Nodulation Compatibility and Symbiotic Performance of Rhizobia spp. With Different Landraces of Bambara Groundnut (Vigna Subterranea (L.) Verdc.) Collections

The symbiosis of the legume bambara groundnut (Vigna subterranean L.Verde) with its rhizobial partners has not been studied sufficiently compared to several other legumes throughout Africa. In this study, a nodulation compatibility screening was conducted on 16 different landraces of this legume using five Rhizobia strains previously isolated from active nodules of Desmodium uncinatum, Arachis hypogaea, Cyamopsis tetragonoloba, Glycine max and Phaseolus vulgaris and deposited at the South African Rhizobium Culture Collection (SARCC). A screening assay was conducted under glasshouse to select compatible rhizobia strains that nodulate and enhance growth in one or more genotypes of V. subterranean (L.) Verdc. Pre-germinated seeds of each landraces planted in sterile river sand medium were inoculated with 108 cfu ml-1 of the rhizobial strains (2ml/seed) and monitored with regular watering for six weeks. Parameters such as nodule number, nodule color and positions, plant biomass were determined in test genotypes. Significant differences were observed among landraces in nodule number and plant biomass, and among rhizobial strains in nodule number. Principal component analysis (PCA) showed that root nodule rhizobia strains SARCC-388 and SARCC-578 characterized as Bradyrhizobium zhangiangens and Bradyrhizobium centrosematis, respectively exhibited the highest nodulation compatibility with one or more bambara groundnut landraces. This study demonstrated that many of the bambara landraces did not show nodulation preference to a unique group of rhizobia, confirming that V. subterranean (L) Verdc can be nodulated by more than one species of rhizobia, especially by rhizobia belonging to the cowpea miscellany cross inoculation group.

Fortified Fermented Rice-Acid Can Regulate the Gut Microbiota in Mice and Improve the Antioxidant Capacity

The study aimed to explore the effects of fortified fermented rice-acid on the antioxidant capacity of mouse serum and the gut microbiota. Hair characteristics, body mass index, intestinal villus height, intestinal crypt depth, serum antioxidant capacity, and gut microbiota of mice were first measured and the correlation between the antioxidant capacity of mouse serum and the gut microbiota was then explored. The mice in the lactic acid bacteria group (L-group), the mixed bacteria group (LY-group), and the rice soup group (R-group) kept their weight well and had better digestion. The mice in the L-group had the better hair quality (dense), but the hair quality in the R-group and the yeast group (Y-group) was relatively poor (sparse). In addition, the inoculation of Lactobacillus paracasei H4-11 (L. paracasei H4-11) and Kluyveromyces marxianus L1-1 (K. marxianus L1-1) increased the villus height/crypt depth of the mice (3.043 ± 0.406) compared to the non-inoculation group (R-group) (2.258 ± 0.248). The inoculation of L. paracasei H4-11 and K. marxianus L1-1 in fermented rice-acid enhanced the blood antioxidant capacity of mouse serum (glutathione 29.503 ± 6.604 umol/L, malonaldehyde 0.687 ± 0.125 mmol/L, catalase 15.644 ± 4.618 U/mL, superoxide dismutase 2.292 ± 0.201 U/mL). In the gut microbiota of L-group and LY-group, beneficial microorganisms (Lactobacillus and Blautia) increased, but harmful microorganisms (Candidatus Arthromitus and Erysipelotrichales) decreased. L. paracasei H4-11 and K. marxianus L1-1 might have a certain synergistic effect on the improvement in antibacterial function since they reduced harmful microorganisms in the gut microbiota of mice. The study provides the basis for the development of fortified fermented rice-acid products for regulating the gut microbiota and improving the antioxidant capacity.

Pneumococcal Colonisation is an Asymptomatic Event in Healthy Adults using an Experimental Human Colonisation Model

IntroductionPneumococcal colonisation is regarded as a pre-requisite for developing pneumococcal disease. In children previous studies have reported colonisation to be a symptomatic event and described a relationship between symptom severity/frequency and colonisation density. The evidence for this in adults is lacking in the literature. This study uses an experimental human pneumococcal challenge model to explore whether pneumococcal colonisation (or co-colonisation with a respiratory virus) is a symptomatic event in healthy adults.MethodsHealthy volunteers aged 18-50 were recruited and inoculated intra-nasally with either Streptococcus pneumoniae (serotypes 6B, 23F) or saline as a control. Respiratory viral swabs were obtained prior to inoculation. Nasal and non-nasal symptoms were then assessed using a modified Likert score between 1 (no symptoms) to 7 (cannot function). The rate of symptoms reported between groups was compared and a correlation analysis performed.ResultsData from 54 participants were analysed. 46 were inoculated with S. pneumoniae (29 with 6B, 17 with 23F) and 8 received saline. In total, 14 became experimentally colonised (30.4%), all of which were inoculated with 6B serotype. There was no statistically significant difference in nasal (p= 0.45) or non-nasal symptoms (p=0.28) between the pneumococcal inoculation group and the saline group. There was no direct correlation between colonisation density and symptom severity in those who were colonised. In the 22% (12/52) who were co-colonised with pneumococcus and respiratory viruses there was no statistical difference in either nasal or non-nasal symptoms (virus positive p=0.74 and virus negative p=1.0).ConclusionPneumococcal colonisation is asymptomatic in healthy adults, regardless of bacterial density or viral co-colonisation.

The Diversity of Legume-Nodulating Bacteria from Several Agroecosystems in Sumberjaya, Lampung

Bacteria that capable of forming root nodules on legumes are known as Rhizobia. They have also known as Legume- Nodulating Bacteria (LNB). They can fi x nitrogen from the atmosphere. Diversity of Legume-Nodulating Bacteria is affected by biotic factors (such as their genetic factors, plants, and competition with the other soil microbes) and abiotic factors (such as land use, soil’s temperature, pH, chemistry and soil’s properties). The aim of this experiment is to know the diversity of eleven Legume- Nodulating Bacteria based on their phenotypic and genotypic characters. The eleven LNB used in this experiments were isolated from several agroecosystems in Sumberjaya, Lampung. The analysis of these LNB diversity were carried out by characterizing both phenotypic and genotypic properties. The diversity analysis showed that the eleven LNB isolates had high diversity, based on nodule formation, and classifi ed into two groups of cross inoculation group. Key words: Rhizobia, phenotypic diversity, genotypic diversity

Influence of AMF on Oat Used to Phytoremediation in Petroleum Contaminated Soil

Petroleum, one of the main energy resources, plays an important role in the progress of human culture. With the development of petroleum industry, soil contamination by petroleum products has become a worldwide environment problem. This study investigated the effects of inoculation using microorganism, identified as an arbuscular mycorrhizal fungus (AMF), Glomus intraradices on oat under petroleum stress using a pot experiment in greenhouse. The concentration of petroleum in the tested soils was 5000mg/kg. The results showed that the degradation rate of the total petroleum hydrocarbons (TPHs) of the inoculation treatments was significantly higher than the non-inoculation group. By detection the index of plant growth and physiology, such as soluble protein and MDA, the results showed that all the inoculation treatments increased plant tolerance to the TPHs stress and which could promote the phytoremediation.

EFFICACY OF CYTOTOXIC AGENTS FOR PREVENTION OF TUMOR GROWTH AFTER TUMOR CONTAMINATION AND BLOCKS INOCULATION: AN IN VIVO COMPARATIVE STUDY OF CISPLATIN AND DISTILLED WATER, POVIDONE IODINE, HYDROGEN PEROXIDE AND SALINE IN ATHYMIC MICE

We tested the efficacy of 4 local agents for protection against tumor growth after tumor contamination and tumor bloc inoculation. Tumors were prepared by injecting human HT-1080 fibrosarcoma cells into the subcutaneous tissue of 6–9 week old male athymic nude mice (BALB/c nu/nu). When the tumors reached the desired size, the nude mice were sacrificed, and the tumors were harvested en bloc. Then the tumors were used in either contamination group or tumor inoculation group. In the contamination group, 34 tumors were cut by Gigli saw (Group G) and 35 tumors were cut by No. 11 scalpel (Group S). The cut surface of the tumor was rubbed into the subcutaneous tissues of non-tumor bearing nude mice for 10 seconds. Then, the nude mice from the S and G groups were randomized into either one of five subgroups: groups S–N and G–N: no local agent was used, groups S–S and G–S: lavage by saline, groups S–P and G–P: lavage by povidone iodine 10%, groups S–H and G–H: lavage by hydrogen peroxide 3%, groups S–C and G–C: lavage by cisplatin and distilled water. In the tumor inoculation group, a tumor weight of 100 mg was inoculated into 32 non-tumor bearing nude mice. Then, the nude mice were randomized into either of 5 subgroups: group B–N: no local agent was used, group B–S: lavage by saline, group B–P: lavage by povidone iodine 10%, group B–H: lavage by hydrogen peroxide, group B–C: lavage by cisplatin and distilled water. For lavage, the fluid was kept in the wound for 5 minutes apart from the cisplatin which was kept in the wound for 2.5 minutes and then the wound was filled with distilled water for the next 2.5 minutes. Tumor growth occurred in S–N, S–S, S–H, S–P and S–C groups in 33.3%, 67.7%, 16.7%, 16.7%, and 0% respectively. Tumor growth occurred in G–N, G–S, G–H, G–P, and G–C groups in 50%, 67.7%, 33.3%, 33.3%, and 0%, respectively. The total growth incidence after tumor contamination in the no-agent, saline, hydrogen peroxide, povidone iodine and cisplatin groups were 41.7%, 58.3%, 25%, 25% and 0%, respectively. Growth occurred in 100% of B–N and B–S groups, 83% of B–H and B–P groups and 33.3% of the B–C group. Cisplatin used for 2.5 minutes followed by distilled water for 2.5 minutes is effective for protection against local tumor recurrence due to tumor contamination. It also has a reasonable effect against tumor blocks.

Genetic diversity ofSinorhizobiumpopulations recovered from differentMedicagovarieties cultivated in Tunisian soils

A collection of 468 rhizobial isolates was obtained from different ecological areas of Tunisia by trapping them on Medicago sativa cv. Gabes, Medicago scutelleta cv. Kelson, Medicago truncatula, and Medicago ciliaris. A subsample of 134 rhizobia was chosen to determine their plasmid profile, and 89 isolates were subjected to multilocus enzyme electrophoresis (MLEE) and PCR/RFLP analysis using 16S, IGS (inter genic spacer), and nifKD probes. Twenty-five representatives from these isolates were evaluated for their nodulation and nitrogen fixation capacities. MLEE studies revealed two groups with highly heterogeneous host specificity and geographical origin. The discriminatory power was found to be slightly better with the amplified ribosomal intergenic region, than the nifKD genes. Divisions detected by nifKD amplified DNA analysis matched those established by ribosomal PCR- RFLPs. The comparison between different analyses revealed that MLEE illustrated better phenotypic properties of isolates than PCR-RFLP or plasmid content analysis. Clear distinction between Sinorhizobium meliloti and Sinorhizobium medicae were observed by analysis of the IGS symbiotic regions between nifD and nifK genes. Were able to distinguish three inoculation groups; isolates trapped from M. sativa cv. Gabes and M. scutelleta cv. Kelson formed one inoculation group which was more closely related to isolates trapped from M. truncatula than those trapped from M. ciliaris.Key words: Sinorhizobium, Medicago, diversity, MLEE, PCR, symbiotic effectiveness.