Production Of Antimicrobial Compounds Research Articles

Uncovering the potential of actinobacterium BLH 1-22 isolated from marine sediment as a producer of antibiotics

Actinobacteria have been known as producers of many bioactive compounds. The present study examines ten marine Actinobacterial isolates, aiming to investigate their potential as producers of antimicrobial compounds. The secondary metabolites were extracted from these Actinobacteria using ethyl acetate, and the crude extracts were tested for their bioactivity against Escherichia coli, Bacillus subtilis, and Micrococcus luteus. The antibacterial screening showed that the crude extracts of these Actinobacteria inhibit the growth of indicator strains. The extracts of isolate BLH 1-22 were further analysed using high-performance liquid chromatography (HPLC), which showed potential compounds with peak and retention time similar to the antibiotic standards (i.e., erythromycin, ampicillin, tetracycline, and penicillin). In addition to the HPLC profile, molecular identification showed that the isolate BLH 1-22 was similar to Micromonospora chalcea (99.6%). Further genome characterization of the strain, as well as purification and fractionation of the metabolite extracts, are important to obtain a comprehensive study on the potential of isolate BLH 1-22 as antibiotic compound producers. This study reported the potential of Micromonospora BLH 1-22 isolated from marine sediment. Hence, it also highlighted the potential of Actinobacteria isolated from Indonesian environments for bioprospecting studies.

Biostimulation of Bacteria in Liquid Culture for Identification of New Antimicrobial Compounds.

We hypothesized that environmental microbiomes contain a wide range of bacteria that produce yet uncharacterized antimicrobial compounds (AMCs) that can potentially be used to control pathogens. Over 600 bacterial strains were isolated from soil and food compost samples, and 68 biocontrol bacteria with antimicrobial activity were chosen for further studies based on inhibition assays against a wide range of food and plant pathogens. For further characterization of the bioactive compounds, a new method was established that used living pathogens in a liquid culture to stimulate bacteria to produce high amounts of AMCs in bacterial supernatants. A peptide gel electrophoresis microbial inhibition assay was used to concurrently achieve size separation of the antimicrobial peptides. Fifteen potential bioactive peptides were then further characterized by tandem MS, revealing cold-shock proteins and 50S ribosomal proteins. To identify non-peptidic AMCs, bacterial supernatants were analyzed by HPLC followed by GC/MS. Among the 14 identified bioactive compounds, 3-isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione and 2-acetyl-3-methyl-octahydropyrrolo[1,2-a]piperazine-1,4-dione were identified as new AMCs. Our work suggests that antimicrobial compound production in microbes is enhanced when faced with a threat from other microorganisms, and that this approach can rapidly lead to the development of new antimicrobials with the potential for upscaling.

Anti-microbial Activities of <em>Pseudomonas</em> Metabolites Methanolic Extracts against Different MDR Bacterial Pathogens

Background: A Multiple drug resistance (MDR) in pathogenic bacteria has become a significant public health issue for treatment. Among bacteria, Pseudomonas is another important genus except Streptomyces and Bacillus in production of antimicrobial compounds. The current study aim to to determine the antibacterial activity and preliminary characterization of antibacterial compounds produced by Pseudomonas species such as BB1D11, BN2D41, TG1D11, TR1D41, LH1D11 and TN1D41. Method: The antibacterial activity was checked by using bio autography method as well as agar well diffusion method, against four multiple drug resistant bacteria including three Gram negative bacteria (E.coli, Acinetobacter and Pseudomonas) and one Gram positive bacterium (Methicillin Resistant Staphylococcus aureus). Isolation test showed good activity against all the four MDR bacteria, by producing clear zone of diameter from 2mm up to 20mm. Optimum temperature for growth and antibiotic production of Pseudomonas BB1D11, BN2D41, TG1D11, TR1D41, LH1D11 and TN1D41 was 37C0. It produces more metabolites when subjected to shaking incubation. In thin layer chromatography, the extracts were repeatedly inserted on a silica gel coated plate, which was run in mobile phase. Normal HPLC was perform to reveal the presence of antibacterial compounds. Results: By well diffusion assay a zone of inhibition range from 2-18 mm of diameter against different test bacteria. The components were separated, resulting in the formation of bands with different colors, each showing a different compounds. Biological screening was performed by bio autography, metabolites showed a significant activity at retention factor of 0.89. While HPLC at retention time 2.50-2.90 showed presence of significant antibacterial compounds. Conclusion: Pseudomonas BB1D11, BN2D41, TG1D11, TR1D41, LH1D11 and TN1D41 showed promising anti-microbial activity against different MDR bacteria. It is concluded that HPLC revealed the presence of DAPG at retention time 2.90 which inhibit the growth of MDR bacterial strains.

Antimicrobial compound production by pigment producing endophytic bacterium (Burkholderia sp. GBPI_TWL) isolated from Taxus wallichiana Zucc.

Antimicrobial compound production by pigment producing endophytic bacterium (Burkholderia sp. GBPI_TWL) isolated from Taxus wallichiana Zucc.

The antioxidant activity of Lactic acid bacteria and probiotics: a review

Probiotics and Lactic Acid Bacteria play important roles such as the production of antimicrobial compounds and other metabolites. So they have positive effects on human health. When reactive oxygen species generated in excess or cellular defenses are deficient, biomolecules can be damaged by the oxidative stress process. Various studies have shown that the best way to protect the human body from the effects of oxidation reactions is to avoid them, which can be accomplished by using antioxidants. Due to the damages of synthetic antioxidants, their usage has been discussed. Nowadays natural antioxidants derived from bio-resources have recently gained a lot of attention as a potential replacement for synthetic antioxidants. Probiotic bacteria are thought to defend against oxidative stress by restoring the gut microbiota, according to hypothesis of some scientists. This type of microorganisms indicated their antioxidant activity by producing and increasing antioxidant enzymes, production of secondary metabolites, small hydrolyzed peptides in food, resistance to the presence of hydrogen peroxide, and production of intracellular and extracellular compounds such as Exopolysaccharides. Also, they have shown their positive effect on in vivo models. In conclusion, according to the results of studies, lactic acid bacteria and probiotics are significant sources of natural antioxidants. Therefore, they have important research value and market development potential. Also, it should be noted that the mechanism of antioxidant activity of this group of microorganisms has not been fully investigated, this requires further research.

Mannan Oligosaccharides Application: Multipath Restriction From Aeromonas hydrophila Infection in the Skin Barrier of Grass Carp (Ctenopharyngodon idella).

The objective of this study was to evaluate the efficacy of dietary Mannan oligosaccharides (MOS) supplementation on skin barrier function and the mechanism of on-growing grass carp (Ctenopharyngodon idella). Five hundred forty grass carp were fed for 60 days from the growing stage with six different levels of MOS diets (0, 200, 400, 600, 800, and 1,000 mg kg-1). At the end of the growth trial, the 14-day Aeromonas hydrophila challenge experiment has proceeded. The obtained data indicate that MOS could (1) decline skin lesion morbidity after being challenged by the pathogenic bacteria; (2) maintain physical barrier function via improving antioxidant ability, inhibiting excessive apoptosis, and strengthening the tight junction between the epithelial cell and the related signaling pathway (Nrf2/Keap1, p38MAPK, and MLCK); and (3) regulate immune barrier function by modulating the production of antimicrobial compound and expression of involved cytokines and the related signaling pathway (TOR and NFκB). Finally, we concluded that MOS supplementation reinforced the disease resistance and protected the fish skin barrier function from Aeromonas hydrophila infection.

Characterization of active lead molecules from Lissocarinus orbicularis with potential antimicrobial resistance inhibition properties

BackgroundMarine organisms are the potential contributors of novel bioactive molecules. Nevertheless, their biodiversity and the versatility of bioactive metabolites have not been fully explored. Hence, the aim of the present study was to investigate the potentials of gut associated bacteria from a marine crab for the production of novel antibacterial compound. MethodsAerobic gut autochthonous bacteria isolated from marine crab (Lissocarinus orbicularis) collected from Pazhayar coastal area in Nagapattinam district of Tamil Nadu, India were screened for antibacterial activity. Optimization for bacterial growth and antimicrobial compound production, extraction, purification and characterization were studied. ResultsIn the present study, eight morphologically distinct colonies of L. orbicularis gut associated aerobic bacterial isolates (Iso1-Iso8) on Zobell marine agar plate were selected. Isolates were screened for antimicrobial activity against human bacterial pathogens such as Salmonella paratyphi, Vibrio cholera, Vibrio parahaemolyticus, Aeromonas hydrophila and Listeria monocytogenes. On the basis of screening results, isolate 5 (Iso5) was selected as the most potential strain and identified as Paenibacillus polymyxa using biochemical and 16S rRNA sequencing methods. The sequence data was submitted to NCBI (Gene bank Accession No: MK583465). Optimization of P. polymyxa for growth and antimicrobial compound production revealed incubation period (36 h), agitation (150 rpm), pH 8.0, 35 °C, 2.5% salinity, 2% glucose and 1% yeast extract as carbon and nitrogen sources respectively were the ideal conditions and mass culture was done with these parameters. Antimicrobial compound from the cell free supernatant of mass culture medium was extracted using ethanol. The lowest minimum inhibitory concentration (MIC) of 16 μg/ml was observed against of both V. parahaemolyticus and V. cholerae. GC–MS analysis of the active ethanol fraction showed the presence of different components such as dodecane (96.72%), Tridecane (1.69%), Undecane, 2,6-dimethyl- (1.69%), Tetradecane (1.12%) and Dodecane, 2,6,11-trimethyl- (1.12%). ConclusionThe present study showed that the gut associated autochthonous bacteria of marine crabs are one of the potential sources of antibacterial compound. However, further studies are needed for the identification of the antimicrobial compound.

Effect of Novel Bacteriocinogenic Lactobacillus fermentum BZ532 on Microbiological Shelf-Life and Physicochemical and Organoleptic Properties of Fresh Home-Made Bozai.

Bacteriocinogenic Lactobacillus fermentum BZ532 with novel bacteriocin LF-BZ532 was originally isolated from Chinese cereal fermented drink, showing an antimicrobial characteristic during fermentation. This study aimed to explore the in situ antimicrobial activities of L. fermentum BZ532 and co-culturing investigation against key food pathogens, i.e., Staphylococcus aureus and Escherichia coli K-12, was conducted during fresh bozai production. The growth of spoilage bacteria was suppressed and bacterial count was reduced to a significantly low level during 48 h of co-cultures. In situ production of antimicrobial compounds expressed positive activity against S. aureus and E. coli K-12, but negative acitivity against Salmonella sp. D104. The total viable count of bozai BZ-Lf (bozai fermented with BZ532 strain) had a comparatively lower viable count than bozai BZ-C (bozai as an experimental control without BZ532) during storage of 7 days. Titratable acidity of bozai treatments (BZ-C, BZ-Lf) was increased, while pH declined accordingly during storage of 7 days. The organoleptic quality of bozai BZ-C had low sensorial scores as compared with BZ-Lf during storage. In comparison with naturally fermented bozai (BZ-C), L. fermentum BZ532 (BZ-Lf) could significantly reduce the microbial spoilage and extend the shelf-life based on microbiological examination. Conclusively, L. fermentum BZ532 can be used as a bio-protective culture for improving the safety of bozai.

Identification of Burkholderia and Penicillium isolates from kauri (Agathis australis) soils that inhibit the mycelial growth of Phytophthora agathidicida

Phytophthora agathidicida is a highly virulent pathogen of kauri (Agathis australis) and the causal agent of dieback disease in New Zealand’s kauri forests. This study aimed to identify microbial isolates isolated from kauri forest soils that inhibited the growth of P. agathidicida. Three different forms of in vitro bioassays were used to assess the inhibition of each isolate on the mycelial growth of P. agathidicida. Furthermore, head space (HS) solid-phase micro-extraction coupled with gas chromatography-mass spectrometry (SPME-GCMS) was performed to identify if the microbial isolates emitted volatile organic compounds (VOCs), which may be contributing to inhibition. This research identified several bacterial isolates belonging to the genus Burkholderia that inhibited the mycelial growth of P. agathidicida. Furthermore, several VOCs produced by these isolates were putatively identified, which may be responsible for the inhibition observed in the bioassays. Several isolates of Penicillium were identified that inhibit Phytophthora agathidicida, with the culture filtrate of one isolate being found to strongly inhibit P. agathidicida mycelial growth. These isolates of Burkholderia and Penicillium appear to exhibit multiple modes of antagonism against P. agathidicida, including microbial competition and the production of diffusible and volatile anti-microbial compounds. Although further research is needed to better define their mechanisms of inhibition, these findings have identified candidate microbial antagonists of P. agathidicida.

Biocontrol Agents Reduce Progression and Mycotoxin Production of Fusarium graminearum in Spikelets and Straws of Wheat.

The aim of this study was to evaluate the interactions between wheat plant (spikelets and straws), a strain of mycotoxigenic pathogen Fusarium graminearum and commercial biocontrol agents (BCAs). The ability of BCAs to colonize plant tissue and inhibit the pathogen or its toxin production was observed throughout two phases of the life cycle of pathogens in natural conditions (colonization and survival). All evaluated BCAs showed effective reduction capacities of pathogenic traits. During establishment and the expansion stage, BCAs provoked an external growth reduction of F. graminearum (77–93% over the whole kinetic studied) and mycotoxin production (98–100% over the whole kinetic studied). Internal growth of pathogen was assessed with digital droplet polymerase chain reaction (ddPCR) and showed a very strong reduction in the colonization of the internal tissues of the spikelet due to the presence of BCAs (98% on average). During the survival stage, BCAs prevented the formation of conservation perithecia of the pathogen on wheat straw (between 88 and 98% of perithecia number reduction) and showed contrasting actions on the ascospores they contain, or perithecia production (−95% on average) during survival form. The mechanisms involved in these different interactions between F. graminearum and BCAs on plant matrices at different stages of the pathogen’s life cycle were based on a reduction of toxins, nutritional and/or spatial competition, or production of anti-microbial compounds.

Signaling Pathways and Downstream Effectors of Host Innate Immunity in Plants.

Phytopathogens, such as biotrophs, hemibiotrophs and necrotrophs, pose serious stress on the development of their host plants, compromising their yields. Plants are in constant interaction with such phytopathogens and hence are vulnerable to their attack. In order to counter these attacks, plants need to develop immunity against them. Consequently, plants have developed strategies of recognizing and countering pathogenesis through pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). Pathogen perception and surveillance is mediated through receptor proteins that trigger signal transduction, initiated in the cytoplasm or at the plasma membrane (PM) surfaces. Plant hosts possess microbe-associated molecular patterns (P/MAMPs), which trigger a complex set of mechanisms through the pattern recognition receptors (PRRs) and resistance (R) genes. These interactions lead to the stimulation of cytoplasmic kinases by many phosphorylating proteins that may also be transcription factors. Furthermore, phytohormones, such as salicylic acid, jasmonic acid and ethylene, are also effective in triggering defense responses. Closure of stomata, limiting the transfer of nutrients through apoplast and symplastic movements, production of antimicrobial compounds, programmed cell death (PCD) are some of the primary defense-related mechanisms. The current article highlights the molecular processes involved in plant innate immunity (PII) and discusses the most recent and plausible scientific interventions that could be useful in augmenting PII.

Preparation and Functional Properties of Synbiotic Yogurt Fermented with Lactobacillus brevis PML1 Derived from a Fermented Cereal-Dairy Product.

Nowadays, production of functional foods has become very essential. Inulin is one of the most functional hydrocolloid compounds used in such products. In the present study, the production of a synbiotic yogurt containing 1, 2.5, and 5% (w/v) inulin has been investigated. The yogurt was fermented with Lactobacillus brevis PML1 derived from Tarkhineh, an Iranian cereal-dairy fermented food. Furthermore, the physicochemical properties, antioxidant activity, sensory attributes, and microbial viability properties were investigated on the 0th, 7th, and 14th days of storage after fermentation. The viable cells of L. brevis PML1 reached 108 CFU/g, and the product resisted to simulated digestive juices. Moreover, the synbiotic yogurt impressively increased the production of antimicrobial compounds and had the most profound antimicrobial effect on S. typhimurium. The physiochemical properties were in the normal range, and the fat content of the synbiotic yogurt was reduced remarkably. The antioxidant capacity of the fermented yogurt was significantly increased (p < 0.05), which was equal to those of DPPH (69.18 ± 1.00%) and BHA (89.16 ± 2.00%). The viability of L. brevis PML1 was increased during storage. Sensory analysis showed that there were significant differences in terms of the impressive parameters between the samples and the control (p < 0.05). Addition of 2.5% inulin not only improved the physical properties but also retained the viability of the probiotic after 14 days of storage, in addition to the viability of L. brevis with a viability count above 6 log CFU/g in the yogurt. Therefore, a novel synbiotic product containing L. brevis PML1, which can exert the desired properties, can be used as a suitable carrier for the delivery of the probiotic strain, exerting its beneficial health effects.

Identification of Potential Probiotics Producing Bacteriocins Active against Listeria monocytogenes by a Combination of Screening Tools.

Listeria monocytogenes is an important food-borne pathogen and a serious concern to food industries. Bacteriocins are antimicrobial peptides produced naturally by a wide range of bacteria mostly belonging to the group of lactic acid bacteria (LAB), which also comprises many strains used as starter cultures or probiotic supplements. Consequently, multifunctional strains that produce bacteriocins are an attractive approach to combine a green-label approach for food preservation with an important probiotic trait. Here, a collection of bacterial isolates from raw cow’s milk was typed by 16S rRNA gene sequencing and MALDI-Biotyping and supernatants were screened for the production of antimicrobial compounds. Screening was performed with live Listeria monocytogenes biosensors using a growth-dependent assay and pHluorin, a pH-dependent protein reporting membrane damage. Purification by cation exchange chromatography and further investigation of the active compounds in supernatants of two isolates belonging to the species Pediococcus acidilactici and Lactococcus garvieae suggest that their antimicrobial activity is related to heat-stable proteins/peptides that presumably belong to the class IIa bacteriocins. In conclusion, we present a pipeline of methods for high-throughput screening of strain libraries for potential starter cultures and probiotics producing antimicrobial compounds and their identification and analysis.

Optimization and production of antimicrobial compounds by Aspergillus flavus MTCC 13062 and its synergistic studies

The current study was focused on the antimicrobial activities of Aspergillus flavus MTCC 13062 strain isolated from solid waste dumping site, Hisar (INDIA) which showed remarkable inhibitory effect against the test organisms ( Streptococcus gordonii, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella enterica , Pseudomonas aeruginosa, Pseudomonas florescens and Candida albicans ). Response Surface Methodology (RSM) was performed to optimize the production of bioactive compounds by Aspergillus flavus MTCC 13062 which considerably increased the antimicrobial activity by 22%, 75% and 50% in E. coli , S. aureus and C. albicans, respectively at pH 7.5, temperature 28 °C and incubation period of 7 days. LC-MS was used to confirm the molecular weight and purity of the bioactive compound, while FTIR spectroscopy confirmed its structural characterization. Minimum inhibitory concentration (MIC) assay was carried out using dichloromethane extracts of Aspergillus flavus MTCC 13062 and results indicated MIC value as low as 25 μg/mL against S. aureus and E. coli while 50 μg/mL against C. albicans. Antifungal susceptibility test of Aspergillus flavus MTCC 13062 revealed that it was susceptible to Itraconazole, Fluconazole, Terbinafine, Kanamycin and Amphotericin B with zone of inhibition ranging from 10 to 24 mm . Furthermore, synergistic studies were carried out using commercial antibiotics in combination with the fungal extract and promising results were observed. We conclude that future implementation of the combinatorial results may help reduce the prescribed dosage of these antibiotics and thereby reducing the potential risks associated with the high doses of these harmful antibiotics. • A. flavus MTCC 13062 with antimicrobial potential was isolated from solid waste. • Optimization (RSM) yielded increase in antimicrobial activity by 1.1–1.7 fold. • Glycenopyrin (C 9 H 13 NO 5 ) identified as the bioactive compound using LC-MS analysis. • Purified extracts showed MIC values as 25 μg/mL against E. coli and S. aureus. • Synergism was observed on combining fungal extract with selected antibiotics.

In silico comparative genomics analysis of Lactiplantibacillus plantarum DW12, a potential gamma-aminobutyric acid (GABA)-producing strain

Gamma-aminobutyric acid (GABA) is an amino that plays a major role as a neurotransmitter. It iscommonly produced by lactic acid bacteria (LAB) naturally found in fermented food and fruit. Lactiplantibacillus plantarum DW12 is a high potential GABA-producing strain isolated from a fermented beverage. In this study, to highlight its ability to produce GABA, we sequenced the genome of L. plantarum DW12 and then performed comprehensive bioinformatics and meta-analysis to compare the genomic data of previously published genomes. Also, the evolutionary analysis among L. plantarum species was demonstrated using pan-genome analysis against 576 genomes from the database. As a result, the DW12 genome comprises one circular chromosome of 3,217,574 bp. It contains several genes that encode for the production of antimicrobial compounds including plantaricin A, E, F, J, K, and N. The glutamic acid decarboxylase (GAD) operon was found in the DW12 genome, suggests a high potential of producing GABA in this strain. Therefore, L. plantarum DW12 could be a good candidate as a starter culture in the beverage and food industries due to its safety aspects and ability to produce GABA.

First Insight into the Diversity and Antibacterial Potential of Psychrophilic and Psychotrophic Microbial Communities of Abandoned Amber Quarry

Natural habitats, including extreme ones, are potential sources of new antimicrobial compound producers, such as bacteriocins and enzymes, capable of degrading the matrix polysaccharides of bacterial biofilms. This study aimed to investigate biodiversity and evaluate the antibacterial potential of psychrophilic and psychrotrophic microbial communities of the flooded Walter amber quarry (Kaliningrad region, Russia). As a result of 16S rDNA high-throughput profiling, 127 genera of bacteria belonging to 12 phyla of bacteria were found in sediment samples: Acidobacteria sp., Actinobacteria sp., Armatimonadetes sp., Bacteroidetes sp., Chloroflexi sp., Cyanobacteria sp., Firmicutes sp., Gemmatimonadetes sp., Planctomycetes sp., Proteobacteria sp., Tenericutes sp., and Verrucomicrobia sp. The dominant bacteria groups were the families Ruminococcaceae and Lachnospiraceae, belonging to the order Clostridiales phylum Firmicutes. Analysis of enrichment cultures obtained from sediments showed the presence of antibacterial and cellulolytic activity. It seems likely that the bacteria of the studied communities are producers of antimicrobial compounds and have the potential for biotechnological use.

Draft Genome Sequence of Janthinobacterium lividum ID1246, Isolated from a Rainbow Trout Hatchery Biofilm.

ABSTRACTWe present a draft genome sequence of Janthinobacterium lividum strain ID1246, isolated from within a rainbow trout hatchery raceway. Janthinobacterium spp. are well-known producers of antimicrobial compounds. Due to the unique isolation source, this genome may yield novel biosynthetic gene clusters.

Genomic diversity of Serratia proteamaculans and Serratia liquefaciens predominant in seafood products and spoilage potential analyses

Serratia sp. cause food losses and waste due to spoilage; it is noteworthy that they represent a dominant population in seafood. The main spoilage associated species comprise S. liquefaciens, S. grimesii, S. proteamaculans and S. quinivorans, also known as S. liquefaciens-like strains. These species are difficult to discriminate since classical 16S rRNA gene-based sequences do not possess sufficient resolution. In this study, a phylogeny based on the short-length luxS gene was able to speciate 47 Serratia isolates from seafood, with S. proteamaculans being the main species from fresh salmon and tuna, cold-smoked salmon, and cooked shrimp while S. liquefaciens was only found in cold-smoked salmon.The genome of the first S. proteamaculans strain isolated from the seafood matrix (CD3406 strain) was sequenced. Pangenome analyses of S. proteamaculans and S. liquefaciens indicated high adaptation potential. Biosynthetic pathways involved in antimicrobial compounds production and in the main seafood spoilage compounds were also identified. The genetic equipment highlighted in this study contributed to gain further insights into the predominance of Serratia in seafood products and their capacity to spoil.

At the Gate of Mutualism: Identification of Genomic Traits Predisposing to Insect-Bacterial Symbiosis in Pathogenic Strains of the Aphid Symbiont Serratia symbiotica.

Mutualistic associations between insects and heritable bacterial symbionts are ubiquitous in nature. The aphid symbiont Serratia symbiotica is a valuable candidate for studying the evolution of bacterial symbiosis in insects because it includes a wide diversity of strains that reflect the diverse relationships in which bacteria can be engaged with insects, from pathogenic interactions to obligate intracellular mutualism. The recent discovery of culturable strains, which are hypothesized to resemble the ancestors of intracellular strains, provide an opportunity to study the mechanisms underlying bacterial symbiosis in its early stages. In this study, we analyzed the genomes of three of these culturable strains that are pathogenic to aphid hosts, and performed comparative genomic analyses including mutualistic host-dependent strains. All three genomes are larger than those of the host-restricted S. symbiotica strains described so far, and show significant enrichment in pseudogenes and mobile elements, suggesting that these three pathogenic strains are in the early stages of the adaptation to their host. Compared to their intracellular mutualistic relatives, the three strains harbor a greater diversity of genes coding for virulence factors and metabolic pathways, suggesting that they are likely adapted to infect new hosts and are a potential source of metabolic innovation for insects. The presence in their genomes of secondary metabolism gene clusters associated with the production of antimicrobial compounds and phytotoxins supports the hypothesis that S. symbiotia symbionts evolved from plant-associated strains and that plants may serve as intermediate hosts. Mutualistic associations between insects and bacteria are the result of independent transitions to endosymbiosis initiated by the acquisition of environmental progenitors. In this context, the genomes of free-living S. symbiotica strains provide a rare opportunity to study the inventory of genes held by bacterial associates of insects that are at the gateway to a host-dependent lifestyle.

The growth and production of antimicrobial compounds from Lactobacillus plantarum IIA-1A5 on cheese whey medium

Plantaricin IIA-1A5 is a bacteriocin produced by Lactobacillus plantarum IIA-1A5 which is isolated from Indonesian beef, and it inhibits activity of Gram negative and positive pathogenic bacteria. However, preparation of the antibacterial agent for further applications or studies is costly due to the usage of a bacterial medium. Therefore, this study was aimed to investigate the feasibility of cheese whey as a growth medium for production of the bacteriocin. The growth curve of Lactobacillus plantarum IIA-1A5 in producing antimicrobial compounds was found to occur in the logarithmic phase with an incubation time of 28 and 32 hours. Purification of plantaricin IIA-1A5 produced peptides with a molecular weight of 9.59 kDa consisting of whey and whey+ (20g/L sucrose, 12.5 g/L tryptone and 7.5 g/L yeast extract); thus, the peptide was grouped as class IIa (&lt;10 kDa) bacteriocin. The protein concentration of plantaricin IIA-1A5 with whey+ (sucrose, tryptone, and yeast extract) treatment and whey treatment was 1883.17 mg/ml and lower than 325.58 mg/ml, respectively. Based on the antimicrobial activity test using a paper disc method, plantaricin IIA-1A5 demonstrated antimicrobial activity against Staphylococcus aureus ATCC 25923; the whey and whey+ treatment yielded 38.02 IU/dL and 321 IU/dL, respectively, while antimicrobial activity against Escherichia coli ATCC 25922 using whey and whey+ treatment yielded 44.85 IU/dL and 172.08 IU/dL, respectively. The effectiveness of the antimicrobial properties of plantaricin IIA-1A5 in the whey medium is proven through the results of this study. In short, the whey is appropriate growth medium for bacteriocin production.