Production Of Antimicrobial Substances Research Articles

Production of bacteriocin-like inhibitory substance (BLIS) by Staphylococcus spp. isolates from dogs.

In the present study, 39 canine isolates of Staphylococcus spp. were tested for antimicrobial substance (AMS) production. Seven AMS producers were identified, whose products exhibited a non-acidic character and a proteinaceous nature, therefore being considered bacteriocin-like inhibitory substances (BLIS). The producer strains of BLIS P1, P16 and I3 showed a broad spectrum of antimicrobial activity. Human, veterinary and plant pathogens, such as Listeria monocytogenes, Klebsiella pneumoniae, Staphylococcus spp. and Clavibacter michiganensis, were among the inhibited micro-organisms, suggesting the potential biotechnological application of these peptides. MALDI-TOF mass spectrometry and 16S rDNA sequencing identified the producer strains of BLIS P1, P16 and I3 as Staphylococcus pseudintermedius P1, Staphylococcus schleiferi P16 and Staphylococcus pseudintermedius I3. The plasmid profile of these strains suggests that the BLIS production is linked to biosynthetic genes located on plasmids. PCR analyses revealed that BLIS P1, P16 and I3 are different from 11 staphylococcins already described in the literature and that their genomic DNAs do not carry the most prevalent staphylococcal enterotoxin genes. The highest levels of BLIS production were achieved after 18-24h of growth of the producer strains in TSB medium. Moreover, BLIS P1 and I3 exhibited high resistance to temperature and pH variations, and BLIS P16 maintained 100% of its activity in almost all conditions tested. The characteristics associated with BLIS P1, P16 and I3 described in this work encourage further investigation of these substances, in addition to this study being the first report of BLIS production by a strain of S. schleiferi.

Managing tobacco black shank disease using biochar: direct toxicity and indirect ecological mechanisms.

Black shank disease in tobacco, caused by Phytophthora nicotianae, can lead to yield losses of 30%-50% upon outbreak. Recently, biochar derived from agricultural waste has shown significant potential in controlling soil-borne diseases, though its mechanisms remain unclear. Over a 3-year observation period, we found that the incidence of black shank was significantly lower in plots amended with biochar compared with normal cultivation plots. To investigate the underlying mechanisms, we studied both the direct and indirect effects of biochar on black shank. Direct antifungal assays indicated that biochar reduced the total number of sporangia by 53.91%. Further pot experiments revealed a 62.34% reduction in the P. nicotianae population in the soil following biochar application. Additionally, biochar application led to notable changes in soil physicochemical properties and microbial community composition. Microbial species analysis showed that biochar promoted the aggregation of beneficial microbes such as Sphingomonas, Flavisolibacter, and Mucoromycota. Functional predictions using the PICRUSt 2 software revealed that biochar enhances bacterial functions related to antimicrobial substance synthesis (Tetracycline biosynthesis), detoxification metabolism (D-arginine and D-ornithine metabolism, arginine and proline metabolism), and lipid and fatty acid metabolism (Lipopolysaccharide biosynthesis, fatty acid biosynthesis), while fungal functions showed no significant changes. This suggests that rhizosphere bacteria play a more prominent role in the suppression of black shank by biochar, a finding supported by partial least squares path modeling analysis. Therefore, we hypothesize that biochar not only directly inhibits P. nicotianae growth but also regulates the composition of the rhizosphere microbial community, inducing the production of antimicrobial substances by rhizosphere bacteria, effectively preventing P. nicotianae invasion.IMPORTANCEBlack shank, a global soil-borne fungal disease in tobacco, currently lacks effective control methods. Notably, biochar derived from agricultural waste has shown significant potential in controlling soil-borne diseases. Over a 3-year observation period, we found that plots amended with biochar had a significantly lower incidence of black shank compared with normal cultivation plots. However, the mechanisms of disease suppression remained unclear. Through in vitro antifungal assays and pot experiments, we discovered that tobacco-derived biochar can directly inhibit the growth of the pathogen. Additionally, biochar regulates the composition of the rhizosphere microbial community, inducing rhizosphere bacteria to produce antimicrobial substances, effectively preventing pathogen invasion. This discovery reveals both the direct and indirect mechanisms by which biochar suppresses black shank in tobacco. It provides a scientific basis for developing green control technologies for black shank and offers theoretical support for the application of biochar in managing soil-borne diseases in tobacco cultivation areas.

Methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus produce antimicrobial substances against members of the skin microbiota in children with atopic dermatitis.

Coagulase-negative Staphylococcus (CoNS) species inhibiting Staphylococcus aureus has been described in the skin of atopic dermatitis (AD) patients. This study evaluated whether Staphylococcus spp. from the skin and nares of AD and non-AD children produced antimicrobial substances (AMS). AMS production was screened by an overlay method and tested against NaOH, proteases and 30 indicator strains. Clonality was assessed by pulsed-field gel electrophoresis. Proteinaceous AMS-producers were investigated for autoimmunity by the overlay method and presence of bacteriocin genes by polymerase chain reaction. Two AMS-producers had their genome screened for AMS genes. A methicillin-resistant S. aureus (MRSA) produced proteinaceous AMS that inhibited 51.7% of the staphylococcal indicator strains, and it was active against 60% of the colonies selected from the AD child where it was isolated. On the other hand, 57 (8.8%) CoNS from the nares and skin of AD and non-AD children, most of them S. epidermidis (45.6%), reduced the growth of S. aureus and other CoNS species. Bacteriocin-related genes were detected in the genomes of AMS-producers. AMS production by CoNS inhibited S. aureus and other skin microbiota species from children with AD. Furthermore, an MRSA colonizing a child with AD produced AMS, reinforcing its contribution to dysbiosis and disease severity.

More than the sum of its parts: uncovering emerging effects of microbial interactions in complex communities.

Microbial communities are not only shaped by the diversity of microorganisms and their individual metabolic potential, but also by the vast amount of intra- and interspecies interactions that can occur pairwise interactions among microorganisms, we suggest that more attention should be drawn towards the effects on the entire microbiome that emerge from individual interactions between community members. The production of certain metabolites that can be tied to a specific microbe-microbe interaction might subsequently influence the physicochemical parameters of the habitat, stimulate a change in the trophic network of the community or create new micro-habitats through the formation of biofilms, similar to the production of antimicrobial substances which might negatively affect only one microorganism but cause a ripple effect on the abundance of other community members. Here, we argue that combining established as well as innovative laboratory and computational methods is needed to predict novel interactions and assess their secondary effects. Such efforts will enable future microbiome studies to expand our knowledge on the dynamics of complex microbial communities.

Co-inoculation of the endophytes Bacillus thuringiensis CAPE95 and Paenibacillus polymyxa CAPE238 promotes Tropaeolum majus L. growth and enhances its root bacterial diversity.

Tropaeolum majus L. is a versatile edible plant that is widely explored due to its medicinal properties and as a key element in intercropping systems. Its growth could be improved by the use of biofertilizers that can enhance nutrient uptake by the plant or provide tolerance to different abiotic and biotic stresses. In a previous study, 101 endophytes isolated from T. majus roots showed more than three plant growth-promoting (PGP) features in vitro, such as phosphate mineralization/solubilization, production of siderophores, antimicrobial substances and indole-related compounds, and presence of the nifH gene. To provide sustainable alternatives for biofertilization, the genomes of two promising endophytes-CAPE95 and CAPE238-were sequenced to uncover metabolic pathways related to biofertilization. Greenhouse experiments were conducted with 216 seeds and 60 seedlings, half co-inoculated with the endophytes (treatment) and half inoculated with 1X PBS (control), and the impact of the co-inoculation on the plant's bacteriome was accessed through 16S rRNA gene metabarcoding. The strains CAPE95 and CAPE238 were taxonomically assigned as Bacillus thuringiensis and Paenibacillus polymyxa, respectively. Metabolic pathways related to the enhancement of nutrient availability (nitrogen fixation, sulfate-sulfur assimilation), biosynthesis of phytohormones (indole-3-acetic acid precursors) and antimicrobial substances (bacilysin, paenibacillin) were found in their genomes. The in vivo experiments showed that treated seeds exhibited faster germination, with a 20.3% higher germination index than the control on the eleventh day of the experiment. Additionally, treated seedlings showed significantly higher plant height and leaf diameters (p < 0.05). The bacterial community of the treated plants was significantly different from that of the control plants (p < 0.001) and showed a higher richness and diversity of species (Chao and Shannon indexes, p < 0.001). A higher relative abundance of potential synergistic PGP bacteria was also shown in the bacteriome of the treated plants, such as Lysinibacillus and Geobacter. For the first time, co-inoculation of B. thuringiensis and P. polymyxa was shown to have great potential for application as a biofertilizer to T. majus plants. The bacterial consortium used here could also be explored in other plant species in the future.

Vaginal Lactobacilli Supernatants Protect from Herpes Simplex Virus Type 1 Infection in Cell Culture Models.

A healthy vaginal microbiota hosts Lactobacillus as the most predominant genus. Lactobacilli play a role in human health through the production of diverse antimicrobial substances that can act against human pathogens or modulate the immune system. Previous reports highlighted the ability of vaginal lactobacilli to counteract viruses causing STIs, e.g., HIV-1 and HSV-2. In this report, we analyze the activity of supernatants of vaginal lactobacilli against HSV-1 infection, which is becoming increasingly relevant as a STI. We show that the supernatants of two vaginal Lactobacillus species (i.e., L. crispatus and L. gasseri) were active at neutralizing HSV-1 infection in two different cell lines of human and simian origin. Specifically, we demonstrate that L. crispatus strains are the most effective in antiviral activity, as evidenced by the comparison with a vaginal pathogen taken as reference. The effect was specific and not attributable to the generic toxicity of the supernatants to the cells. Our results pave the way for the development of probiotics to limit the impact of HSV-1 infection on women's health.

De novo genome assembly of a probiotic Lacticaseibacillus rhamnosus ISO20, isolated from raw milk in South Africa.

Lactic acid bacteria are known to exhibit probiotic properties through various mechanisms including production of antimicrobial substances and bile salts tolerance. Here, we report a draft genome sequence of Lacticaseibacillus rhamnosus ISO20, a lactic acid bacterium isolated from raw goat's milk to provide genomic insight into its strategies as probiotic strain.

The Microbial Diversity on the Surface of Smear-Ripened Cheeses and Its Impact on Cheese Quality and Safety.

Smear-ripened cheeses are characterized by a viscous, red-orange surface smear on their rind. It is the complex surface microbiota on the cheese rind that is responsible for the characteristic appearance of this cheese type, but also for the wide range of flavors and textures of the many varieties of smear-ripened cheeses. The surface smear microbiota also represents an important line of defense against the colonization with undesirable microorganisms through various types of interaction, such as competitive exclusion or production of antimicrobial substances. Predominant members of the surface smear microbiota are salt-tolerant yeast and bacteria of the phyla Actinobacteria, Firmicutes, and Proteobacteria. In the past, classical culture-based approaches already shed light on the composition and succession of microorganisms and their individual contribution to the typicity of this cheese type. However, during the last decade, the introduction and application of novel molecular approaches with high-resolution power provided further in-depth analysis and, thus, a much more detailed view of the composition, structure, and diversity of the cheese smear microbiota. This led to abundant novel knowledge, such as the identification of so far unknown community members. Hence, this review is summarizing the current knowledge of the diversity of the surface smear microbiota and its contribution to the quality and safety of smear-ripened cheese. If the succession or composition of the surface-smear microbiota is disturbed, cheese smear defects might occur, which may promote food safety issues. Hence, the discussion of cheese smear defects in the context of an increased understanding of the intricate surface smear ecosystem in this review may not only help in troubleshooting and quality control but also paves the way for innovations that can lead to safer, more consistent, and higher-quality smear-ripened cheeses.

Mild Heat Treatment and Biopreservatives for Artisanal Raw Milk Cheeses: Reducing Microbial Spoilage and Extending Shelf-Life through Thermisation, Plant Extracts and Lactic Acid Bacteria.

The microbial quality of raw milk artisanal cheeses is not always guaranteed due to the possible presence of pathogens in raw milk that can survive during manufacture and maturation. In this work, an overview of the existing information concerning lactic acid bacteria and plant extracts as antimicrobial agents is provided, as well as thermisation as a strategy to avoid pasteurisation and its negative impact on the sensory characteristics of artisanal cheeses. The mechanisms of antimicrobial action, advantages, limitations and, when applicable, relevant commercial applications are discussed. Plant extracts and lactic acid bacteria appear to be effective approaches to reduce microbial contamination in artisanal raw milk cheeses as a result of their constituents (for example, phenolic compounds in plant extracts), production of antimicrobial substances (such as organic acids and bacteriocins, in the case of lactic acid bacteria), or other mechanisms and their combinations. Thermisation was also confirmed as an effective heat inactivation strategy, causing the impairment of cellular structures and functions. This review also provides insight into the potential constraints of each of the approaches, hence pointing towards the direction of future research.

Isolation and identification of Bacillus species from soil and assessment of antimicrobial properties

The emergence of multi drug resistant pathogens such as Methicillin resistant Staphylococcus aureus (MRSA) has become a threat to public health. Thus, the development of new antibiotics has become a global concern. Many scientists are attracted towards discovery of new antimicrobial agents from microbial sources. The aim of this study is to isolate potential Bacillus species from soil for the production of antimicrobial substance. During the study, 20 soil samples were collected from various areas of Kathmandu valley. A total of 70 Bacillus isolates were identified by morphological and biochemical characteristics. Altogether 39 isolates were able to produce antibacterial extract when it was grown in Trypticase soya broth (TSB) at 37°C for 48 h. The antimicrobial activity was tested against test organisms like Escherichia coli, Klebsiella pneumoniae, Salmonella, Pseudomonas, Staphylococcus aureus and Candida by Agar well diffusion method. All of the extracts showed zone of inhibition against E. coli except 6 extracts (E39, E43, E36, E25, E45 and E46). The highest zone of inhibition was shown by extract B68 with 11 mm. Only one extract (E62) was able to inhibit the growth of Pseudomonas. The extract from Bacillus isolate (E35) showed highest zone of inhibition against S. aureus (6mm). The protein nature of the extracts was determined by Biuret and Ninhydrin tests. The extracts were relatively stable to heat treatment and unstable to surfactants like 70% methanol, 2-propanol and ethylacetate. The study revealed that soil is a good source for the potential antimicrobial producer bacteria.

Aflatoxin B1 damaged structural barrier through Keap1a/Nrf2/ MLCK signaling pathways and immune barrier through NF-κB/ TOR signaling pathways in gill of grass carp (Ctenopharyngodon idella)

Aquafeeds are susceptible to contamination caused by aflatoxin B1 (AFB1). The gill of fish is an important respiratory organ. However, few studies have investigated the effects of dietary AFB1 exposure on gill. This study aimed to discuss the effects of AFB1 on the structural and immune barrier of grass carp gill. Dietary AFB1 increased reactive oxygen species (ROS) levels, protein carbonyl (PC) and malondialdehyde (MDA) contents, which consequently caused oxidative damage. In contrast, dietary AFB1 decreased antioxidant enzymes activities, relative genes expression (except MnSOD) and the contents of glutathione (GSH) (P < 0.05), which are partly regulated by NF-E2-related factor 2 (Nrf2/Keap1a). Moreover, dietary AFB1 caused DNA fragmentation. The relative genes of apoptosis (except Bcl-2, McL-1 and IAP) were significantly upregulated (P < 0.05), and apoptosis was likely upregulated through p38 mitogen-activated protein kinase (p38MAPK). The relative expressions of genes associated with tight junction complexes (TJs) (except ZO-1 and claudin-12) were significantly decreased (P < 0.05), and TJs were likely regulated by myosin light chain kinase (MLCK). Overall, dietary AFB1 disrupted the structural barrier of gill. Furthermore, AFB1 increased gill sensitivity to F. columnare, increased Columnaris disease and decreased the production of antimicrobial substances (P < 0.05) in grass carp gill, and upregulated the expression of genes involved with pro-inflammatory factors (except TNF-α and IL-8) and the pro-inflammatory response partly attributed to the regulation by nuclear factor κB (NF-κB). Meanwhile, the anti-inflammatory factors were downregulated (P < 0.05) in grass carp gill after challenge with F. columnare, which was partly attributed to the target of rapamycin (TOR). These results suggested that AFB1 aggravated the disruption of the immune barrier of grass carp gill after being challenge with F. columnare. Finally, the upper limit of safety of AFB1 for grass carp, based on Columnaris disease, was 31.10 μg/kg diet.

Modern Aspects of the Use of Probiotic and Prebiotic Products in Urological Practice (Literature review)

The article discusses probiotic, prebiotic and synbiotic products, their types, benefits and possibilities of use in urological practice. The effectiveness and safety of use is shown based on the analysis of various clinical studies. Research results show that probiotics have a potentially positive effect on the host’s body in several different ways: 1) antagonism through the production of antimicrobial substances; 2) competition with pathogens for adhesion to the epithelium and for nutrients; 3) immunomodulation. Thanks to such mechanisms, the intestinal microbiota acts as a barrier to pathogens. Probiotic organisms are critical for maintaining the balance of the human gut microbiota and have high therapeutic potential. Some drugs of the group of probiotics contain only one type of microorganisms of normal microflora, other drugs contain several at once. Depending on the type of microorganisms contained in this or that probiotic, its therapeutic activity and scope of application are determined. Prebiotics can be used as an alternative to probiotics or as additional support for them. The mechanism of action of the prebiotic includes an effect on the intestinal flora by increasing the number of beneficial anaerobic bacteria and reducing the population of potentially pathogenic microorganisms. The effects of prebiotics include potentiation of the growth of normal intestinal biota, stimulation of mucosal immune mechanisms, and the possibility of influencing non-immune mechanisms through antagonism with potential intestinal pathogens. The experience of using traditional probiotics, with the introduction of a sufficient amount of a new form of influence on the intestinal microflora – prebiotics, indicates a significant increase in the therapeutic effectiveness of such combinations (prebiotic + probiotic), which as a result increases the chance of complete elimination of the microbial agent, and also accelerates the process of restoring normal intestinal function . Synbiotics are products that contain both probiotics and prebiotics, combining their pharmacological effects. One of the most well-known pharmacological groups capable of a positive effect on the intestinal biocenosis is natural enterosorbents. The appointment of an enterosorbent in the period after the use of antibiotic therapy in cases of treatment of urological infections should consist in choosing a drug containing a balanced composition of components aimed at sorption, as well as optimizing the growth of normal intestinal biota. The development of biotherapeutic formulas containing both appropriate microbial strains and synergistic prebiotics can lead to increased therapeutic effect in the treatment of patients with urological pathology.

Antimicrobial activity of Streptomyces spp. sponge-associated isolated from Samalona Island of South Sulawesi, Indonesia

Abstract. Rante H, Alam G, Usmar, Zahra S, Kurniawati A, Ali A. 2022. Antimicrobial activity of Streptomyces spp. sponge-associated isolated from Samalona Island of South Sulawesi, Indonesia. Biodiversitas 23: 1392-1398. The resistance case of infectious diseases increases annually, while the necessity of antibiotics as a drug choice for therapy most important is needed. One of the efforts to overcome these problems is an investigation of new antibiotic sources, namely marine organisms. Actinomycetes are microbes well known as more antibiotic-producing than fungi and bacteria. This study aims to the identification of marine actinomycetes isolated from sponge samples in Samalona Island, South Sulawesi, Indonesia. The antimicrobial activity was evaluated against multi-drug resistant (MDR) Staphylococcus aureus, Escherichia coli, and Candida albicans. Isolation was carried out using SCA (Starch Casein Agar) medium by the pour plate method. The selected isolates were designated as SML10h and SML10a. The isolates SML 10h and SML 10a were recovered from sponges Haliclona sp. and Aplysina sp., respectively. The production of antimicrobial substances was performed by fermentation of isolates in SNB (Starch Nitrate Broth) medium for 14 days. The antimicrobial activity was shown by the ethyl acetate extract with 2 mg/20 ?L concentration against all test microbes. Phylogenetic analysis of the 16S rRNA gene sequences revealed that the similarity of SML 10a was most closely related to Streptomyces geysiriensis (98%).

Taxonomic and Functional Diversity of Rhizosphere Microbiome Recruited From Compost Synergistically Determined by Plant Species and Compost.

Compost is frequently served as the first reservoir for plants to recruit rhizosphere microbiome when used as growing substrate in the seedling nursery. In the present study, recruitment of rhizosphere microbiome from two composts by tomato, pepper, or maize was addressed by shotgun metagenomics and 16S rRNA amplicon sequencing. The 16S rRNA amplicon sequencing analysis showed that 41% of variation in the rhizosphere bacterial community was explained by compost, in contrast to 23% by plant species. Proteobacterial genera were commonly recruited by all three plant species with specific selections for Ralstonia by tomato and Enterobacteria by maize. These findings were confirmed by analysis of 16S rRNA retrieved from the shotgun metagenomics library. Approximately 70% of functional gene clusters differed more than sevenfold in abundance between rhizosphere and compost. Functional groups associated with the sensing and up-taking of C3 and C4 carboxylic acids, amino acids, monosaccharide, production of antimicrobial substances, and antibiotic resistance were over-represented in the rhizosphere. In summary, compost and plant species synergistically shaped the composition of the rhizosphere microbiome and selected for functional traits associated with the competition on root exudates.

The Impact of Bacteria of the Genus Bacillus upon the Biodamage/Biodegradation of Some Metals and Extensively Used Petroleum-Based Plastics

This paper tackles bacteria of the genus Bacillus as both biodamaging/biodegrading and biocontrolling agents. The article addresses the said bacteria’s ability to form biofilms and corrosive, antimicrobial and antibiofilm proactive compounds, primarily, siderophores. Their role depends on the species, microorganism strain, production of antimicrobial substances, biofilm formation, and the type of damaged material. The bacteria under analysis have demonstrated the ability to cause as well as inhibit biodamage. The involvement of bacteria of the genus Bacillus in microbiologically influenced corrosion processes is determined by the production of corrosive metabolites and the impact of certain bioelectrochemical mechanisms. Lipopeptides generated by Bacillus subtilis (surfactin, iturin and fengycin) are capable of modifying surfaces’ hydrophobic properties and impacting the microbes’ adhesion to surfaces. Produced by Bacillus velezensis, the siderophore bacillibactin at a high concentration is capable of inhibiting the formation of bacterial biofilms, thus slowing down the degradation of materials. Further study of siderophores as green inhibitors of microbiologically influenced corrosion may be promising as the said compounds possess antibiofilm-forming properties and high-intensity inhibitory capabilities.

Characterization and Screening of Lactic Acid Bacteria (LAB) and Yeast from Fermented Sorghum and Maize Products for use as Starter Culture

This study focused on the isolation, Characterization and screening of lactic acid bacteria and yeast for use as starter culture in order to eradicate the problem of excessive microbial contamination and the presence of mycotoxins.&#x0D; Lactobacillus plantarum and Saccharomyces cerevisiae were the predominant microorganisms isolated from the samples collected. The isolates were screened for their ability to produce enzymes and metabolites. Lactic acid bacteria produce a variety of antimicrobial compounds such as lactic acid, hydrogen peroxide, diacetyl on them as a natural competitive means to overcome other microorganism sharing the same niche. They were also screened for their ability to withstand some physiological stress like acid tolerance, temperature, salt concentration and antibacterial activity; the isolates produced significant values of enzymes and, antimicrobial metabolites. The antimicrobial activity of Lactobacillus plantarum is mainly attributed to the low pH due to Lactic acid production. The antimicrobial activity of the Saccharomyces cerevisiae appears to be mainly due to the competition with the other microorganisms. In addition, depletion of Oxygen and production of CO2, competition for nutrients and the production of antimicrobial substances could have been responsible for the overall antimicrobial activity of both cultures. According to the results obtained, both lactic acid bacteria and yeast proved to be a good source of starter culture.

Isolation and properties of antimicrobial substance produced by Sinhorhizobium melilloti from root nodules of Medicago sativa

The symbiotic association of alfalfa (Medigaco sativa) with Sinorhizobium melilloti contributes to the production of inoculum to improve plant growth and increase yield. The competitiveness of the introduced strains is a very important factor in the performance of an inoculum which is based on the use of rhizobial strains. This competitiveness is due to the production of anti-microbial substances, among them, bacteriocines. In this study, the totals of 30 rhizobial strains were isolated from M. sativa nodules sampled from sa-line soils of Algeria. Twenty strains were nodulated the host plant M. sativa. The antimicrobial activity producing strains SW16 and SW15 were identified as Sinorhizobium melliloti based on 16S rRNA sequance analysis. Partial puri-fication of this inhibitorys substances by ammonium sulfate were precipitat-ed with 75% saturation. These antimicrobial activitys showed the maximum activity against the strain SW10 estimated at 1800 with the strain SW16 and 2500 AU/ml for the strain SW15. The physicochemical properties of these antimicrobial activitys reveals thier thermoresistant nature and sensitive to protease, but theire were resistant to a wide range of pH and also at differ-ent concentrations of Nacl. This inhibitory agent display primary metabolite kinetics as its maximal production was detected in the growth phase. Antimi-crobial substances produced by sinorhizobium mielilloti SW15 and SW16 exhibited inhibitory activity against the phytopathogen (Aspergillus sp., Fusarium sp., Cladosporium sp. and Alternaria altterna).

Antimicrobial activity in cultures of endophytic fungi isolated from Talinum triangulare

. Endophytic fungi colonize the interior of plants without causing damage and act in symbiosis with their host. They are also potential sources of compounds with potential applications in industry, agriculture, and medicine, Thus, this study aimed to isolate and identify the endophytic fungi medicinal plant Talinum triangulare and evaluate its potential for the production of antimicrobial substances using the disk diffusion technique and testing in liquid medium front of Staphylococcus aureus ATCC SA 6538, Pseudomonas aeruginosa ATCC PA 0030, and Corynebacterium diphtheria ATCC 27012. Corynebacterium diphtheria was isolated from 3 fungi of the genus Trichoderma and Penicillium, with only the genus Trichoderma fungi showing antimicrobial activity.

Kocuria spp. in Foods: Biotechnological Uses and Risks for Food Safety

Background and objective: Bacteria of the Genus Kocuria are found in several environments and their isolation from foods has recently increased due to more precise identification protocols using molecular and instrumental techniques. This review describes biotechnological properties and food-linked aspects of these bacteria, which are closely associated with clinical cases. Results and conclusion: Kocuria spp. are capable of production of various enzymes, being potentially used in environmental treatment processes and clinics and production of antimicrobial substances. Furthermore, these bacteria show desirable enzymatic activities in foods such as production of catalases and proteases. Beneficial interactions with other microorganisms have been reported on increased production of enzymes and volatile compounds in foods. However, there are concerns about the bacteria, including their biofilm production, which generates technological and safety problems. The bacterial resistance to antimicrobials is another concern since isolates of this genus are often resistant or multi-resistant to antimicrobials, which increases the risk of gene transfer to pathogens of foods.

Biological control in the germination of seeds from two species native of the Cerrado region.

Microorganisms have been efficiently used for the biological control of phytopathogens through the production of antimicrobial substances. However, the objectives of this work were: to study the germination of Butia purpurascens Glassman and Butia archeri Glassman seeds in different substrates, to select and identify the endophytic and rhizospheric bacterial isolates of B. purpurascens and B. archeri, and to perform antibiosis tests based on the isolated microorganisms of these tree species. No difference was found between the cultivation substrates for the percentages of germination, hard seeds, and fungal contamination in the B. purpurascens seeds. The Bacillus subtilis isolated showed the best capacity for suppressing the growth of the two deteriorative fungi tested in B. purpurascens seeds. No difference was found for inhibition of the growth of Aspergillus niger fungus (deteriorative fungus of B. archeri seeds) between the microorganisms with Bacillus sp. and Brevibacillus brevis compared to the control. In the microbiolization of B. purpurascens and B. archeri seeds performed with microbiological solutions produced from the endophytic and rhizospheric strains of Bacillus sp., no differences were observed in the percentages of germination and contamination by fungi. For B. archeri seeds, there was contamination by fungi and bacteria after one day of cultivation, primarily in the regions with lesions caused by the extraction and scarification process.