Use Of Strains Research Articles

Approach to Strain Selection and the Propagation of Viral Stocks for Venezuelan Equine Encephalitis Virus Vaccine Efficacy Testing under the Animal Rule.

Licensure of a vaccine to protect against aerosolized Venezuelan equine encephalitis virus (VEEV) requires use of the U.S. Food and Drug Administration (FDA) Animal Rule to assess vaccine efficacy as human studies are not feasible or ethical. An approach to selecting VEEV challenge strains for use under the Animal Rule was developed, taking into account Department of Defense (DOD) vaccine requirements, FDA Animal Rule guidelines, strain availability, and lessons learned from the generation of filovirus challenge agents within the Filovirus Animal Nonclinical Group (FANG). Initial down-selection to VEEV IAB and IC epizootic varieties was based on the DOD objective for vaccine protection in a bioterrorism event. The subsequent down-selection of VEEV IAB and IC isolates was based on isolate availability, origin, virulence, culture and animal passage history, known disease progression in animal models, relevancy to human disease, and ability to generate sufficient challenge material. Methods for the propagation of viral stocks (use of uncloned (wild-type), plaque-cloned, versus cDNA-cloned virus) to minimize variability in the potency of the resulting challenge materials were also reviewed. The presented processes for VEEV strain selection and the propagation of viral stocks may serve as a template for animal model development product testing under the Animal Rule to other viral vaccine programs. This manuscript is based on the culmination of work presented at the “Alphavirus Workshop” organized and hosted by the Joint Vaccine Acquisition Program (JVAP) on 15 December 2014 at Fort Detrick, Maryland, USA.

Microbiota of Sardinian Goat's Milk and Preliminary Characterization of Prevalent LAB Species for Starter or Adjunct Cultures Development.

This work was performed to study the microbiota of raw goat's milk (67 samples) collected in different areas of Sardinia, in order to select autochthonous lactic acid bacteria (LAB) strains for use in goat cheese manufacturing. Total mesophilic bacteria ranged between 105 and 107 cfu/mL; mean counts of Enterobacteriaceae did not exceed 4 log cfu/mL whereas those of E. coli and coagulase-positive staphylococci were lower than 1.5 and 2 log ufc /ml, respectively. Neither Salmonella spp. nor Listeria monocytogenes were recovered. The numbers of total LAB were in the range from 104 to 107 cfu/mL and mean yeasts counts varied between 103 and 105 cfu/mL. The most frequently isolated LAB species were Lactococcus lactis subsp. lactis and Lactobacillus paracasei. The presence of Enterococcus faecium was also noteworthy. The in vitro study of some functional characteristics related to technological properties of the strains belonging to these species allowed to point out some strains possessing good potential for use as adjunct or starter cultures in the production of cheese.

Bioprospecting of polyhydroxyalkanoates-producing bacteria from Indonesian marine environment

Abstract. Tan WA, Wijaya I, Purwadaria T. 2019. Bioprospecting of polyhydroxyalkanoates-producing bacteria from Indonesian marine environment. Biodiversitas 20: 1309-1315. Polyhydroxyalkanoates (PHA) are potential alternates to conventional synthetic plastics. PHA production in bacteria involves PHA synthase gene encoded by phaC. In this study, we isolated PHA-producing bacteria from the coastline and 1 mile from the coastline of three beaches in Indonesia. Further phaC detection and characterization of PHA production were conducted. The isolates were subjected to phylogenetic analysis based on 16S rDNA. Red Nile staining on minimal agar revealed that twenty-three isolates showed orange fluorescent, which indicated that they accumulated PHA in their cells. PCR detection showed the presence of PHA synthase class I-encoding gene phaC in twelve isolates. One representative amplicon was sequenced to verify its identity, in which it shared 86% similarity with the PHA synthase class I-encoding gene from an uncultured bacterium. Interestingly, the production of PHA in isolate ST.PA.75, which was closely related to Vibrio sp., was 2.1-fold higher than that in the Ralstonia eutropha JMP134 control. Three isolates showed similarity with bacterial genera and/or species for which PHA producing phenotypes had never been described before TP.SWC.20, which was closely related to Microbacterium arborescens, as well as TP.SWC.33 and TP.SWC.85, which were similar to Psychrobacter spp. Phylogenetic analysis showed that the PHA producing isolates were clustered into three phyla: γ-Proteobacteria, Actinomycetes, and Bacilli. A majority of the isolates (75%) were related to γ-Proteobacteria. In this study, we uncovered diverse novel promising strains for use in the production of PHA as a more environmentally-friendly alternative to hydrocarbon-based plastics.

Effect of Consumption Buffaloe's Milk Fortified with Probiotic Yeasts on Rat Serum Lipids v

The using of four yeast strains (two cultures belonging to each S. cerevisiae and G. candidum) to withstand environmental conditions similar to the human digestion tract (probiotic criteria) were examined. The survival of these strains at low pH, in the presence of bile salt, in intestinal juice, also their ability to assimilate cholesterol were followed. However, the obtained results indicate that S. cerevisiae AAA3 and G. candidum GG1, may be promising candidate strains for use as probiotics. Thus, the potential role of these probiotic yeast cultures on serum lipid of rats was adopted. Twenty-four male albino rats were randomly and equally divided into four groups, six rats each. These rats were acclimatized on basal diet for 7 days before starting the experiment. The first group was fed on basal diet (cont. I), the second group was offered basal diet plus pasteurized buffalo's milk (6.5% fat). The rest two groups were fed on basal diet plus buffalo's milk in addition to either S. cerevisiae or G. candidum. Blood samples were collected at the beginning of the experiment (after adaptation period) and at the end of experiment. According to the result of serum analysis, total cholesterol and LDL- cholesterol levels in rats fed on S. cerevisiae (group 3) were decreased by 23% and 31.59% respectively. While, the corresponding values for rats consumed G. candidum were relatively lower, actually 21.46% and 29.12% respectively. Moreover, serum triglycerides concentrations reduced by 4.79% and 5.30% for rats in group 3 and 4, respectively as compared with control 1. Furthermore, data obtained declared that rats fed on either S. cerevisiae or G. candidum reduced markedly the atherogenic indexes 1 and 2 by mean values of 11.52, 23.86% and 10.1, 21.49% respectively, as compared with control 1. Continuously, rats fed on both yeast strains showed significant antagonistic effect against either coliform or staphylococci, where the reduction in their populations, actually 10.57, 7.42% for group 3 and 8.30, 18.22% for group 4, respectively.

The present & the past: a review of newly accessioned bacterial strains into the UK’s National Collection of Type Cultures

The National Collection of Type Cultures (NCTC) is a bacterial culture collection which is taxonomically and biologically diverse. NCTC holds approximately 6000 different strains from over 900 different species; among them strains originally isolated in the 19th century, strains for use as controls as stipulated EUCAST and ISO guidelines, type strains on which the description of bacterial species are based and other strains from a variety of backgrounds. The remit of NCTC is to provide authentic bacterial cultures of medical and veterinary interest to the scientific community, to support and enhance the reproducibility of scientific research and to improve global public health. To fulfil this remit, remain scientifically relevant and to preserve the legacy of contemporary medical bacteriology for future scientists, NCTC accessions strains of clinical significance: such as recently circulating and outbreak strains, diagnostic escape mutants and strains with novel antimicrobial resistance profiles. In 2018, 166 bacterial strains were accessioned into the NCTC and made available to the scientific community. These include NCTC 14052: a reference strain for emergent hyper-virulent K. pneumoniae, 4 type strains of newly described bacterial species, 82 strains accessioned from the Murray Collection of pre-antibiotic era Enterobacteriaceae and 8 strains with antimicrobial resistance mechanisms previously unrepresented in the collection, including NCTC 14208: a N. gonorrhoeae isolated from an instance of combined ceftriaxone and azithromycin treatment failure. Through literature review we have highlighted their value to the scientific community, both in their own right and in the context of bacterial strains already held by the NCTC.

Phosphate-Solubilizing Pseudomonas sp. Strain P34-L Promotes Wheat Growth by Colonizing the Wheat Rhizosphere and Improving the Wheat Root System and Soil Phosphorus Nutritional Status

Rhizosphere colonization is a requirement for field applications of plant growth-promoting rhizobacteria (PGPR). Complex signal exchanges and mutual recognition occur between microbes and plants. Here, the phosphate-solubilizing strain Pseudomonas sp. P34, which is a type of PGPR with affinity to wheat, was isolated from a wheat rhizosphere via wheat germ agglutinin. A pTR102 plasmid harboring the luciferase luxAB gene was transferred into P34. The labeled strain (P34-L) was then used to track the temporal and spatial characteristics of rhizosphere colonization and examine the effects of colonization on wheat development. The transcript levels of the phosphate transporter gene TaPT4, a phosphorus deficiency indicator, in wheat roots were monitored by quantitative reverse transcription PCR (qRT-PCR). The results indicated that P34-L could survive within the wheat rhizosphere for a long time and colonize new spaces in the wheat rhizosphere following the elongation of wheat roots. Compared with uninoculated wheat plants, plants inoculated with P34-L exhibited significantly increased phosphorus accumulation in the leaves; seedling and root weight; total root length; root projection area; root surface area; and number of root tips, forks, and crossings, thus demonstrating the great value of applying this strain in wheat production by promoting root growth and dry matter accumulation. The downregulation of TaPT4 transcript levels in the wheat roots also suggested that a high-phosphorus environment was established by P34-L. These results lay a foundation for further research on the relationships between PGPR and their host plants. Moreover, a potentially ideal biofertilizer-producing strain for use in sustainable agriculture was developed.

Xylose fermentation efficiency of industrial Saccharomyces cerevisiae yeast with separate or combined xylose reductase/xylitol dehydrogenase and xylose isomerase pathways

BackgroundXylose isomerase (XI) and xylose reductase/xylitol dehydrogenase (XR/XDH) pathways have been extensively used to confer xylose assimilation capacity to Saccharomyces cerevisiae and tackle one of the major bottlenecks in the attainment of economically viable lignocellulosic ethanol production. Nevertheless, there is a lack of studies comparing the efficiency of those pathways both separately and combined. In this work, the XI and/or XR/XDH pathways were introduced into two robust industrial S. cerevisiae strains, evaluated in synthetic media and corn cob hemicellulosic hydrolysate and the results were correlated with the differential enzyme activities found in the xylose-pathway engineered strains.ResultsThe sole expression of XI was found to increase the fermentative capacity of both strains in synthetic media at 30 °C and 40 °C: decreasing xylitol accumulation and improving xylose consumption and ethanol production. Similar results were observed in fermentations of detoxified hydrolysate. However, in the presence of lignocellulosic-derived inhibitors, a positive synergistic effect resulted from the expression of both XI and XR/XDH, possibly caused by a cofactor equilibrium between the XDH and furan detoxifying enzymes, increasing the ethanol yield by more than 38%.ConclusionsThis study clearly shows an advantage of using the XI from Clostridium phytofermentans to attain high ethanol productivities and yields from xylose. Furthermore, and for the first time, the simultaneous utilization of XR/XDH and XI pathways was compared to the single expression of XR/XDH or XI and was found to improve ethanol production from non-detoxified hemicellulosic hydrolysates. These results extend the knowledge regarding S. cerevisiae xylose assimilation metabolism and pave the way for the construction of more efficient strains for use in lignocellulosic industrial processes.

Growth promotion of Guinea grass by diazotrophic bacteria1

ABSTRACT The Panicum maximum species (cv. Mombaça) is a forage plant well adapted to the different edaphoclimatic conditions found in Brazil; however, it requires high nitrogen fertilizer doses to ensure high yields. The present study aimed to assess the inoculation effect with associative diazotrophic bacteria strains on the yield and bromatological characteristics of the Guinea grass. A randomized block design was used, consisting of 25 treatments, being 23 of them inoculated with diazotrophic bacteria and two without inoculation (one with and the other without mineral nitrogen), with four repetitions. The analyzed variables were stem diameter; leaf width and length; leaf, stem and root dry mass yield; crude protein; acid and neutral detergent fibers. There were no differences among the treatments for root dry mass, stem diameter and acid detergent fiber. For the remaining variables, a positive effect of the inoculation with diazotrophic bacteria was observed, particularly for the following Unifenas strains: 100-06, 100-13, 100-26, 100-30, 10-35, 100-54, 100-69, 100-71 and 100-94. This reveals the potential of these bacterial strains for use at the sustainable production of the Guinea grass with a reduction in the use of nitrogen inputs.

Impact of probiotic Lactobacillus sp. on autochthonous lactobacilli in weaned piglets.

This study aimed to determine whether host-adapted lactobacilli exhibit superior survival during intestinal transit relative to nomadic and free-living organisms, and to characterize the impact of probiotic lactobacilli on autochthonous lactobacilli. Mixed cultures of Lactobacillus casei K9-1 and Lactobacillus fermentum K9-2, or reutericyclin producing Lactobacillus reuteri and its isogenic mutant were fed to piglets as freeze-dried culture, or as part of fermented feed. Lactobacilli in digesta and faecal samples were quantified by strain-specific quantitative PCR (qPCR), high-resolution-melting curve qPCR, and high-throughput sequencing of 16S rRNA gene sequence tags. The abundance of the host adapted L. reuteri in digesta and faeces was higher (P<0·05) when compared to L. casei or L. fermentum. Feed fermentation or chemical acidification of feed reduced (P<0·05) cell counts of Lactobacillus salivarius in colonic digesta. The reutericyclin producing L. reuteri TMW1.656 transiently reduced (P<0·05) the faecal abundance of lactobacilli. However, the overall impact of probiotic intervention on autochthonous lactobacilli was minor. The vertebrate host-adapted L. reuteri survives better during intestinal transit of piglets compared to L. casei and L. fermentum. Ecology and lifestyle of Lactobacillus strains may be suitable criteria for selection of probiotic strains for use in swine production.

Activity of native and commercial strains of Metarhizium spp. against the poultry red mite Dermanyssus gallinae under different environmental conditions

The poultry red mite (PRM), Dermanyssus gallinae, is a major pest of laying hens with extremely limited control means. To evaluate the potential of natural and commercial entomopathogenic fungi (EPF) for use against D. gallinae, we tested four wild populations of D. gallinae from Israeli farms. The genus Aspergillus was identified as the most abundant isolates from the mites. Additionally, eight new isolates of Metarhizium belonging to the specie M. brunneum were identified. At all sites from which mites were collected in both seasons, the abundance of fungi on D. gallinae was greater during the winter season than during the summer season. Through indirect inoculations of adult D. gallinae, we examined the virulence of the native Metarhizium species, the commercial strain Ma-43 and a previously described acaropathogenic strain (Ma-7). All of the Metarhizium strains caused 56–95% mortality of adult mites by seven days after inoculation at a concentration of 5 × 105 conidia per cm2. The efficacies of Ma-43, Ma-7 and the most promising native strain were tested under optimal abiotic conditions (28°C; 85–100% RH) and abiotic conditions similar to those typically found in a poultry house (30 °C; 60% RH). Under optimal conditions, the efficacy of all three stains ranged between 85 and 92%. In contrast, under poultry-house conditions, the efficacy of control ranged between 30 and 40%. The incidence of mycoses on mite cadavers was significantly decreased under poultry-house conditions. These results demonstrate the potential of native and commercial Metarhizium strains for use as biopesticides. Future research should address suitable delivery methods and formulations for the effective control of D. gallinae under poultry-house conditions.

Lactobacilli with superoxide dismutase-like or catalase activity are more effective in alleviating inflammation in an inflammatory bowel disease mouse model

PurposeSome lactobacilli, which possess superoxide dismutase-like activity and catalase activity naturally, have strong antioxidative properties. The aim of this study was to identify such strains and check which of them play a crucial role in alleviating intestinal inflammation.MethodsWe selected two Lactobacillus strains for use in animal studies: L. plantarum 30B (which has the highest catalase activity) and L. acidophilus 900 (which has the highest dismutase-like activity). Forty mice (C57B1/6J) were divided into four experimental groups with ten mice in each group. Group I (control group) was not supplemented with Lactobacillus, group II (catalase group) was orally supplemented with L. plantarum 30B, group III (dismutase-like group) was supplemented with L. acidophilus 900, and group IV (mixed group) was supplemented with both Lactobacillus strains. For 23 days, the temperature and body mass of each mouse were recorded and fecal samples for microbiological examination were collected. On day 23, the animals were sacrificed, and their intestines were removed for microbiological and histopathological studies.ResultsCompared to the control group, the highest drop in the body temperature was observed in groups II (P<0.05) and IV (P<0.05). Similarly, groups II (P<0.05) and IV (P<0.05) had the highest drop in body mass. Moreover, histopathological evaluation of colon fragments showed intracryptic abscesses in these groups. Group III mice showed most limited degree of inflammation.ConclusionLactobacillus strains with dismutase-like activity are more effective in alleviating intestinal inflammation than strains producing catalase, suggesting that superoxide anion radical decomposition is crucial in this process.

Physiological background of the remarkably high Cd2+ tolerance of the Aspergillus fumigatus Af293 strain.

The physiological background of the unusually high cadmium tolerance (MIC50 > 2 mM) of Aspergillus fumigatus Af293 was investigated. The cadmium tolerance of the tested environmental and clinical A. fumigatus strains varied over a wide range (0.25 mM < MIC50 < 1 mM). Only the Af293 strain showed a MIC50 value of >2 mM, and this phenotype was accompanied by increased in vivo virulence in mice. A strong correlation was found between the cadmium tolerance and the transcription of the pcaA gene, which encodes a putative cadmium efflux pump. The cadmium tolerance also correlated with the iron tolerance and the extracellular siderophore production of the strains. In addition to these findings, Af293 did not show the synergism between iron toxicity and cadmium toxicity that was detected in the other strains. Based on these results, we suggest that the primary function of PcaA should be acting as a ferrous iron pump and protecting cells from iron overload. Nevertheless, the heterologous expression of pcaA may represent an attractive strain improvement strategy to construct fungal strains for use in biosorption or biomining processes or to prevent accumulation of this toxic metal in crops.

The Development of a New Computer-Adaptive Test to Evaluate Strain in Caregivers of Individuals With TBI: TBI-CareQOL Caregiver Strain

ObjectiveTo develop a new measure of caregiver strain for use in caregivers of individuals with traumatic brain injury (TBI), Traumatic Brain Injury Caregiver Quality of Life (TBI-CareQOL) Caregiver Strain. DesignQualitative data, literature reviews, and cross-sectional survey study. SettingThree TBI Model Systems rehabilitation hospitals, an academic medical center, and a military medical treatment facility. ParticipantsCaregivers (N=560) of civilians (n=344) or service members/veterans (SMVs) with TBI (n=216). InterventionsNot applicable. Main Outcome MeasureTBI-CareQOL Caregiver Strain Item Bank. ResultsExploratory and confirmatory factor analyses, a graded response model (GRM) and differential item functioning supported the retention of 33 items in the final measure. GRM calibration data was used to inform the selection of a 6-item static short form, and to program the TBI-CareQOL Caregiver Strain computer-adaptive test (CAT). CAT simulation analyses indicated a 0.97 correlation between the CAT scores and the full item-bank. Three-week test-retest reliability was strong (r=0.83). ConclusionsThe new TBI-CareQOL Caregiver Strain CAT and corresponding 6-item short form were developed using established rigorous measurement development standards; this is the first self-reported measure developed to evaluate caregiver strain in caregivers of individuals with TBI.

Combinatorial Fine-Tuning of Phospholipase D Expression by Bacillus subtilis WB600 for the Production of Phosphatidylserine.

Phospholipase D has great commercial value due to its transphosphatidylation products that can be used in the food and medicine industries. In order to construct a strain for use in the production of PLD, we employed a series of combinatorial strategies to increase PLD expression in Bacillus subtilis WB600. These strategies included screening of signal peptides, selection of different plasmids, and optimization of the sequences of the ribosome-binding site (RBS) and the spacer region. We found that using the signal peptide amyE results in the highest extracellular PLD activity (11.3 U/ml) and in a PLD expression level 5.27-fold higher than when the endogenous signal peptide is used. Furthermore, the strain harboring the recombinant expression plasmid pMA0911-PLD-amyE-his produced PLD with activity enhanced by 69.03% (19.1 U/ml). We then used the online tool \RBS Calculator v2.0 to optimize the sequences of the RBS and the spacer. Using the optimized sequences resulted in an increase in the enzyme activity by about 26.7% (24.2 U/ml). In addition, we found through a transfer experiment that the retention rate of the recombinant plasmid after 5 generations was still 100%. The final product, phosphatidylserine (PS), was successfully detected, with transphosphatidylation selectivity at 74.6%. This is similar to the values for the original producer.

Effect of Burkholderia tropica and Herbaspirillum frisingense strains on sorghum growth is plant genotype dependent.

Sorghum is a multipurpose crop that is cultivated worldwide. Plant growth-promoting bacteria (PGPB) have important roles in enhancing sorghum biomass and nutrient uptake and suppressing plant pathogens. The aim of this research was to test the effects of the endophytic bacterial species Kosakonia radicincitans strain IAC/BECa 99, Enterobacter asburiae strain IAC/BECa 128, Pseudomonas fluorescens strain IAC/BECa 141, Burkholderia tropica strain IAC/BECa 135 and Herbaspirillum frisingense strain IAC/BECa 152 on the growth and root architecture of four sorghum cultivars (SRN-39, Shanqui-Red, BRS330, BRS509), with different uses and strigolactone profiles. We hypothesized that the different bacterial species would trigger different growth plant responses in different sorghum cultivars. Burkholderia tropica and H. frisingense significantly increased the plant biomass of cultivars SRN-39 and BRS330. Moreover, cultivar BRS330 inoculated with either strain displayed isolates significant decrease in average root diameter. This study shows that Burkholderia tropica strain IAC/BECa 135 and H. frisingense strain IAC/BECa 152 are promising PGPB strains for use as inocula for sustainable sorghum cultivation.

New Bacillus subtilis Strains as Promising Probiotics

The properties of new B. subtilis strains GM2 and GM5, isolated from potato rhizosphere and possessing high antimicrobial activity, were studied. The potential of the strains for their use as probiotics was characterized. The strains were resistant to bile and to a wide range of the ambient pH. B. subtilis strains GM2 and GM5 possessed proteolytic and phytate-hydrolyzing activity and proved to be safe for model animals. The strains were characterized by antagonistic properties against phytopathogenic micromycetes, as well as against pathogenic and opportunistic enterobacteria. B. subtilis GM2 and GM5 were concluded to be promising strains for use as probiotics.

Modelling invasive group A streptococcal disease using bioluminescence

BackgroundThe development of vaccines and evaluation of novel treatment strategies for invasive group A streptococcal (iGAS) disease requires suitable models of human infection that can be monitored longitudinally and are preferably non-invasive. Bio-photonic imaging provides an opportunity to reduce use of animals in infection modelling and refine the information that can be obtained, however the range of bioluminescent GAS strains available is limited. In this study we set out to develop bioluminescent iGAS strains for use in in vivo pneumonia and soft tissue disease models.ResultsUsing clinical emm1, emm3, and emm89 GAS strains that were transformed with constructs carrying the luxABCDE operon, growth and bioluminescence of transformed strains were characterised in vitro and in vivo.Emm3 and emm89 strains expressed detectable bioluminescence when transformed with a replicating plasmid and light production correlated with viable bacterial counts in vitro, however plasmid instability precluded use in the absence of antimicrobial pressure. Emm89 GAS transformed with an integrating construct demonstrated stable bioluminescence that was maintained in the absence of antibiotics. Bioluminescence of the emm89 strain correlated with viable bacterial counts both in vitro and immediately following infection in vivo. Although bioluminescence conferred a detectable fitness burden to the emm89 strain during soft tissue infection in vivo, it did not prevent dissemination to distant tissues.ConclusionDevelopment of stably bioluminescent GAS for use in vitro and in vivo models of infection should facilitate development of novel therapeutics and vaccines while also increasing our understanding of infection progression and transmission routes.

Biogenic amine and antibiotic resistance profiles determined for lactic acid bacteria and a propionibacterium prior to use as antifungal bioprotective cultures

Lactic acid bacteria (LAB) and propionibacteria are two microbial groups studied as alternatives to chemical preservatives in foods. As potential bioprotective cultures in the food industry, not only does antimicrobial efficiency need to be ensured, but safety criteria should be evaluated. Here, 21 LAB and 1 propionibacterium with previously determined antifungal properties were screened for two relevant criteria: biogenic amine production and antibiotic resistance patterns. Low risk profiles were observed for 15 strains, highlighting their potential industrial use as bioprotective cultures. Some exceptions were identified: both Lactobacillus buchneri strains tested were histamine-producers, while 1 Lactobacillus brevis, 2 Lactobacillus rhamnosus and 1 Leuconostoc mesenteroides strains were tyramine-producers. These same strains were resistant to up to 5 antibiotics, thus excluding them as candidates for industrial use. These results confirm the importance of ensuring safety criteria are met before considering a candidate strain for use as a bioprotective agent in food products.

Algal biophotovoltaic (BPV) device for generation of bioelectricity using Synechococcus elongatus (Cyanophyta)

The exploitation of renewable energy sources for delivering carbon neutral or carbon negative solutions has become challenging in the current era because conventional fuel sources are of finite origins. Algae are being used in the development of biophotovoltaic (BPV) platforms which are used to harvest solar energy for bioelectricity generation. Fast-growing algae have a high potential for converting CO2 from the atmosphere into biomass and valuable products. In photosynthesis light-driven splitting of water occurs, releasing a pair of electrons and generating O2. The electrons can be harvested and converted to bioelectricity. In this study, algal biofilms of a tropical cyanobacterial strain Synechococcus elongatus (UMACC 105) were formed on two types of electrodes, indium tin oxide (ITO) and reduced graphene oxide (rGO), and investigated for use in the algal biophotovoltaic (BPV) device. The highest maximum power density was registered in the rGO-based BPV device (0.538 ± 0.014 mW m−2). This illustrates the potential of this local algal strain for use in BPV devices to generate bioelectricity in both the light and dark conditions.

Isolation and characterization of efficient Phosphate Solubilizing &lt;i&gt;Bacillus&lt;/i&gt; (PSB) from different agro-ecological zones of Tigray soil, Ethiopia

Applications of biofertilizer have great practical importance for increasing fertility of the soil and reducing environmental pollution. Screening and characterizing phosphate solubilizing Bacillus (PSB) strains from different agroecologies of Tigray soil and in vitro assessment for the adaptability under different abiotic stress would help in selecting the most efficient strain for use as biofertilizer. A total of 64 soil samples were collected from different agro-ecological zones of Tigray and checked for the presence, capability and efficiency of PSB. Out of 64 soil samples 21 of them were phosphate solubilizing. These phosphate solubilizing strains again incubate at 37˚C for 48h on pikovskaya medium to see efficacy of phosphate solubilization. Highest efficiency was recorded in MUB28, MUB47and MUB64 isolates and also tolerant to acidity and alkaline up to pH4 and pH8, respectively. And difference was recorded in saline tolerance among the strains: MUB47 is the most saline tolerance strain which tolerate saline up to 513mM of sodium chloride (NaCl) but MUB28 and MUB64 have tolerated saline up to 340mM of NaCl. The identification of efficient PSB candidate strains with salt & pH tolerant features in the soil sample could have an implication on the end-users to obtain the desired beneficial effect such as maintaining soil healthy, provision of adequate phosphorus from soil to the plant and improving crop yield of Tigray Agriculture. Based on the morphological, microscopic, biochemical and physiological characterization, it may be inferred that the diversity among these efficient PSB strains is low. Keywords : Biofertilizer, Phosphate solubilizing Bacillus, Efficiency, Diversity, Agroecology, Adaptability, Ethiopia.