Bionematicides in Brazil: an emerging and challenging market

Management of plant parasitic nematodes in Brazil is a challenge and bionematicides are an important tool in the Integrated Nematode Management in several crops. There are 47 commercial bionematicides with 11 microorganisms as active ingredient available for growers in Brazil; Bacillus spp. are the main biological control agents, but fungi are also important for nematode management. Bionematicides reached 82% of the total market of nematicides in 2019/2020 in Brazil and, in soybean, they represented 90% of the area treated with nematicides. Although, the use of bionematicides is considered an emerging market worldwide, some challenges involve the correct use and formulation of organisms with different modes of action, difficulties in laboratory culturing, and the existence of non-regulated bionematicides, which do not ensure the quality, the purity, and the efficiency in the nematode control under field conditions, leading to lack of control and discredit of this tool. Considering the Brazilian biodiversity richness, a universe of new macroand microorganisms can be explored, as well as the metabolites produced by these organisms as the active ingredient of bionematicides. Expectations of an increase in this market are optimistic and may materialize in light of the increasing demand for biological products in Brazil.

Fuzzy-Based Temperature Controller for Culturing Mesophilic and Thermophilic Bacterial using Firing Angle

Temperature control is an important parameter in the fields of engineering and medical Laboratory. Culturing of micro bacteria and enzymes for the purpose of medical diagnoses or process development in manufacturing industries require their optimum temperature to be monitored and control. In this research work Fuzzy logic controller was designed to control the incubator Temperature, by computing appropriate firing angle. MATLAB Simulink toolbox was used for simulation. The results show that the fuzzy logic controller tracks the optimum Temperature for culturing Mesophilic and Thermophilic bacteria at 37.5oC and 55.2oC respectively. The transient response shows an overshot of 0.5% for the two responses. The rise time were 787ms and 792ms for 310.5 Kelvin and 328.2 Kelvin respectively. The settling time for the 310.5 Kelvin response was 1s; whereas it took 2s for the 328.2 Kelvin response to attain steady state.

Mycobacterium tuberculosis H2S Functions as a Sink to Modulate Central Metabolism, Bioenergetics, and Drug Susceptibility

H2S is a potent gasotransmitter in eukaryotes and bacteria. Host-derived H2S has been shown to profoundly alter M. tuberculosis (Mtb) energy metabolism and growth. However, compelling evidence for endogenous production of H2S and its role in Mtb physiology is lacking. We show that multidrug-resistant and drug-susceptible clinical Mtb strains produce H2S, whereas H2S production in non-pathogenic M. smegmatis is barely detectable. We identified Rv3684 (Cds1) as an H2S-producing enzyme in Mtb and show that cds1 disruption reduces, but does not eliminate, H2S production, suggesting the involvement of multiple genes in H2S production. We identified endogenous H2S to be an effector molecule that maintains bioenergetic homeostasis by stimulating respiration primarily via cytochrome bd. Importantly, H2S plays a key role in central metabolism by modulating the balance between oxidative phosphorylation and glycolysis, and it functions as a sink to recycle sulfur atoms back to cysteine to maintain sulfur homeostasis. Lastly, Mtb-generated H2S regulates redox homeostasis and susceptibility to anti-TB drugs clofazimine and rifampicin. These findings reveal previously unknown facets of Mtb physiology and have implications for routine laboratory culturing, understanding drug susceptibility, and improved diagnostics.

Mycobacterium tuberculosis H2S functions as a sink to modulate central metabolism, bioenergetics, and drug susceptibility

H2S is a potent gasotransmitter in eukaryotes and bacteria. Host-derived H2S has been shown to profoundly alter M. tuberculosis (Mtb) energy metabolism and growth. However, compelling evidence for endogenous production of H2S and its role in Mtb physiology is lacking. We show that multidrug-resistant and drug-susceptible clinical Mtb strains produce H2S, whereas H2S production in non-pathogenic M. smegmatis is barely detectable. We identified Rv3684 (Cds1) as an H2S-producing enzyme in Mtb and show that cds1 disruption reduces, but does not eliminate, H2S production, suggesting the involvement of multiple genes in H2S production. We identified endogenous H2S to be an effector molecule that maintains bioenergetic homeostasis by stimulating respiration primarily via cytochrome bd. Importantly, H2S plays a key role in central metabolism by modulating the balance between oxidative phosphorylation and glycolysis, and functions as a sink to recycle sulfur atoms back to cysteine to maintain sulfur homeostasis. Lastly, Mtb-generated H2S regulates redox homeostasis and susceptibility to anti-TB drugs clofazimine and rifampicin. These findings reveal previously unknown facets of Mtb physiology and have implications for routine laboratory culturing, understanding drug susceptibility, and improved diagnostics.

Iron Flocs and the Three Domains: Microbial Interactions in Freshwater Iron Mats

ABSTRACTFreshwater iron mats are dynamic geochemical environments with broad ecological diversity, primarily formed by the iron-oxidizing bacteria. The community features functional groups involved in biogeochemical cycles for iron, sulfur, carbon, and nitrogen. Despite this complexity, iron mat communities provide an excellent model system for exploring microbial ecological interactions and ecological theories in situ. Syntrophies and competition between the functional groups in iron mats, how they connect cycles, and the maintenance of these communities by taxons outside bacteria (the eukaryota, archaea, and viruses) have been largely unstudied. Here, we review what is currently known about freshwater iron mat communities, the taxa that reside there, and the interactions between these organisms, and we propose ways in which future studies may uncover exciting new discoveries. For example, the archaea in these mats may play a greater role than previously thought as they are diverse and widespread in iron mats based on 16S rRNA genes and include methanogenic taxa. Studies with a holistic view of the iron mat community members focusing on their diverse interactions will expand our understanding of community functions, such as those involved in pollution removal. To begin addressing questions regarding the fundamental interactions and to identify the conditions in which they occur, more laboratory culturing techniques and coculture studies, more network and keystone species analyses, and the expansion of studies to more freshwater iron mat systems are necessary. Increasingly accessible bioinformatic, geochemical, and culturing tools now open avenues to address the questions that we pose herein.

Ovocidal action of glutaraldehyde and benzalkonium chloride mixture on Aonchotheca bovis (Nematoda, Capillariidae) embryogenesis

Deinvasion, aimed at elimination of environmental exogenic stages of invasion agents and avoidance of their invasion to host organism, occupies an important place in the complex of sanitary and prophylactic activities against animal helminthosis diseases. Application of glutaraldehyde and benzalkonium chloride at vital activity and embryogenesis of Aonchotheca bovis (Schnyder, 1906) obtained from nematode female gonads was investigated with different concentration and exposures. Two test-cultures were used in the experiment. The first culture contained non-invasive eggs of A. bovis, the second contained invasive ones, obtained by the laboratory culturing of gonadic eggs until mobile larva maturing. It was established that glutaraldehyde and benzalkonium chloride mixture has a deinvasive capacity against A. bovis eggs, parasitizing on sheep. Ovocidal efficiency indexes appeared higher with use of the test culture against the non-invasive capillaria eggs’ test-culture. So, the high level of ovocidal efficiency of glutaraldehyde and benzalkonium chloride mixture against non-invasive A. bovis eggs culture was established at the concentration of 0.5% and exposure of 10–60 min (93.6–100.0%), and against the invasive A. bovis egg culture – at the concentration of 0.5% and exposure of 30 and 60 min (90.3–94.6%) and 1.0% at all exposures (100.0%). Ovocidal activity of the examined mixture was accompanied by specific morphological changes of nematode eggs structure. Destruction of the egg envelope, embryo loosening and decay and its dissolution were observed. Such changes are proved by metric indexes of width and length of capillaria eggs, envelope thickness and cap length, indicating the violation of embryogenesis of A. bovis. Thus, glutaraldehyde and benzalkonium chloride mixture of 1.0% concentration is a promising deinvasive agent suitable for effective fight against and prophylaxis of sheep-breeding nematodosis.

Diet influence on mechanisms of non-specific stress-response in Baikal endemic amphipod species during long-term laboratory exposure

The purpose of this study was to estimate one of the important aspects of amphipod laboratory culturing — the effect of different types of nutrition on the key biochemical markers widely used in biomonitoring. The study was performed with the Baikal endemic amphipod species Eulimnogammarus verrucosus (Gerstfeldt, 1858), E. cyaneus (Dybowski, 1874), and Gmelinoides fasciatus (Stebbing, 1899). These species are characterized by different ecological properties and evolutionary history. The results of the study demonstrate that a long-term laboratory exposure to different diets has a direct effect on vital and physiological parameters of the species’ adaptation (mortality, weight, protein concentration). Also, feeding imposes its influence on the common stress-markers of oxidative stress (activities of peroxidase, catalase, glutathione S-transferase), and on anaerobic metabolism (activity of lactate dehydrogenase) in Baikal amphipods, and this effect has a species-specific character. The results should be taken into consideration in future ecophysiological experiments performed with amphipods.

Genome Assembly of the A-Group Wolbachia in Nasonia oneida Using Linked-Reads Technology

Wolbachia are obligate intracellular bacteria which commonly infect various nematode and arthropod species. Genome sequences have been generated from arthropod samples following enrichment for the intracellular bacteria, and genomes have also been assembled from arthropod whole-genome sequencing projects. However, these methods remain challenging for infections that occur at low titers in hosts. Here we report the first Wolbachia genome assembled from host sequences using 10× Genomics linked-reads technology. The high read depth attainable by this method allows for recovery of intracellular bacteria that are at low concentrations. Based on the depth differences (714× for the insect and 59× for the bacterium), we assembled the genome of a Wolbachia in the parasitoid jewel wasp species Nasonia oneida. The final draft assembly consists of 1,293, 06 bp in 47 scaffolds with 1,114 coding genes and 97.01% genome completeness assessed by checkM. Comparisons of the five Multi Locus Sequence Typing genes revealed that the sequenced Wolbachia genome is the A1 strain (henceforth wOneA1) previously reported in N. oneida. Pyrosequencing confirms that the wasp strain lacks A2 and B types previously detected in this insect, which were likely lost during laboratory culturing. Assembling bacterial genomes from host genome projects can provide an effective method for sequencing bacterial genomes, even when the infections occur at low density in sampled tissues.

Feeding Dimorphism in a Mycophagous Nematode, Bursaphelenchus sinensis

Phenotypic plasticity has been widely reported in animals and can drive investment in new biological characters that engender ecological adaptability. The nematode family Diplogastridae, especially Pristionchus pacificus with its dramatic stomatal (feeding) dimorphism, has become an important model system to analyze the evolutionary and developmental aspects of polyphenism. However, this plasticity has not been confirmed in other nematode groups. In the present study, we experimentally examined the feeding dimorphism of a fungal feeding free-living nematode, Bursaphelenchus sinensis. In a laboratory culturing experiment, the nematode expressed dimorphism, i.e., a small proportion of the population manifested as a predatory form. This form only occurred in females and was not clearly influenced by the presence of potential prey species. In addition, the ratio of the predatory form to the mycophagous form varied among different fungal food species grown in monoculture on different culture media. The predatory form of B. sinensis was typologically similar to the monomorphic (specialized) predators belonging to the same family. However, some essential morphological characters were slightly different from the specialized predators, and their behaviours were clearly disparate, suggesting that predation in B. sinensis is derived from a different phylogenetic origin than that of the specialized predators.

Studying the candida resistance and sensitivity for some antifungals

Back ground: The current study included 150 samples from patients with Candida from a hospital of Medical City / education labs - Baghdad, and ranged in age from (10 – 65(years for both sexes, all isolates taken from different sources (Lower respiratory tract, Urine, Skin, Vaginal and Oral thrux), where the number of males (55(as a percentage (37%) while the number of females (95) as a percentage (63%). The objective: The objectives of this study are studying resistance and sensitivity of candida spp to some antifungals. Material and methods: All the required material which used for the study, and the direct examination was conducted using potassium hydroxide KOH 10%, As well as microscopic examination and laboratory transplantation for all samples, for the purpose of investigating the candidiasis. Also Vitek System examination was conducted on all positive samples for microscopy and laboratory culturing; and so to be diagnosed on the species level, and this study included using (3) anti-fungal equipped from Himedia (India), an (Fluconazole, Clotrimazole and Nystatin), anti-fungal used by standard disk Diffusion to know the resistance of Candida and its sensitivity toward used anti-fungal. The results: The results of direct examination were vaginal swab (50), Sputum (28), Oral swab (34), Urine (21) and Skin swab (17). Conclusion: Candidiasis was more common in female patients as well as from medical units, where the rate of infection in females more than in males, Candida species were identified by the manual and automated methods and we found that the automated method by using VITEK2 YST Card was the best for species identification.