Influence of Chitosan on the Viability of Encapsulated and Dehydrated Formulations of Vegetative Cells of Actinomycetes.

This study focuses on developing an encapsulated and dehydrated formulation of vegetative actinobacteria cells for an efficient application in sustainable agriculture, both as a fungicidal agent in crop protection and as a growth-stimulating agent in plants. Three strains of actinobacteria were used: one from a collection (Streptomyces sp.) and two natives to agricultural soil, which were identified as S3 and S6. Vegetative cells propagated in a specific liquid medium for mycelium production were encapsulated in various alginate-chitosan composites produced by extrusion. Optimal conditions for cell encapsulation were determined, and cell damage from air-drying at room temperature was evaluated. The fresh and dehydrated composites were characterized by porosity, functional groups, size and shape, and their ability to protect the immobilized vegetative cells' viability. Actinomycetes were immobilized in capsules of 2.1-2.7 mm diameter with a sphericity index ranging from 0.058 to 0.112. Encapsulation efficiency ranged from 50% to 88%, and cell viability after drying varied between 44% and 96%, depending on the composite type, strain, and airflow. Among the three immobilized and dried strains, S3 and S6 showed greater resistance to encapsulation and drying with a 4 L·min-1 airflow when immobilized in coated and core-shell composites. Encapsulation in alginate-chitosan matrices effectively protects vegetative actinobacteria cells during dehydration, maintaining their viability and functionality for agricultural applications.

Induction of Monoterpenoid Oxindole Alkaloids Production and Related Biosynthetic Gene Expression in Response to Signaling Molecules in Hamelia patens Plant Cultures.

Hamelia patens (Rubiaceae), known as firebush, is a source of bioactive monoterpenoid oxindole alkaloids (MOAs) derived from monoterpenoid indole alkaloids (MIAs). With the aim of understanding the regulation of the biosynthesis of these specialized metabolites, micropropagated plants were elicited with jasmonic acid (JA) and salicylic acid (SA). The MOA production and MIA biosynthetic-related gene expression were evaluated over time. The production of MOAs was increased compared to the control up to 2-fold (41.3 mg g DW-1) at 72 h in JA-elicited plants and 2.5-fold (42.4 mg g DW-1) at 120 h in plants elicited with SA. The increment concurs with the increase in the expression levels of the genes HpaLAMT, HpaTDC, HpaSTR, HpaNPF2.9, HpaTHAS1, and HpaTHAS2. Interestingly, it was found that HpaSGD was downregulated in both treatments after 24 h but in the SA treatment at 120 h only was upregulated to 8-fold compared to the control. In this work, we present the results of MOA production in H. patens and discuss how JA and SA might be regulating the central biosynthetic steps that involve HpaSGD and HpaTHAS genes.

Enhancing Phosphorus and Nitrogen Uptake in Maize Crops with Food Industry Biosolids and Azotobacter nigricans.

The problem of phosphorus and nitrogen deficiency in agricultural soils has been solved by adding chemical fertilizers. However, their excessive use and their accumulation have only contributed to environmental contamination. Given the high content of nutrients in biosolids collected from a food industry waste treatment plant, their use as fertilizers was investigated in Zea mays plants grown in sandy loam soil collected from a semi-desert area. These biosolids contained insoluble phosphorus sources; therefore, given the ability of Azotobacter nigricans to solubilize phosphates, this strain was incorporated into the study. In vitro, the suitable conditions for the growth of Z. mays plants were determined by using biosolids as a fertilizer and A. nigricans as a plant-growth-promoting microorganism; in vitro, the ability of A. nigricans to solubilize phosphates, fix nitrogen, and produce indole acetic acid, a phytohormone that promotes root formation, was also evaluated. At the greenhouse stage, the Z. mays plants fertilized with biosolids at concentrations of 15 and 20% (v/w) and inoculated with A. nigricans favored the development of bending strength plants, which was observed on the increased stem diameter (>13.5% compared with the negative control and >7.4% compared with the positive control), as well as a better absorption of phosphorus and nitrogen, the concentration of which increased up to 62.8% when compared with that in the control treatments. The interactions between plants and A. nigricans were observed via scanning electron microscopy. The application of biosolids and A. nigricans in Z. mays plants grown in greenhouses presented better development than when Z. mays plants were treated with a chemical fertilizer. The enhanced plant growth was attributed to the increase in root surface area.

Nanoemulsified Formulation of Cedrela odorata Essential Oil and Its Larvicidal Effect against Spodoptera frugiperda (J.E. Smith).

Cedrela odorata L. is a plant species from the Meliaceae family that is cultivated for timber production. Although the C. odorata essential oil (EO) contains mainly sesquiterpenes, its insecticidal potential is unknown. The lipophilic properties and high degradation capacity of EOs have limited their application for use in pest control. However, the currently available knowledge on the nanoemulsification of EOs, in addition to the possibility of improving their dispersion, would allow them to prolong their permanence in the field. The objective of the present work was to develop a nanoemulsion of the C. odorata EO and to evaluate its larvicidal activity against Spodoptera frugiperda. The EO was obtained by the hydrodistillation of C. odorata dehydrated leaves, and the nanoemulsion was prepared with non-ionic surfactants (Tween 80 and Span 80) using a combined method of agitation and dispersion with ultrasound. The stability of the nanoemulsion with a droplet diameter of <200 nm was verified in samples stored at 5 °C and 25 °C for 90 days. Both the C. odorata EO and its corresponding nanoemulsion presented lethal properties against S. frugiperda. The results obtained provide guidelines for the use of wood waste to produce sustainable and effective insecticides in the fight against S. frugiperda. In addition, considering that a phytochemical complex mixture allows the simultaneous activation of different action mechanisms, the development of resistance in insects is slower.

Polymeric Encapsulate of Streptomyces Mycelium Resistant to Dehydration with Air Flow at Room Temperature.

Encapsulation is one of the technologies applied for the formulation of biological control agents. The function of the encapsulating matrix is to protect the biological material from environmental factors, while dehydration allows for its viability to be prolonged. An advantage of dehydrated encapsulation formulations is that they can be stored for long periods. However, vegetative cells require low-stress dehydration processes to prevent their loss of viability. Herein we describe the fabrication of a dehydrated encapsulate of the Streptomyces CDBB1232 mycelium using sodium alginate with a high concentration of mannuronic acid; sodium alginate was added with YGM medium for mycelium protection purposes. The encapsulation was carried out by extrusion, and its dehydration was carried out in a rotating drum fed with air at room temperature (2-10 L min-1). The drying of the capsules under air flows higher than 4 L min-1 led to viability loss of the mycelium. The viability loss can be decreased up to 13% by covering the alginate capsules with gum arabic. Compared to conventional dehydration processes, air moisture removal can be lengthy, but it is a low-cost method with the potential to be scaled.

Infectious and non-infectious diseases burden among Haitian immigrants in Chile: a cross-sectional study.

Chile has become a popular destination for migrants from South America and the Caribbean (low- and middle-income countries migration). Close to 200.000 Haitian migrants have arrived in Chile. Infectious and non-infectious disease burden among the Haitian adult population living in Chile is unknown. This study aimed to acquire the basic health information (selected transmissible and non-transmissible conditions) of the Haitian adult population living in Chile. A cross-sectional survey was performed, inviting Haitian-born residents in Chile older than 18 years old. Common conditions and risk factors for disease were assessed, as well as selected transmissible conditions (HIV, HBV, and HCV). 498 participants (60.4% female) from 10 communities in two regions of Chile were surveyed. Most subjects had never smoked (91.5%), and 80% drank less than one alcohol unit per month. The mean BMI was 25.6, with 45% of participants having a normal BMI (20-25). Hypertension was present in 31.5% (33% in the 25-44 age group). Prevalence of HIV was 2.4% (95 CI 1.3-4.2%), hepatitis B (HBsAg positive) was 3.4% (95 CI 2.1-5.5%), and hepatitis C was 0% (95 CI 0.0-0.9%). Quality of life showed a significant prevalence of depression and anxiety markers, particularly in those arriving in Chile less than 1 year ago. Low prevalence of obesity, diabetes, smoking, and drinking and estimated cardiovascular risk were found. Nonetheless, hypertension at a younger age, disproportionately higher prevalence of HIV and HBV infection and frequent markers of anxiety and depression were also found. Public policies for detecting and treating hypertension, HIV, and HBV screening, offering HBV vaccination, and organizing mental health programs for Haitian immigrants, are urgently needed.

A soft sensor based on online biomass measurements for the glucose estimation and control of fed-batch cultures of Bacillus thuringiensis.

On bioprocess engineering, experimental measurements are always a costly part of the modeling effort; therefore, there is a constant need to develop cheaper, simpler, and more efficient methodologies to exploit the information available. The aim of the present work was to develop a soft sensor with the capacity to perform reliable substrate predictions and control in microbial cultures of the fed-batch type, using mainly microbial growth data. This objective was achieved using dielectric spectroscopy technology for online monitoring of microbial growth and hybrid neural networks for online prediction of substrate concentration. The glucose estimator was integrated to a fuzzy logic controller to control the substrate concentration in a fed-batch experiment. Dielectric spectroscopy is a technology sensitive to the air volume fraction in the culture media and the turbulence generated by the agitation; however, the introduction of a polynomial function for the calibration of the permittivity signal allowed biomass estimations with an approximation error of 2%. The methodology presented in this work was successfully implemented for the glucose prediction and control of a fed-batch culture of Bacillus thuringiensis with an approximation error of 6%.

Bio-insecticide Bacillus thuringiensis spores encapsulated with amaranth derivatized starches: studies on the propagation "in vitro".

Bacillus thuringiensis (Bt) is one of the bioinsecticides used worldwide due to its specific toxicity against target pests in their larval stage. Despite this advantage, its use is limited because of their short persistence in field when exposed to ultra violet light and changing environmental conditions. In this work, microencapsulation has been evaluated as a promising method to improve Bt activity. The objective of this study was to develop and characterize native and modified amaranth starch granules and evaluate their potential application as wall materials in the microcapsulation of B thuringiensis serovar kurstaki HD-1 (Bt- HD1), produced by spray drying. Native amaranth starch granules were treated by hydrolyzation, high energy milling (HEM) and were chemically modified by phosphorylation and succinylation. The size of the Bt microcapsules varied from 12.99 to 17.14 µm adequate to protect the spores of Bt from ultraviolet radiation. The aw coefficient of the microcapsules produced by the modified starches after drying was low (0.14-1.88), which prevent microbial growth. Microcapsules prepared with phosphorylated amaranth starch presented the highest bacterial count and active material yield. Different concentrations of the encapsulated Bt formulation in phosphorylated amaranth starch showed a high level of insecticidal activity when tested on M. sexta larvae and has great potential to be developed as a bioinsecticide formulation, also, the level of toxicity is much higher than that found in some of the products commercially available.

Small microcapsules of crystal proteins and spores of Bacillus thuringiensis by an emulsification/internal gelation method.

This paper describes a microencapsulation process of a spore crystal aggregate produced by Bacillus thuringiensis var. kurstaki HD-1. The methodology is based on the emulsification/internal gelation method, and was implemented to produce microcapsules of small diameter (< 10 µm) with the capacity to protect the spore crystal aggregate from extreme ultraviolet radiation. The diameter of microcapsules was in the range of 3.1 ± 0.2-6.8 ± 0.4 µm, which is considered adequate for biological control purposes. The protective effect of the alginate coat was verified by the remaining 60 ± 2% and 40 ± 1% of spore viability and protein activity, respectively, after UV-B radiation of 236 J, and with bioassays with Spodoptera frugiperda. It is expected that the protective effect of the alginate coat will improve the effectiveness of the Bt-HD1 formulated as small diameter microcapsules, and their yield, once they are released into the environment, will also be improved.

Design of a new rotating drum bioreactor operated at atmospheric pressure on the bioremediation of a polluted soil.

This paper reports the effect of the operation and design characteristics of rotating drum bioreactors (RDBs) aerated by natural convection and applied to the treatment of a soil highly polluted with weathered total petroleum hydrocarbons (TPH) (55,000 +/- 2,600 mg/kg). The parameters studied were length to diameter ratio (L/D), rotating speed (N) and lifter type. The highest TPH removal (59.6 +/- 0.7%) was obtained with the RDB of the lowest L/D ratio (1.5). Removals diminished by 27, 36 and 56%, with a ratio increment of 2.1, 3.1 and 5.1, respectively. Increment of the N, at an optimal value and lifter change from straight to helicoidal showed an improvement on the TPH removal of 20 and 30%, respectively. According to these results, slurry surface renewal through the variation of the N and the change of slurry flow was able to improve TPH removal in RDBs operated by natural convection.

Oxygen transfer to slurries treated in a rotating drum operated at atmospheric pressure.

The objective of this work was to determine (1) the effect of rotational speed (N) and lifters on the oxygen transfer coefficient (k (L)) of a mineral solution and (2) the effect of solids concentration of a slurry soil-mineral solution on k (L), at a fixed value N (0.25 s(-1)); in both cases the treatment was carried out in an aerated rotating drum reactor (RDR) operated at atmospheric pressure. First, the k (L) for the mineral solution was in the range 6.38 x 10(-4)-7.69 x 10(-4) m s(-1), which was of the same order of magnitude as those calculated for closed rotating drums supplied with air flow. In general, k (L) of RDR implemented with lifters was superior or equal to that of RDR without lifters. For RDR implemented with lifters, k (L) increased with N in the range 6.65 x 10(-4)-10.51 x 10(-4) m s(-1), whereas k (L) of RDR without lifters first increased with N up to N = 0.102 s(-1), and decreased beyond this point. Second, regarding soil slurry experiments, an abrupt fall of k (L) (ca. 50%) at low values of the solid concentration (C (v)) and an asymptotic pattern at high C (v) were observed at N = 0.25 s(-1). These results suggest that mass transfer phenomena were commanded by the slurry properties and a semi-empirical equation of the form Sh = f(Re, Sc) seems to corroborate this finding.