MIC) of 50 μg/mL culture against both gram-positive and gram-negative bacteria.The EtOAc-fractions Ⅰ,Ⅱ,and Ⅳ inhibited bacterial colony formation on soft agar in addition to growth inhibition.A combination treatment of piper fractions with ampicillin resulted in significant growth inhibition in E.coli and P.aeruginosa,and combination with anticancer drug geldanamycin(2 μg/mL) showed selective growth inhibition against P.aeruginosa and S.aureus.Three major compounds,i.e.,eugenol,3-hexene-ol and stigmasterol,were primarily identified from Piper betel leaf extractions.Among the individual compounds,eugenol treatment showed improved growth inhibition compared with stigmasterol and 3-hexene-ol.Conclusions:We are reporting potential anti-bacterial compounds from Piper betel against both gram-positive and gram-negative bacteria either alone or in combination with drug treatment.

Microbial Food Safety Risks Associated with Fresh and Thawed Catfish Fillets during Refrigerated Storage

Fish processing environment is very favorable for the growth of microorganisms and highlights a potential risk associated with microbial hazards. The present study investigated the growth behavior of aerobic bacteria, yeasts and molds, and bacterial pathogens or surrogate (Listeria monocytogenes and Clostridium sporogenes) on thawed and fresh catfish fillets during refrigerated storage (5&deg;C - 7&deg;C). Thawed and fresh fillets were respectively inoculated with L. monocytogenes and C. sporogenes, and packaged in LDPE bags. In uninoculated catfish, the populations of aerobic bacteria, and yeasts and molds increased significantly (P C. sporogenes vegetative cells on fresh catfish fillets. These results indicated that the microbiological quality of refrigerated thawed catfish would become unacceptable within 3 - 4 days. Our results also implied that environmental pathogens such as L. monocytogenes and Clostridium sp. can survive on catfish fillets for extended periods during refrigerated storage. Proper sanitation and hygienic practices are essential to control microbial hazards during handling and processing of catfish fillets.

Nutritional, Physicochemical and Microbial Quality of Ultrasound-Treated Apple-Carrot Juice Blends

Three different apple-carrot juice blends (60:40, 75:25 and 90:10, v/v) were prepared and treated with ultrasound with comparison to the conventional thermal pasteurization. Total aerobic viable count (TAC) were significantly lower in juice blends with lower pH (apple-carrot ratio of 90:10, v/v) than the blends with higher pH after one month storage at 4?C. TAC were similar in ultrasound-treated and thermal pasteurized juice blends. Changes of turbidity of juice during storage followed the same pattern of TAC. Other juice quality parameters such as color, pH, titratable acid, total soluble solids, antioxidant capacity and beta-carotene did not change significantly during the storage period. The results suggest that ultrasound treatment has a potential to use as an alternative non-thermal technique for traditional thermal pasteurization process for maintaining the quality of beverages prepared from fruit and vegetable juices.

Development of Microbial Fermented Feed and Its Effect on the Production Performance of Holstein Cows

[Objectives]This study was conducted to investigate the development method of microbial fermented feed and its effect on the production performance of Holstein cows.[Methods]Thirty Holstein cows were selected and randomly divided into 2 groups,15 cows in each group.The diet composition of the experimental group was:concentrate supplement added with 30% microbial fermented feed+silage+alfalfa hay,and the diet composition of the control group was:concentrate supplement added with 30% flax cake+silage+alfalfa hay.The experimental period was 60 d.[Results]Compared with the control group,the experimental group increased the average daily milk yield per cow by 2.25%(P>0.05)and the total increase in average milk yield per cow in the experimental period by 43.51%(P<0.01),and reduced the average feed-to-milk ratio by 9.20%(P<0.05).The average gross profit per cow of the experimental group was 40.34 yuan higher than that of the control group,showing an increase of 3.53% in the economic benefit.[Conclusions]Feeding a diet supplemented with the microbial fermented feed could improve the efficiency of Holstein cow farming and is recommended to be promoted.