Nisin variants: What makes them different and unique?

Nisin A is a lantibiotic bacteriocin typically produced by strains of Lactococcus lactis. This bacteriocin has been approved as a natural food preservative since the late 1980 s and shows antimicrobial activity against a range of food-borne spoilage and pathogenic microorganisms. The therapeutic potential of nisin A has also been explored increasingly both in human and veterinary medicine. Nisin has been shown to be effective in treating bovine mastitis, dental caries, cancer, and skin infections. Recently, it was demonstrated that nisin has an affinity for the same receptor used by SARS-CoV-2 to enter human cells and was proposed as a blocker of the viral infection. Several nisin variants produced by distinct bacterial strains or modified by bioengineering have been described since the discovery of nisin A. These variants present modifications in the peptide structure, biosynthesis, mode of action, and spectrum of activity. Given the importance of nisin for industrial and therapeutic applications, the objective of this study was to describe the characteristics of the nisin variants, highlighting the main differences between these molecules and their potential applications. This review will be useful to researchers interested in studying the specifics of nisin A and its variants.

Feline leishmaniasis in an animal shelter in northeastern Brazil: Clinical aspects, coinfections, molecular detection, and serological study of a new recombinant protein.

Infection and clinical cases of leishmaniasis caused by Leishmania infantum in cats have been increasingly reported in several countries, including Brazil. In this study, we used an enzyme-linked immunosorbent assay (ELISA) and an immunochromatographic test (ICT) based on a recombinant antigen (rKDDR-plus) to detect anti-Leishmania antibodies in cats from an animal shelter in northeastern Brazil. We compared the results with an ELISA using L. infantum crude antigen (ELISA-CA). We also investigated the presence of Leishmania DNA in blood or ocular conjunctival samples as well as the association between Leishmania PCR positivity and serological positivity to feline immunodeficiency virus (FIV), feline leukemia virus (FeLV) and Toxoplasma gondii. Concerning serological assays, a higher positivity was detected using the ICT-rKDDR-plus (7.5%; 7/93) as compared to ELISA-rKDDR-plus (5.4%; 5/93) and ELISA-CA (4.3%; 4/93). Upon PCR testing, 52.7% (49/93) of the ocular conjunctival swabs and 48.3% (44/91) of the blood samples were positive. Together, PCR and serological testing revealed overall positivities of 73.1% (68/93) and 12.9% (12/93), respectively. Among PCR-positive samples, 45.5% (31/68) showed co-infection with FIV, 17.6% (12/68) with FeLV, and 82.3% (56/68) with T. gondii. More than half of the PCR-positive cats showed at least one clinical sign suggestive of leishmaniasis (58.8%; 40/68) and dermatological signs were the most frequent ones (45.5%; 31/68). Both tests employing the recombinant antigen rKDDR-plus (i.e., ICT-rKDDR-plus and ELISA-rKDDR-plus) detected more positive cats than the ELISA-CA but presented low overall accuracy. PCR testing using either blood or ocular conjunctival samples detected much more positive cats than serological tests.

DNA-ICM as an adjuvant method applied on oral cytological specimens.

OBJECTIVE: This study aimed to evaluate cytology diagnosis accuracy using adjuvant methods in clinical routine for oral cancer. STUDY DESIGN: This prospective study was conducted on 98 patients with clinically potentially malignant or malignant oral cavity lesions. One oral lesion smear was taken from each patient using a cytobrush before biopsy and stored at PreservCyt Thinprep. Samples were cytologically analyzed, and DNA ploidy measurement was performed on the same slide. The diagnostic methods' accuracy was then calculated. RESULTS: In clinical inspection, 61 patients had suspicious lesions for malignancy, whereas 37 had potentially malignant disorders. Cytology associated with DNA image cytometry presented a sensitivity of 81.2% and specificity of 90.9%. When analyzing lesions located in high-risk sites to oral malignancies individually, cytology associated with DNA image cytometry presented a sensitivity of 88.2%, specificity of 100.0%, accuracy of 90.0%, and Kappa value of 0.77 (CI 95%: 0.48-1.00). CONCLUSIONS: Association between cytology and DNA image cytometry is an objective and non-invasive diagnostic method that demonstrated high sensitivity and specificity in diagnosing malignant epithelial squamous cell transformation in the oral cavity.

Why Are We Still a Worm World in the 2020s? An Overview of Risk Factors and Endemicity for Soil-Transmitted Helminthiasis.

PURPOSE: Soil-transmitted helminthiasis (STH) is one of the most common chronic infections in developing countries associated with poor socioeconomic and sanitary conditions. The main objective of this overview was to evaluate the influence of environmental factors, risk factors related to the host, and control strategies on the prevalence of STH in different regions of the world. METHODS: LILACS, PubMed, Web of Knowledge, Embase, the Cochrane Library, and Clinical Trials (gray literature) databases were used to obtain the systematic reviews published until December 2020. The methodological quality of systematic reviews was assessed using the standard criteria recommended by AMSTAR. RESULTS: The initial results of the bibliographic search identified 1448 articles, of which 66 studies were read in full and 16 met the inclusion criteria. All the reviews included in this overview associated variations in the global prevalence of STH with at least one of the factors related to the environment, host, and/or control strategies. Climate, temperature, soil moisture, precipitation, mass drug administration, lack of access to water, sanitation and hygiene (WASH), and non-use of footwear were considered the main factors associated with the prevalence of STH. Socioeconomic factors, low educational level, and wearing shoes were universal factors related to prevalence, regardless of the location studied. CONCLUSION: The combination of environmental factors, with factors associated with hosts that predispose infection and reinfection of helminths, as well as the adoption of control strategies based on the treatment of target populations instead of the entire population, influenced the prevalence of STH in all the continents evaluated.

Effect of 3-Carene and the Micellar Formulation on Leishmania (Leishmania) amazonensis.

Leishmaniases are neglected tropical diseases caused by obligate intracellular protozoa of the genus Leishmania. The drugs used in treatment have a high financial cost, a long treatment time, high toxicity, and variable efficacy. 3-Carene (3CR) is a hydrocarbon monoterpene that has shown in vitro activity against some Leishmania species; however, it has low water solubility and high volatility. This study aimed to develop Poloxamer 407 micelles capable of delivering 3CR (P407-3CR) to improve antileishmanial activity. The micelles formulated presented nanometric size, medium or low polydispersity, and Newtonian fluid rheological behavior. 3CR and P407-3CR inhibited the growth of L. (L.) amazonensis promastigote with IC50/48h of 488.1 ± 3.7 and 419.9 ±1.5 mM, respectively. Transmission electron microscopy analysis showed that 3CR induces multiple nuclei and kinetoplast phenotypes and the formation of numerous cytosolic invaginations. Additionally, the micelles were not cytotoxic to L929 cells or murine peritoneal macrophages, presenting activity on intracellular amastigotes. P407-3CR micelles (IC50/72 h = 0.7 ± 0.1 mM) increased the monoterpene activity by at least twice (3CR: IC50/72 h >1.5 mM). These results showed that P407 micelles are an effective nanosystem for delivering 3CR and potentiating antileishmanial activity. More studies are needed to evaluate this system as a potential therapeutic option for leishmaniases.

Accuracy Study of Kato-Katz and Helmintex Methods for Diagnosis of Schistosomiasis Mansoni in a Moderate Endemicity Area in Sergipe, Northeastern Brazil.

Schistosomiasis is a neglected tropical disease (NTD) caused by blood flukes from the genus Schistosoma. Brazil hosts the main endemic area in the Americas, where Schistosoma mansoni is the only species causing the disease. Kato-Katz (KK) thick smear is the WHO recommended screening test for populational studies, but there is growing evidence for the sensitivity limitations associated with KK, especially in areas with low parasite loads. Helmintex (HTX) is another highly sensitive egg-detection method, based on the magnetic properties of S. mansoni eggs and their isolation in a magnetic field. The objective of this study is to evaluate both KK and HTX in a moderate endemic locality, Areia Branca, located in the municipality of Pacatuba, in the state of Sergipe in northeastern Brazil. From 234 individual fecal samples, two KK thick smears were prepared and evaluated for each sample. Similarly, 30 g of each fecal sample was processed by HTX protocol. Eggs were detected in 80 (34.18%) residents. Twenty-three (9.83%) samples were positive for eggs (only by KK), and 77 (32.91%) samples showed positive for eggs (only by HTX). Sensitivity, specificity, and accuracy estimates gave values of 28.75%, 100% and 75.64%, respectively, for KK, and 96.25%, 100% and 98.72% respectively, for HTX. The positive predictive value was 100% for both methods, while the negative predictive value was 72.99% for KK and 98.09% for HTX. Overall, HTX presented a superior performance compared to the one sample, two slides KK examination. The study confirms the role of HTX as a reference method for the definition of true-positive samples in comparative accuracy studies and its potential role in the late stages when the certification of schistosomiasis transmission interruption is required. Diagnostic tests are important tools for the elimination of this NTD, besides the effective implementation of safe water, basic sanitation, snail control, and the treatment of infected populations.

Gastrointestinal parasites in free-ranging common marmosets (Callithrix jacchus Linnaeus, 1758) in the state of Sergipe, northeastern Brazil.

Ecological interactions resulting from human interference and environmental changes have implications for human health and the host animals involved in the parasite cycles. Considering the scarcity of surveys of the parasitic fauna of non-human primates in northeastern Brazil, the objective of this study was to investigate the infection by gastrointestinal parasites in free-ranging common marmosets (Callithrix jacchus) in the State of Sergipe. Fecal samples were collected from 52 animals captured in three protected areas. Most of the samples consisted of adult females and 57% were infected with at least one of the 12 identified parasite taxa. The most frequent intestinal parasite was Prosthenorchis sp., followed by Spiruridae, Entamoeba spp. and Strongylida order. The presence of gastrointestinal parasites was not dependent on sex, age or weight, although there was an association with the capture biome.

Thermosensitive system formed by poloxamers containing carvacrol: An effective carrier system against Leishmania amazonensis.

The drugs used in the treatment of leishmaniasis show problems concerning side effects and toxicity. As a result, the search for new actives is necessary, and natural products like carvacrol - 5-isopropyl-2-methylphenol, become a relevant alternative. To enable the use of carvacrol as an antileishmanial agent, thermosensitive hydrogels were developed from poloxamer triblock copolymers 407 (P407) and 188 (P188). Carvacrol-free and carvacrol-containing hydrogels were obtained from P407 alone and from the mixture of P407 and P188. The hydrogels were subjected to Differential scanning calorimetry, Small-angle X-ray scattering, Scanning electron microscopy, and Rheology analysis. The activity of hydrogels and carvacrol isolated against promastigotes and intracellular amastigotes of Leishmania amazonensis and their cytotoxicity in mammalian cells was determined. The sol-gel transition temperature for the binary hydrogel containing carvacrol (HG407/188CA) was 37.04 ± 1.35 °C. HG407/188CA presented lamellar structure at temperatures of 25 °C and 37 °C. HG407/188CA and carvacrol presented IC50 against Leishmania amazonensis promastigotes of 18.68 ± 1.43 µg/mL and 23.83 ± 3.32 µg/mL, respectively, and IC50 against Leishmania amazonensis amastigotes of 35.08 ± 0.75 µg/mL and 29.32 ± 0.21 µg/mL, respectively. HG407/188CA reduced the toxicity of carvacrol in all mammalian cells evaluated, raising the CC50 in murine peritoneal macrophages from 40.23 ± 0.21 µg/mL to 332.6 ± 4.89 µg/mL, obtaining a Selectivity Index (SI) of 9.5 against 1.37 of the isolated carvacrol. HG407/188CA provided higher selectivity of carvacrol for the parasite. Thus, the binary hydrogel obtained may enable the use of carvacrol as a potential antileishmanial agent.

Lippia alba and Lippia gracilis essential oils affect the viability and oviposition of Schistosoma mansoni.

Schistosomiasis is a neglected tropical disease that affects millions of people around the world. Currently, the only drug available for the treatment of this disease is praziquantel, which has low efficacy against immature helminth stages and there are reports of drug resistance. In this study, the chemical composition and the in vitro effect of essential oils (EOs) and major compounds from Lippia gracilis and Lippia alba against schistosomula and adult Schistosoma mansoni worms were evaluated. Adult S. mansoni worms cultured for 8h in the presence of L. gracilis EO (50 and 100 µg/mL) or for 2h with its major compound, carvacrol (100 µg/mL), had a 100% reduction in viability. After interaction with L. alba EO (100µg/mL), there was a reduction of approximately 60% in the viability of adult worms after 24 hours of exposure; citral (50 and 100 µg/mL), its major compound, reduced the viability after 24 hours by more than 75%. Treatment of schistosomula with 100 µg/mL of L. gracilis or L. alba EOs for 6h led to a reduction in parasite viability of 80% and 16% respectively. Both EOs and their major compounds significantly reduced the oviposition of adult worms exposed to a non-lethal concentration (5 µg/mL). In addition, morphological changes such as the destruction of the tegument and disorganization of the reproductive system of male and female worms were visualized. Both EOs showed low cytotoxicity at a concentration of 50 µg/mL. The results encourage further investigation of these plants as a potential source of bioactive compounds against S. mansoni.

O exame parasitológico de fezes frente a campanhas de desparasitação em massa ­ novos desafios e alternativas / The parasitological stool examination in front of mass deworming campaigns - new challenges and alternatives

Com a ampliação e a frequência das campanhas de desparasitação contra os geo-helmintos Ascaris lumbricoides, Trichuris trichiura, ancilostomídeos e Strongyloides stercoralis, ocorreu, como esperado, a redução da prevalência e da morbidade associada a estas parasitoses. Entretanto, alterações no perfil parasitológico das populações com redução dos helmintos e aumento significativo das protozooses intestinais se tornaram evidentes em todo o mundo. Além disso, a redução de carga parasitária tem dificultado o diagnóstico de rotina por meio de técnicas microscópicas de baixa sensibilidade. Neste artigo trazemos atualizações sobre algumas técnicas diagnósticas, como a Técnica de Sedimentação Espontânea em Tubo (SSTT), FLOTAC/Mini-FLOTAC e a otimização do método de Kato-Katz, além de alternativas viáveis para aumentar a sensibilidade dos métodos e tornar o diagnóstico das parasitoses intestinais mais preciso.

With the expansion and increased frequency of deworming against soil-transmitted helminths Ascaris lumbricoides, Trichuris trichiura, hookworms and Strongyloides stercoralis, there was, as expected, a reduction in the prevalence and morbidity associated with these diseases. However, changes in the parasitological profile of populations, with a reduction in helminths and a significant increase in intestinal protozoa, became evident worldwide. In addition, the reduction in the parasitic burden has made routine diagnosis difficult through low-sensitivity microscopic techniques. In this article we bring updates on diagnostic techniques, such as spontaneous sedimentation technique in tube (SSTT), FLOTAC/Mini-FLOTAC and optimization of Kato-Katz technique, as well as viable alternatives to increase the sensitivity of methods and make the diagnosis of intestinal parasites more accurate.

Nisin Induces Cell-Cycle Arrest in Free-Living Amoebae Acanthamoeba castellanii.

PURPOSE: Acanthamoeba spp. are free-living amoebas with worldwide distribution and play an important role as disease-causing agents in humans. Drug inability to completely eradicate these parasites along with their toxic effects suggest urgent need for new antimicrobials. Nisin is a natural antimicrobial peptide produced by Lactococcus lactis. Nisin is also the only bacteriocin approved for use in food preservation. In this work, we analyzed the effect of nisin on the growth of Acanthamoeba castellanii trophozoites. METHODS: A total of 8 × 104 trophozoites were exposed to increasing concentrations of nisin to determine its activity. Changes in cell membrane and cellular cycle of trophozoites were investigated by flow cytometry, and nisin cytotoxicity in mammalian cells was evaluated in L929 cells by MTT method. RESULTS: After 24 h exposure to increasing nisin concentrations, an IC50 of 4493.2 IU mL-1 was obtained for A. castellanii trophozoites. However, after 72 h a recovery in amoebic growth was observed, and it was no longer possible to determine IC50. Flow cytometry analysis showed that nisin has no effect on the membrane integrity. Treatment with nisin induced cell-cycle arrest during G1 and S phases in A. castellanii trophozoites, which recovered their growth after 72 h. CONCLUSION: This is one of the first studies showing the effect of internationally approved nisin against A. castellanii trophozoites. Nisin caused cell-cycle arrest in trophozoites, momentarily interfering with the DNA replication process. The data highlight the amoebostatic activity of nisin, and suggest its use as an adjuvant for the treatment of infections caused by Acanthamoeba spp.

T follicular helper cells: Their development and importance in the context of helminthiasis.

The development of T follicular helper cells (Tfh) is a multifactorial process that occurs in multiple stages. After their activation the Tfh cells interact with the B cells to complete their differentiation. During this process, the Tfh cells begin to express canonical molecules such as the transcription factor B-cell lymphoma 6 protein, the CXC chemokine receptors type 5, and the inducible T-cell costimulator, as well as secreting other molecules such as IL-21. This whole process is regulated positively and negatively by several factors so that the best response is offered in the face of diseases of various origins, among them helminthiasis. In this context, the role of circulating Tfh, IL-4 and IgG subtypes is essential for an effective response against these pathogens. In this review, the migration process and the differentiation of Tfh, the regulation, their cell subtypes and the role of Tfh in the context of helminth infections will be addressed.

Nisin resistance in Gram-positive bacteria and approaches to circumvent resistance for successful therapeutic use.

Antibiotic resistance among bacterial pathogens is one of the most worrying problems in health systems today. To solve this problem, bacteriocins from lactic acid bacteria, especially nisin, have been proposed as an alternative for controlling multidrug-resistant bacteria. Bacteriocins are antimicrobial peptides that have activity mainly against Gram-positive strains. Nisin is one of the most studied bacteriocins and is already approved for use in food preservation. Nisin is still not approved for human clinical use, but many in vitro studies have shown its therapeutic effectiveness, especially for the control of antibiotic-resistant strains. Results from in vitro studies show the emergence of nisin-resistant bacteria after exposure to nisin. Considering that nisin has shown promising results for clinical use, studies to elucidate nisin-resistant mechanisms and the development of approaches to circumvent nisin-resistance are important. Thus, the objectives of this review are to identify the Gram-positive bacterial strains that have shown resistance to nisin, describe their resistance mechanisms and propose ways to overcome the development of nisin-resistance for its successful clinical application.

Trypanocidal Essential Oils: A Review.

Trypanosomiases are diseases caused by parasitic protozoan trypanosomes of the genus Trypanosoma. In humans, this includes Chagas disease and African trypanosomiasis. There are few therapeutic options, and there is low efficacy to clinical treatment. Therefore, the search for new drugs for the trypanosomiasis is urgent. This review describes studies of the trypanocidal properties of essential oils, an important group of natural products widely found in several tropical countries. Seventy-seven plants were selected from literature for the trypanocidal activity of their essential oils. The main chemical constituents and mechanisms of action are also discussed. In vitro and in vivo experimental data show the therapeutic potential of these natural products for the treatment of infections caused by species of Trypanosoma.

Prevalence of Klebsiella pneumoniae carbapenemase - and New Delhi metallo-beta-lactamase-positive K. pneumoniae in Sergipe, Brazil, and combination therapy as a potential treatment option.

INTRODUCTION: Carbapenem-resistant Klebsiella pneumoniae infection lacks treatment options and is associated with prolonged hospital stays and high mortality rates. The production of carbapenemases is one of the most important factors responsible for this multi-resistance phenomenon. METHODS: In the present study, we analyzed the presence of genes encoding carbapenemases in K. pneumoniae isolates circulating in one of the public hospitals in the city of Aracaju, Sergipe, Brazil. We also determined the best combination of drugs that display in vitro antimicrobial synergy. First, 147 carbapenem-resistant K. pneumoniae isolates were validated for the presence of blaKPC, bla GES, bla NDM, bla SPM, bla IMP, bla VIM, and bla OXA-48 genes using multiplex polymerase chain reaction. Thereafter, using two isolates (97 and 102), the role of double and triple combinational drug therapy as a treatment option was analyzed. RESULTS: Seventy-four (50.3%) isolates were positive for bla NDM, eight (5.4%) for bla KPC, and one (1.2%) for both bla NDM and bla KPC. In the synergy tests, double combinations were better than triple combinations. Polymyxin B and amikacin for isolate 97 and polymyxin B coupled with meropenem for isolate 102 showed the best response. CONCLUSIONS: Clinicians in normal practice use multiple drugs to treat infections caused by multi-resistant microorganism; however, in most cases, the benefit of the combinations is unknown. In vitro synergistic tests, such as those described herein, are important as they might help select an appropriate multi-drug antibiotic therapy and a correct dosage, ultimately reducing toxicities and the development of antibiotic resistance.

Prevalence of Klebsiella pneumoniae carbapenemase - and New Delhi metallo-beta-lactamase-positive K. pneumoniae in Sergipe, Brazil, and combination therapy as a potential treatment option

Abstract INTRODUCTION: Carbapenem-resistant Klebsiella pneumoniae infection lacks treatment options and is associated with prolonged hospital stays and high mortality rates. The production of carbapenemases is one of the most important factors responsible for this multi-resistance phenomenon. METHODS: In the present study, we analyzed the presence of genes encoding carbapenemases in K. pneumoniae isolates circulating in one of the public hospitals in the city of Aracaju, Sergipe, Brazil. We also determined the best combination of drugs that display in vitro antimicrobial synergy. First, 147 carbapenem-resistant K. pneumoniae isolates were validated for the presence of blaKPC, bla GES, bla NDM, bla SPM, bla IMP, bla VIM, and bla OXA-48 genes using multiplex polymerase chain reaction. Thereafter, using two isolates (97 and 102), the role of double and triple combinational drug therapy as a treatment option was analyzed. RESULTS: Seventy-four (50.3%) isolates were positive for bla NDM, eight (5.4%) for bla KPC, and one (1.2%) for both bla NDM and bla KPC. In the synergy tests, double combinations were better than triple combinations. Polymyxin B and amikacin for isolate 97 and polymyxin B coupled with meropenem for isolate 102 showed the best response. CONCLUSIONS: Clinicians in normal practice use multiple drugs to treat infections caused by multi-resistant microorganism; however, in most cases, the benefit of the combinations is unknown. In vitro synergistic tests, such as those described herein, are important as they might help select an appropriate multi-drug antibiotic therapy and a correct dosage, ultimately reducing toxicities and the development of antibiotic resistance.

Discrepancy between batches and impact on the sensitivity of point-of-care circulating cathodic antigen tests for Schistosoma mansoni infection.

The Kato-Katz (KK) technique is the mainstay mapping tool for the diagnosis of Schistosoma mansoni infection, despite showing poor sensitivity in cases of low-intensity infections. As an alternative, a rapid point-of-care circulating cathodic antigen diagnostic test (POC-CCA) has been commercially developed that involves a simple urine assay to detect S. mansoni, rather than a stool-based parasitological examination. Although POC-CCA has proven to be a more sensitive test than KK, it is not yet clear how to interpret discordant results between the two tests, particularly for situations in which the KK result is positive and the POC-CCA result is negative. Thus, the objective of this study was to evaluate the degree of diagnostic variability between different POC-CCA batches with respect to results obtained with KK. For this purpose, we collected urine and stool samples of school-aged children from areas of low and moderate endemicity in Brazil, and compared different POC-CCA batches results with those of KK-positive individuals. We found a statistically significant difference between the results obtained from various POC-CCA batches using the same urine samples, regardless of the degree of endemicity and the intensity of infection in positive KK samples. In addition, there was poor agreement between the KK and POC-CCA results in some batches of the rapid test, resulting in false negatives. These findings raise concerns around quality control checks of POC-CCA, especially in light of the high cost and increasing reliance on this new diagnostic method as control programs move towards a goal of elimination.

Elevated prevalence of high-risk HPV in healthy oral mucosa of users and nonusers of drugs in Northeastern Brazil.

Variable rates of HPV infection have been reported in healthy oral mucosa worldwide. The main objective of this study was to detect and genotype HPV infection in users and nonusers of drugs with clinically healthy mucosa from the Northeast Brazil. Samples from 105 patients were amplified using the primers MY09/MY11 and GP5+/GP6+, and genotyping was performed by multiplex-PCR for HPV-6/11, 16 and 18. A total of 81.9% samples were positive. Among drug users, 84.5% presented the virus and 20.4% showed multiple infections. Among non-drug users, 78.7% were positive and 13.5% had multiple infections. Limited information is available on oral HPV in Brazilian population, especially for drug users, and our results showed higher HPV infection rates in both users and nonusers of drugs. More studies and researches focused on drug users including factors like sexual behavior, nutrition and cultural habits are necessary to enhance the comprehension of this relationship, and develop preventive strategies.

Screening of bacterial extracellular xylanase producers with potential for cellulose pulp biobleaching

In this study, two hundred fifty-seven bacterial isolates from a suppressive soil library were screened to study their secretion of alkali-thermostable xylanases for potential use in cellulose pulp biobleaching. Xylanase activity was evaluated in solid and liquid media using xylan as the carbon source. Isolates were initially evaluated for the degradation of xylan in solid media by the congo red test. Selected strains were evaluated in liquid media for enzymatic activity and determination of total protein concentration using a crude protein extract (CPE). An isolate identified as Bacillus species TC-DT13 produced the highest amount of xylanase (1808 U mL-1). The isolate was active and stable at 70°C and pH 9.0, conditions which are necessary for the paper industry. This isolate can grow and produce xylanase in medium containing wheat fiber as a substrate. The CPE of this isolate was used in preliminary testing on cellulose pulp bleaching; enzyme treatment of the pulp resulted in a 5% increase of whiteness.

Mosquitoes of the Caatinga. III. Larval Habitats, Frequency, and Dynamics of Immature and Adult Stages in a Dry Brazilian Forest.

Even though the seasonally dry tropical Caatinga forest is an historically neglected biome, recent studies have enhanced our knowledge of its biodiversity. We investigated larval habitats as well as the frequency and dynamics of immature and adult Culicidae in a conservation unit within the Caatinga in the Brazilian state of Sergipe. We carried out monthly surveys between July 2011 and October 2012 to count both immature (tree holes, bromeliad tanks, ponds, and rock holes and depressions) and adult individuals (Shannon traps baited with light). In total 8,021 individuals representing 32 taxa, eight of which are currently undescribed, were collected. The majority of the specimens collected came from tree holes followed by bromeliads, ponds, and rock depressions. Ponds had the highest species richness in this survey while the bromeliad fauna exhibited high endemicity. We also reveal a correlation between precipitation during the month prior to collection and the abundance of immature individuals in tree holes. Peaks in Haemagogus sp. near spegazzinii and Aedes terrens abundance were observed soon after rain, whereas Culex conservator was abundant during the rainy season in tree holes evidencing a species rotation within this habitat. Although the results of this study contribute to our knowledge regarding the distribution of mosquitoes in Brazilian semiarid region, further taxonomic studies will be required to fully understand the richness and endemism of the Neotropical Culicidae fauna.