Some environmental factors influencing the survival of Rhizobium leguminosarum bv. viceae.

Investigations were carried out to monitor the sensitivity of Rhizobium leguminosarum bv. viceae strains to various environmental stress-factors (salinity, pH, Al3+, Ca2+, Mg2+) and select them as potential candidates for Vicia faba inoculation. In the range between pH 5.0 and 10.0, the salt effect of 10-500 mM NaCl, Ca2+, Mg2+ (as chlorides and sulphates), Al2O3 and KAl (SO4)2 (25-400 microM) were tested in modified yeast-mannitol (YEM) liquid medium. Cell density of the suspensions inoculated with R. leguminosarum bv. viceae strains (initial cell-number 10(6) CFU/ml) were measured spectrophotometrically after 48 h incubation in a rotary shaker (rpm 150) at 28 degrees C. Data of optical density (OD550) are shown as percent of control (inoculated, free from treatments, pH 7.0) tubes. It was established, that results of tolerancy were in agreement with those found earlier for Rhizobium sensitivity. Strain of Lóbab Z (isolated in Hungary) however proved to have an especially outstanding survival in any media tested in vitro. Lowest observed effect concentrations (LOECs) were: 500 mM NaCl, 200 microM Al3+ (as Al2O3 or KAl (SO4)2), 50-100 mM Mg2+, and 200-300 mM Ca2+. For the Al3+, Ca2+ and Mg2+ cations, there was no variation between the stress-effect of sulphate and chloride anions. Both forms of Ca2+, however significantly reduced the growth potential of R. leguminosarum bv. viceae strains.

Metal sensitivity of some symbiotic N2-fixing bacteria and Pseudomonas strains.

An investigation was carried out to determine the sensitivity of different soil microbes (Rhizobium, Bradyrhizobium and Pseudomonas) to various metals (Cu2+, Zn2+, Co2+, Mn2+, Mo2+ and Fe2+) in vitro. Sulphate and chloride forms of these microelements were used (except Mo2+ as Na2Mo04) in 0.1, 1.0 and 10 micrograms/ml concentrations in modified YEM and nutrient broth. Growth (optical density, OD550 and OD640) of bacterium inoculated (approx. 10(6) CFU/ml) tubes, was measured spectrophotometrically after 48 h of incubation of 28 degrees C in a rotary shaker (150 rpm). Data of triplicate samples are shown as percent of control tubes (inoculated, free from treatments) and after an analysis of variance SE was calculated. Strains of Rhizobium leguminosarum proved to be the most sensitive to Cu2+, Zn2+ and Co2+. The slow growing Bradyrhizobium and plant growth promoting (PGPR) Pseudomonas isolates, however, were affected only at the highest (10 micrograms/ml) dose of these elements. In contrast Mn2+, Mo2+ and Fe2+ microelements were stimulatory for the growth of all investigated soil microbes. Sulphate forms of the most harmful Cu2+ and Zn2+ cations were more toxic than the chloride forms. An especially high diversity was found among the R. leguminosarum bv. viceae isolates. Monitoring the sensitivity of these microbes has a primary importance for selection of ecologically diverse isolates, as potential inocula in heavy-metal affected soils.

Effect of some environmental factors on Rhizobium and Bradyrhizobium strains.

Effects of different abiotic factors (acidity, salinity, nitrate and temperature) on growth rate of root-nodule bacteria (Rhizobium and Bradyrhizobium) strains were investigated in vitro. Strains isolated from Vicia faba L., Coronilla varia L. and Lupinus albus L. exhibited a large variation in tolerance of the above-mentioned factors. These bacteria should be screened under stimulated conditions for enhanced survival before selection to be used for commercial inoculant production. Linear correlation matrix data were useful to find the appropriate concentrations for the selection of the tolerant strains.

Obstetric deaths in Menoufia Governorate, Egypt.

A survey of all registered deaths which occurred during 1981-1983 in women of reproductive age was carried out in Menoufia Governorate, Egypt. Surviving family members were interviewed by trained social workers, and information was collected on symptoms of the disease that led to death. The completed questionnaires were reviewed by a panel of local physicians and a cause of death was assigned by the panel. Maternal mortality was a leading cause of death, second only to heart disease. There were 190 maternal deaths per 100,000 livebirths and 45 maternal deaths per 100,000 married women aged between 15 and 49 years. Most of the maternal deaths (63%) were due to direct obstetric causes of which haemorrhage was the main cause. Another 27% of the maternal deaths were due to indirect obstetric causes of which rheumatic heart disease was the main cause.

PIP: Trained social workers interviewed the families of 385 women of reproductive age who died during 1981-1983 in Menoufia Governorate, Egypt, to examine the women's characteristics, the causes of their deaths, and the proportion of maternal deaths due to pregnancy, delivery, and indirect obstetric factors. Maternal mortality accounted for 22.8% of all deaths to women in the reproductive age group. The dead women tended to be illiterate (76.3%), to have more than four children (51.9%), and to have died at home (53%) during the postpartum period (59%). 24% of the women died within six hours after the onset of complications. The leading cause of death in the reproductive age group was diseases of the circulatory system. The maternal mortality rate was 190/100,000 live births. There were 45 maternal deaths per 100,000 married women aged 15-49. 62.6% of the maternal deaths were attributed to direct obstetric causes, particularly hemorrhaging (51.9%). Indirect obstetric causes comprised 26.5% of the causes of death. The leading indirect obstetric cause of maternal death was diseases of the circulatory system (63.7%). In fact, rheumatic heart disease was the single leading indirect obstetric cause of maternal death, accounting for 35% of all maternal deaths. Abortion contributed to maternal mortality in 5.5% of cases. The study found various obstacles to improving maternal outcomes: late referral of patients, inadequate hospital facilities, and physicians inexperienced in the management of obstetric emergencies. Based on these findings, the researchers identified various recommendations: improve utilization of existing health facilities, increase the proportion of hospital deliveries, improve hospital care, develop a feasible system of confidential enquiries, and integrate maternal-child health centers with birth attendant teams, rural health units, family planning clinics, and local and district hospitals.