Uninoculated Control Research Articles

Effect of inoculation with Acaulospora and Glomus on the growth and nutrition of blueberries (Vaccinium corymbosum) with different fertilization levels

In recent years, the global demand for blueberries has been growing because of its nutraceutical properties in the fruits, which provide important benefits to human health. Colombia, thanks to its diversity, has a great opportunity to meet the blueberry demands of the global markets. In the present study, the effect of two arbuscular mycorrhizal fungi (AMF) of the genera Glomus and Acaulospora were evaluated on the growth of blueberry plants var. Biloxi, subjected to three levels of chemical fertilization (100, 50 and 0%), with the 100% level being optimal. The blueberry plants inoculated with Glomus under conditions of nutrient deficiency (50AMF1+) increased dry mass, height, number of basal branches, leaf area, root/shoot ratio, and chlorophyll concentration, which were significantly higher than in the plants without inoculation with nutrient deficiency (0AMF- and 50AMF-). The plants inoculated with Glomus achieved an increase in height, while the plants inoculated with Acaulospora increased the number of basal branches when grown under a nutrient deficiency (50AMF+1) in relation to the uninoculated controls (0AMF- and 50AMF-). The results suggested that the best association of blueberry occurs with Glomus, with increased plant growth and nutrition (N, P, K, Ca, Mg, and S).

The Potential of Pre-fermented Juice or Lactobacillus Inoculants to Improve the Fermentation Quality of Mixed Silage of Agro-Residue and Lucerne.

The objective of this study was to determine the effect of pre-fermented juice, Lactobacillus plantarum, and L. buchneri on chemical composition, fermentation, aerobic stability, dynamics of microbial community, and metabolic pathway of a mixture of lucerne, wheat bran (WB), and rice straw (RS). All mixtures were ensiled for 1, 3, 5, 7, 15, 30, and 45 days after treatment with uninoculated (control, C); L. plantarum [LP, 1 × 106 cfu/g of fresh weight (FW)]; L. buchneri (LB, 1 × 106 cfu/g of FW); LP + LB (LPB, 1 × 106 cfu/g of FW of each inoculant); and pre-fermented juice (J; 2 × 106 cfu/g of FW). Four lactic acid bacteria (LAB) species from three genera were cultured from the pre-fermented juice, with W. cibaria being dominant. The inoculants increased lactic acid (LA), decreased pH and ammonia nitrogen (AN) compared to C silage at earlier stages of ensiling, and high dry matter (DM) and water-soluble carbohydrate (WSC) content in inoculated silages. Adding LPB increased the abundance of L. plantarum, L. paralimentarius, and L. nodensis, resulting in the lowest pH. Pre-fermented juice enriched W. cibaria, L. sakei, L. parabrevis, Pseudomonas putida, and Stenotrophomonas maltophilia, mainly enhanced accumulation of acetic acid (AA) and LA, and decreased pH, crude protein losses, AN, and hemicellulose contents. L. buchneri and L. brevis had a high abundance in LB-treated and J silages, respectively, inhibited undesirable bacteria, and improved aerobic stability with more than 16 days. In addition, the metabolic pathways changed with time and L. buchneri inoculants promoted global metabolism. In conclusion, inoculations altered bacterial succession and metabolic pathways in silage; LB and pre-fermented juice enhanced ensiling by promoting pH reductions, enhancing concentrations of LA and AA, and extending aerobic stability more than 16 days.

Black Truffles Affect Quercus aliena Physiology and Root-Associated nirK- and nirS-Type Denitrifying Bacterial Communities in the Initial Stage of Inoculation.

Truffles (Tuber spp.) are edible ectomycorrhizal fungi with high economic value. Bacteria in ectomycorrhizosphere soils are considered to be associated with the nutrient uptake of truffles and hosts. Whether Tuber spp. inoculation can affect the growth of Quercus aliena, the ectomycorrhizosphere soil, and the rhizosphere nirK and nirS-denitrifier communities at the ectomycorrhizae formation stage is still unclear. Therefore, we inoculated Q. aliena with the black truffles Tuber melanosporum and Tuber indicum, determined the physiological activity and morphological indices of Q. aliena seedlings, analyzed the physicochemical properties of ectomycorrhizosphere soils, and applied DNA sequencing to assess the nirK and nirS- denitrifier community structure in ectomycorrhizosphere soils. Peroxidase activity was higher in the seedlings inoculated with T. melanosporum than in the T. indicum inoculation and uninoculated control treatments. The available phosphorus contents were lower and nitrate contents were higher in those with truffle inoculation, and T. melanosporum treatment differed more from the control than the T. indicum treatment. The richness of the nirK-community was highest in the T. indicum treatment and lowest in the uninoculated treatment. The differences in nirK-community composition across treatments were not statistically significant, but the nirS communities were different. The nirS-type bacteria correlated with three environmental factors (pH, available phosphorus, and nitrate contents), whereas the nirK-type bacteria were only associated with the nitrate contents. Generally, this work revealed that inoculation with Tuber spp. would change a few nutrient contents and richness of nirK-type bacteria and had little effects on growth of Q. aliena seedlings in the initial stage of inoculation. The results of this study may provide in-depth insights into the relationships between Tuber spp. and hosts, which should be taken into account when developing truffle production methods.

Synergistic Plant-Microbe Interactions between Endophytic Actinobacteria and Their Role in Plant Growth Promotion and Biological Control of Cotton under Salt Stress.

Bacterial endophytes are well-acknowledged inoculants to promote plant growth and enhance their resistance toward various pathogens and environmental stresses. In the present study, 71 endophytic strains associated with the medicinal plant Thymus roseus were screened for their plant growth promotion (PGP), and the applicability of potent strains as bioinoculant has been evaluated. Regarding PGP traits, the percentage of strains were positive for the siderophore production (84%), auxin synthesis (69%), diazotrophs (76%), phosphate solubilization (79%), and production of lytic enzymes (i.e., cellulase (64%), lipase (62%), protease (61%), chitinase (34%), and displayed antagonistic activity against Verticillium dahliae (74%) in vitro. The inoculation of strain XIEG05 and XIEG12 enhanced plant tolerance to salt stress significantly (p < 0.05) through the promotion of shoot, root development, and reduced the activities of antioxidant enzymes (SOD, POD, and CAT), compared with uninoculated controls in vivo. Furthermore, inoculation of strain XIEG57 was capable of reducing cotton disease incidence (DI) symptoms caused by V. dahliae at all tested salt concentrations. The GC-MS analysis showed that many compounds are known to have antimicrobial and antifungal activity. Our findings provide valuable information for applying strains XIEG05 and XIEG12 as bioinoculant fertilizers and biological control agent of cotton under saline soil conditions.

ResidualBradyrhizobiuminoculation effects on soybean performance and selected soil health parameters

AbstractThe persistence of inoculants from year to year in soybean [Glycine max (L.) Merr.] cultivation and the residual benefits in soybean production are pertinent to adopting such practices in sub‐Saharan Africa countries such as Ghana. A study was conducted to determine the residual effect of commercial rhizobium inoculants on soybean and selected soil health parameters after three cropping seasons. The experimental design was a split‐plot. The main plot consisted of three soybean cultivars (Jenguma, Afayak, and Songda), and the subplot comprised of three peat‐based commercial bradyrhizobium inoculants (Biofix, Legumefix, and NoduMax) and an uninoculated control. Assessments were made on nodulation, shoot dry matter (DM), grain yield, grain total N uptake, permanganate‐oxidizable carbon (POXC), soil pH, and potentially mineralizable C. Among the soybean cultivars, Afayak produced greater nodule mass on the lateral root and the whole root system compared with the other cultivars. Jenguma and Afayak yielded greater shoot DM relative to Songda. Regarding the inoculants, Biofix increased nodule mass on the lateral root and the whole root system compared with the control. Biofix and NoduMax produced superior grain yield relative to the control. Biofix also produced greater grain yield than Legumefix. A superior pod harvest index and an improved grain total N uptake were produced by Biofix compared with Legumefix and the control. Commercial inoculants enhanced POXC availability at harvest, whereas potentially mineralizable C declined with inoculation treatments. Commercial inoculants (Biofix and NoduMax) enhanced nodulation, grain yield, and selected soil health indicators 3 yr after inoculation.

Identification of Differentially Expressed Genes Reveal Conserved Mechanisms in the Rice-Magnaporthe oryzae Interaction

Magnaporthe oryzae causes rice blast disease and is responsible for major losses in rice production worldwide. Although numerous studies have focused on the interactions between Oryza sativa and M. oryzae, to date, the conserved mechanisms remain in part unclear. In this study, a comparative analysis of transcriptomes of O. sativa L. ssp. japonica cv. ‘Nipponbare’ interacting with three M. oryzae strains (248, 235, and 163) were performed to explore the conserved molecular mechanisms. Differentially expressed genes with similar expression patterns in the interactions between cultivar ‘Nipponbare’ and three M. oryzae strains were defined as Conserved Differentially Expressed Genes (CDEGs). These included 3,647 O. sativa CDEGs and 3,655 M. oryzae CDEGs. Four rice CDEGs (LOC_Os03g19270, LOC_Os07g36600, LOC_Os05g28740, and LOC_Os01g32780) encoding universal stress protein (USP) were induced within 24 h post-inoculation (hpi) by three M. oryzae strains. Meanwhile, overexpression of LOC_Os07g36600 resulted in enhanced rice resistance against M. oryzae. Furthermore, four rice genes coding light-harvesting chlorophyll a/b-binding (LHC) protein (LOC_Os02g52650, LOC_Os09g12540, LOC_Os11g13850, LOC_Os05g22730) were also identified as CDEGs and were induced at 48 hpi, which might contribute to blast resistance through reactive oxygen species (ROS) accumulation. MoCDIP4 is M. oryzae effector inducing rice cell death and were verified that include AA9 CAZy domain (namely GH61 domain). In this study, we found seven MoCDIP4-homologous genes coding proteins with signal peptides and AA9 CAZy domains, which were continuously up-regulated across all infection stages relative to uninoculated control. This study uncovered that genes are required for conserved mechanisms of rice-M. oryzae interaction, which includes rice genes encoding USP proteins and LHC proteins, as well as M. oryzae genes encoding AA9 proteins. This study will help us to understand how O. sativa responds to M. oryzae infections and the molecular mechanisms of M. oryzae pathogenicity.

Eimeria pragensis infection alters the gut microenvironment to favor extrinsic shiga toxin-producing Escherichia coli O157:H7 colonization in mice.

We examined the effects of Eimeria pragensis infection on intestinal peristalsis, goblet cell proliferation and intestinal flora in C57BL/6 mice. Intestinal peristalsis was evaluated by radiography using barium at 7days post-infection (p.i.). The intestinal peristalsis of E. pragensis-infected mice was significantly suppressed compared with uninfected control mice. Twenty-three mice were divided into 5 groups of 4 or 5 mice each; 2 groups of mice were infected with E. pragensis and the others were kept uninfected. At 7days p.i., E. pragensis-infected and -uninfected mice were sacrificed to examine goblet cell numbers in the intestines, and significant decreases were observed only in the infected mice. Shiga toxin-producing Escherichia coli (STEC) O157:H7 was inoculated orally in mice both infected and uninfected with E. pragensis at 7days p.i., with the remaining mice used as uninoculated controls. When mice were sacrificed at 2days after STEC inoculation, STEC was only detected in the intestines of E. pragensis-infected mice. Colonization of STEC was also confirmed by immunohistochemistry on the surface of epithelial cells in concurrently infected/inoculated mice. Also, an overgrowth of residential E. coli was observed only in E. pragensis-infected mice. These results suggest that E. pragensis induces the suppression of intestinal peristalsis and modifies the intestinal environment to facilitate artificially introduced STEC colonization and multiplication, in addition to residential E. coli overgrowth.

Control of Bacillus weihenstephanensis in Pasteurized Liquid Whole Eggs Formulated with Nisin

Bacillus weihenstephanensis can grow at refrigeration temperature and cause food poisoning. It has been isolated from liquid whole egg products. The moderate heat used for pasteurization of liquid egg products is ineffective for killing spore-forming bacteria, including Bacillus. Available predictive models and a pretrial study in broth suggested the potential for growth of Bacillus spp. under the tested conditions. Hence, hurdles such as storage of product below 4°C or use of preservatives would be needed to ensure the food safety of pasteurized egg products. This study evaluated the growth inhibition of B. weihenstephanensis in pasteurized liquid whole egg product formulated with 6.25 ppm of nisin during storage at refrigerated and refrigerated temperatures at abuse levels for a total 13 weeks in three replicate trials. At day 0, the product had a pH of 7.52 ± 0.29, while background microflora, such as aerobic plate counts (APC), presumptive Bacillus cereus and yeast and molds were <10 CFU/g. Product inoculated with target 2.5 log CFU/g of B. weihenstephanensis, stored at 4°C for 4 weeks and subsequently at 7 or 10°C for 9 weeks, exhibited no growth in all three replicate trials. Average counts reduced (P < 0.05) by at least 1 log in 6 weeks in all samples stored at either 7 or 10°C. Similarly, growth of total plate counts, presumptive Bacillus spp., and yeast and mold counts was not observed in uninoculated controls stored at 4°C for 4 weeks and subsequently at 7 or 10°C for 9 weeks. Visual and odor evaluation performed at each sampling time point showed no abnormalities. This study assessed the efficacy of the maximum level of nisin allowed for use in pasteurized liquid whole eggs and validated the inhibition of B. weihenstephanensis in the product for an extended shelf life of up to 13 weeks.

Genome Sequencing of Rahnella victoriana JZ-GX1 Provides New Insights Into Molecular and Genetic Mechanisms of Plant Growth Promotion

Genomic information for bacteria within the genus Rahnella remains limited. Rahnella sp. JZ-GX1 was previously isolated from the Pinus massoniana rhizosphere in China and shows potential as a plant growth-promoting (PGP) bacterium. In the present work, we combined the GridION Nanopore ONT and Illumina sequencing platforms to obtain the complete genome sequence of strain JZ-GX1, and the application effects of the strain in natural field environment was assessed. The whole genome of Rahnella sp. JZ-GX1 comprised a single circular chromosome (5,472,828 bp, G + C content of 53.53%) with 4,483 protein-coding sequences, 22 rRNAs, and 77 tRNAs. Based on whole genome phylogenetic and average nucleotide identity (ANI) analysis, the JZ-GX1 strain was reidentified as R. victoriana. Genes related to indole-3-acetic acid (IAA), phosphorus solubilization, nitrogen fixation, siderophores, acetoin, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, gamma-aminobutyric acid (GABA) production, spermidine and volatile organic compounds (VOCs) biosynthesis were present in the genome of strain JZ-GX1. In addition, these functions were also confirmed by in vitro experiments. Importantly, compared to uninoculated control plants, Pyrus serotina, Malus spectabilis, Populus euramericana (Dode) Guinier cv. “San Martino” (I-72 poplar) and Pinus elliottii plants inoculated with strain JZ-GX1 showed increased heights and ground diameters. These findings improve our understanding of R. victoriana JZ-GX1 as a potential biofertilizer in agriculture.

Host Genotype and Edaphic Factors Cumulatively Influence the Occurrence of Siderophore-producing Bacteria Associated with Rice (Oryza sativa L.)

Seed-borne rice endophytes are capable of disseminating into host plant tissues as well as to their rhizosphere. Here, we investigated the occurrence of siderophore-producing bacteria (SPB) in the seed endospheres of two distinct rice (Oryza sativa L.) cultivars, TK8 (ssp. japonica) and TCN1 (ssp. indica), and their dissemination into the rhizospheres through culture-dependent methods. Their patterns of occurrence in the rhizospheres as well as in the root and shoot tissues of 30 day-old cultivars grown in three different kinds of soils were tested. The significance of SPB on Fe sequestration of TCN1 was studied using Enterobacter sp. LS-756. TK8 seeds were found to be not only abundant in endopsheric SPB (&gt; 10-fold), but also exhibited enhanced SPB dissemination into the rhizosphere (1.3-fold) as compared to TCN1. The proportion of endophytic SPB was consistently higher in roots than in shoots, and it was found to decline with decreasing soil pH. A similar declining trend was further evident through the analysis of SPB composition in the rhizospheric and bulk soils. LS-756-inoculated TCN1 seedlings under low availability of Fe showed 32%, 178%, and 368% increases in Fe, chlorophyll, and chlorophyll b contents as compared to the uninoculated controls. Thus, the occurrence of seed-borne endophytic SPB and their dissemination into the rhizosphere vary significantly according to the rice genotype. Higher co-occurrence of SPB in the rhizosphere and internal root tissues of rice plants grown under Fe-limited conditions and the enhanced Fe uptake due to SPB inoculation substantiated their potential involvement in Fe sequestration.

Compatibility of fungicides with Trichoderma asperelloides and Azospirillum brasilense

The use of fungicides to control agricultural diseases has been increasing in agriculture. Thus, the biological control using fungus is an effective tool in the integrated diseases management. This study aimed to evaluate the compatibility of fungicides Certeza, Apron and Vitavax on the microorganisms Trichoderma asperelloides and Azospirillum brasilense. The experiments were conducted in vitro in a completely randomized design with a factorial arrangement 2 x 3 with three replications. The first factor composed of two doses and the second referred to the fungicides. The microorganisms were developed in PDA medium. After the medium has solidified, in a flow layer 10 µL of the fungal solution was added to each plate with the aid of an automatic pipette (D1, recommended dose; D2, double of recommended dose). Then, each Petri plate was centrally inoculated with a disc of Trichoderma asperelloides, in addition to the uninoculated control. For Azospirillum brasilense, the colony surface was scraped with the aid of a sterilized Drigalsky loop. Then, the filter of discs paper was dipped in the fungicides solution and placed on the medium surface. After this process, the plates were incubated in a BOD (Biochemical Oxygen Demand) at 26±2ºC and photoperiod 12 h. The parameters evaluated were a mycelial growth and sporulation. The results showed that there was no significant interaction between the factors. The fungicides Certeza (Tiofanato metílico + Fluazinam), Apron (Fludioxonil + Metalaxil-M) and Vitavax (Carboxina + Tiram) are considered compatible with Trichoderma asperelloides and Azospirillum brasilense. The fungicides can be used in an integrated disease management practices, priority must be given to use the products that have been shown to be less harmful.

First Report of Meloidogyne enterolobii Infecting Cassava (Manihot esculenta) Resulting in Root Galling Damage in Africa.

Meloidogyne enterolobii is a highly polyphagous tropical species of root knot nematode. It has been recorded to be causing major damage to a range of economically important crops and is increasingly recorded from new locations. The morphological similarity and overlap of characteristics with other commonly occurring species, especially M. incognita, has confused its diagnosis using morphometrics. Cassava (Manihot esculenta) is an important crop across the tropics, including Africa, where it is among the most important root and tuber crop for food security. Cassava can be heavily infected by root knot nematodes, which can incur heavy production losses. The main species known to affect cassava are M. incognita and M. javanica (Coyne and Affokpon, 2018). With the exception of one report of M. enterolobii morphologically identified from cassava roots during a survey in Brazil (Rosa et al., 2014), there is no record with molecular confirmation of it infecting the crop. In the absence of any molecular or isozyme confirmation, diagnosis of M. enterolobii is difficult to determine. In the current study, the species responsible for substantial galling damage (Fig. 1A) on several cassava roots growing in Ibadan, Nigeria (7°22'39″ N; 3°54'21″ E) were diagnosed. DNA isolated from juveniles recovered using a modified Baermann method (Hooper, 1986) from these roots was used for PCR amplification of the mitochondrial Nad5 using primer pair, NAD5F2 (5'-TATTTTTTGTTTGAGATATATTAG-3') and NAD5R1 (5'-CGTGAATCTTGATTTTCCATTTTT-3'). The 515 bp PCR DNA product was sequenced on both strands (GenBank Accession No. MW965454) and found to be 100% identical to M. enterolobii with those in the DNA sequence database (KU372358, KU372359) (Janssen et al., 2016; Kolombia et al., 2017). In addition, M. incognita was also recovered from the galled roots and identified using the same primers (GenBank Accession No. MW965455) indicating a combined species infection (Fig. 2). Cultures of M. enterolobii, developed from single egg masses were maintained on tomato plants and used to assess infection on cassava in 10 L pots filled with steam sterilized loam soil in the screenhouse. Cassava cv. IITA-TMS-IBA070593 cuttings planted in June, 2018 and repeated in April, 2019 were inoculated with 1,000 juveniles per pot at three weeks after planting, and then maintained for four months before quantifying the nematode densities in both roots and soil. Nematode reproduction factor (RF), calculated from total nematode densities (n=8) from soil and roots was as high as 44.3, compared to uninoculated controls. Molecular diagnostics of M. enterolobii, as above, confirms unequivocally the host status of cassava to this nematode. This study reports for the first time the infection of cassava by M. enterolobii under field conditions in Africa and for the first time demonstrates the host suitability of cassava to this nematode (Fig. 1B). M. enterolobii is among the most commonly occurring root-knot nematode species in West Africa (dos Santos et al., 2019). It is therefore anticipated that M. enterolobii has long been infecting, especially in West Africa, but has been overlooked due to its morphological similarity with M. incognita. Given the high reproductive ability of M. enterolobii on cassava and its highly aggressive nature on a range of crops, it is likely that it is causing, or will result in, high levels of losses on cassava in Africa.

Candidate marker genes and enzymes for selection of potato with resistance to early blight, caused by Alternaria alternata

Early blight, caused by Alternaria alternata (Fr.) Keissler is a serious disease of potato and other cultivated Solanum species. The molecular components defining defense responses to A. alternata in potato are limited. Host transcript accumulation after A. alternata inoculation of six potato genotypes (10/33/R1, 3/33/R2 and 21/33/R2, resistant to the pathogen, and 8707/106, 8703/804 and 8707/112, susceptible) was examined to develop understanding of mechanisms of their responses to A. alternata genotypes. The marker genes PR-2, ChtA, PR-5, PR1-b, PIN2, ERF3, PAL and LOX, activity of catalase (CAT), superoxide dismutase (SOD), peroxidase (POX), polyphenol oxidase (PPOs) and phenylalanine ammonia-lyase (PAL), as well as biomass growth parameters, were analysed. Expression of PR-2, ChtA, PR-5, PR1-b and PAL genes was greatly increased in the inoculated resistant genotypes compared to the susceptible genotypes and un-inoculated controls. Transcription levels of PIN2, ERF3 and LOX genes were decreased in resistant inoculated plants. Simultaneously, activities of POX, SOD and PPOs were greatly increased in the inoculated resistant host genotypes, compared to the susceptible and non-inoculated controls. CAT activity in genotype 21/33/R2 and PAL activity in resistant genotypes 21/33/R2 and 10/33/R1 increased in the susceptible and non-inoculated. Host growth parameters of inoculated plants decreased compared to un-inoculated controls. Knowledge of changes in gene expression levels and enzyme production in defense processes in infected potato plants can inform future studies to identify the defense mechanisms, and assist generation of potato cultivars resistant to early blight.

Aspergillus niger as a Biological Input for Improving Vegetable Seedling Production.

This study evaluated the potential of Aspergillus niger as an inoculant for growth promotion of vegetable seedlings. Seven vegetable species were evaluated in independent experiments carried out in 22 + 1 factorial schemes, with two doses of conidia (102 and 106 per plant) applied in two inoculation methods (seed treatment and in-furrow granular application), plus an uninoculated control. Experiments were carried out in a greenhouse. Growth parameters evaluated were shoot length, stem diameter, root volume, total root length, shoot and root fresh mass, shoot and root dry mass, and total dry mass. Regardless of the dose and inoculation method, seedlings inoculated with A. niger showed higher growth than uninoculated ones for all crops. The highest relative increase promoted by the fungus was observed for aboveground parts, increasing the production of shoot fresh mass of lettuce (61%), kale (40%), scarlet eggplant (101%), watermelon (38%), melon (16%), pepper (92%), and tomato (42%). Aspergillus niger inoculation also increased seedling root growth of lettuce, pepper, scarlet eggplant, watermelon, and tomato. This research shows that A. niger boosts the growth of all analyzed vegetables, appearing as a promising bio-input for vegetable seedling production.

Beneficial rhizospheric associated traits of chromate resistant bacteria for remediation of Cr (VI) contaminated soil

Agricultural fields are polluted with Cr (VI) due to the excessive use of industrial effluent for irrigation purposes. The current study was focused on evaluating and comparing the impact of chromate stress on wheat growth with distilled water and industrial effluent, with and without inoculation of bacteria. All chromate-resistant bacteria (UT8, UT25, AKR2, LM3, LM8, and NY2) isolated from polluted environments proficiently resisted K2CrO4 (1500 µg/ml). Staphylococcus simulans UT8 significantly produced plant-growth-promoting compounds such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase (365.05 nmol α-ketobutyrate mg/protein/h), indole acetic acid (IAA) production (77.14 µg/ml), and hydrogen cyanide (HCN). Strain UT8 showed an increment in the germination of seeds (38.47%), and root and shoot length (95.19 and 119.29%, respectively) under chromate stress (350 µg/ml) as compared to uninoculated controls. Similarly, UT8 inoculated seedlings also exhibited remarkable augmentation in the plant height (49.18%), tiller number/plant (87.96%), and grain yield/pot (108.96%) under chromate as compared to inoculum free treatment (control). Scanning electron micrographs of S. simulans UT8 treated seedlings root exhibited enhanced colonization in the presence of Cr (VI). Chromate removal potential of strain UT8 and the competence to secrete active phytohormones make it among the agronomically potent microorganisms to enhance wheat growth in metal-polluted soils.

Bradyrhizobium strains from Brazilian tropical soils promote increases in nodulation, growth and nitrogen fixation in mung bean

Mung bean [Vigna radiata (L.) Wilczek] is a legume of Asian origin cultivated in several countries, including Brazil, where its commercial cultivation has expanded in recent years. It has a promiscuous N2-fixing association with rhizobia, but nodulation in Brazilian soils has been highly variable. To achieve satisfactory yields with low production costs, studies are being carried out to select rhizobia from soils in Brazil that result in efficient symbiotic associations with mung bean. Previous studies indicate that only Bradyrhizobium strains were able to nodulate mung bean in Brazilian soils. The objective of this study was to evaluate the effect of 31 Bradyrhizobium strains and increasing levels of N fertilizer on nodulation, plant growth and N2 fixation. Bradyrhizobium strains resulted in increases of up to 71, 79, 43, 66, 40 and 55%, respectively, in nodule number and nodule, root and shoot biomasses, accumulated N and biological nitrogen fixation (BNF) contribution compared to the uninoculated control, however, there was no increase in grain yield. Compared to the control with N fertilizer, inoculated plants had lower biomass and accumulated N, despite the high BNF contribution. In general, strains of Bradyrhizobium japonicum superclade, especially those close to B. yuanmingense B071, showed greater efficiency compared to those of the superclade of B. elkanii. The application of N fertilizer increased root and shoot biomasses, however, significantly reduced nodulation. Bradyrhizobium strains isolated from Brazilian tropical soils showed potential for mung bean inoculation, however, the BNF contribution was not sufficient to meet the plant's N demand.

Biosurfactant producing multifarious Streptomyces puniceus RHPR9 of Coscinium fenestratum rhizosphere promotes plant growth in chilli.

The present study involves isolation of Streptomyces spp. from rhizosphere of Coscinium fenestratum Gaertn, an endangered medicinal plant from Western Ghats of Karnataka, India. Four potential isolates were identified by 16S rRNA sequencing as Streptomyces sp. RHPR3, Streptomyces puniceus RHPR9, Streptomyces sp. RHPR14 and Streptomyces mediolani RHPR25. An enrichment culture method was used for the isolation of Streptomyces spp. for biosurfactant activity. Among four potential Streptomyces spp., S. puniceus RHPR9 showed highest Emulsification index (EI) (78±0.2%) and Emulsification assay (EA) (223±0.2 EU mL-1). Thin layer chromatography, Fourier transform infrared spectroscopy (FTIR) and mass spectrometric analysis revealed that as glycolipid. Further confirmed by presence of fatty acids like hexanoic acid methyl ester, decanoic acid by Gas chromatography mass spectroscopy (GC-MS) analysis. S. puniceus RHPR9 showed a significant IAA production (41μg mL-1), solubilized P (749.1 μg mL-1), growth promotion of chilli (Capsicum annuum L.) was evaluated using paper towel method and greenhouse conditions. S. puniceus RHPR9 showed a significant increase in seed vigor index (2047) and increase in plant biomass (65%) when compared to uninoculated control. To our knowledge, this is the first report on epiphytic S. puniceus RHPR9 isolated from an endangered medicinal plant C. fenestratum Gaertn, for biosurfactant production and plant growth promotion activities.

Combined effect of mild pretreatment and fungal fermentation on nutritional characteristics of canola meal and nutrient digestibility of processed canola meal in rainbow trout

The effects of mild pretreatment and fungal fermentation on the nutritional characteristics of hexane extracted canola meal (HECM) was examined. HECM is a by-product of canola oil extraction process and has restricted use in animal diets due to presence of high levels of antinutritional factors (ANFs) and limited digestibility resulting in low nutrient availability. In this study, HECM was washed with water at different solid loading rates (SLR) to remove soluble ANFs. The wash process removed significant amounts of soluble carbohydrate and glucosinolates from HECM, yielding a meal with higher levels of proteins and amino acids when compared to raw HECM. The digestibility test conducted on rainbow trout with the feed that had 30% of fish meal replaced with washed HECM showed slight improvement with no statistical significance in protein digestibility when compared to HECM. Fermentation of washed HECM and raw HECM with mono- and co-cultures of Aureobasidium pullulans, Neurospora crassa and Aspergillus niger resulted in higher protein and amino acid content when compared to the uninoculated controls. Additionally, different strains under mono- and co-culture fermentations exhibited varied reduction in the ANFs. Overall, these findings suggested that pretreatment with mild water washing and/or fermentation enhances the nutritional value of HECM.

Quinoa sourdough-based biscuits with high antioxidant activity fermented with autochthonous lactic acid bacteria

To evaluate the capacity of autochthonous lactic acid bacteria (LAB) (43) from Andean grains to increase the antioxidant activity (AOA) and total phenolic compounds (TPCs) in quinoa sourdough to select best performing strains to be used as starter cultures in the elaboration of biscuits. Microbial growth (CFU per g) and pH were evaluated during quinoa dough fermentation. Counts were increased in a range of 0.61-2.97log CFU per g and pH values between 3.95 and 4.54 were determined after 24h at 30°C of fermentation. Methanolic (ME) and aqueous (AE) extracts were obtained at the end of fermentation, and free radical scavenging capacity was performed by the DPPH and ABTS methods. ME was selected for further analysis using other methods and TPC quantification. Principal component analysis showed the highest scores of growth, acidification capacity, AOA and TPC for the strains Lc. mesenteroides subsp. mesenteroides CRL 2131 and L. plantarum CRL 1964 and CRL 1973. AOA and TPC in biscuits made with sourdough from these LAB were higher than the acidified and uninoculated controls. Autochthonous LAB strains (3) increased the AOA of quinoa-based biscuits. Quinoa sourdough obtained with selected LAB is suitable as an ingredient for bakery foods with improved antioxidant status.

Development of Starter Culture for the Improvement in the Quality of Ogiri, a Food Condiment

The objective of the present study was to isolate Lactic Acid Bacteria (LAB) from ogiri, a Nigerian fermented vegetable product, with the primary focus of selecting suitable isolates as candidates for starter cultures for use in possible improvements in the quality of the product. LAB was isolated from ogiri using phenotypic methods and then subjected to technological tests to evaluate suitability as starter cultures. Based on their considerable technological properties, two isolates of LAB were selected as candidates for starter cultures. The starter cultures were inoculated at 103 CFU/g during the production of ogiri, while un-inoculated samples served as a control. The ogiri samples were stored over nine days, within which samples were taken for microbial and proximate analyses. Four LAB isolates were isolated and identified phenotypically from ogiri procured from a commercial market, including Lactobacillus acidophilus, Lactobacillus fermentum, Enterococcus sp. and Lactobacillus plantarum. The species of Lactobacillus displayed the usual cell shapes of rods when examined under the microscope, which is typical of most members of the genus. The cells of the Enterococcus sp. were, however, cocci in shape, and this is also typical of members of the genus. The basis of the identification of the LAB isolates was their ability to utilize a wide range of carbon sources in their physiological and biochemical activities. Among the LAB isolates, L. acidophilus, L. fermentum produced less than 0.35 and 0.024 mg/l of acetic acid and hydrogen peroxide respectively, and were therefore chosen as starter cultures for production of ogiri. Inoculated ogiri samples showed reduced counts of coliforms, yeast, and moulds in comparison with their un-inoculated counterparts during storage. Coliform counts increased beyond 105 CFU/g in the un-inoculated control samples, whereas counts were lower in samples inoculated with L. acidophilus and L. fermentum. Yeast and mould count of 8.1 106 CFU/g was recorded as the highest value in the un-inoculated control samples, but count was generally below 106 CFU/g in the starter culture inoculated samples. Inoculation with LAB did not have significant difference (p &gt; 0.05) in the proximate compositions of the fermented product. The LAB cultures L. acidophilus and L. fermentum demonstrated considerable control of coliforms and fungi in ogiri. Storage of the fermented product should not exceed 5 days for safety concerns, as increase in counts of coliforms was recorded beyond this period. No significant difference (p &gt; 0.05) was recorded in the proximate compositions of starter culture inoculated ogiri and un-inoculated samples. Doi: 10.28991/HIJ-2022-03-01-04 Full Text: PDF