Characterisation and biochemical properties of predominant lactic acid bacteria from fermenting cassava for selection as starter cultures.

A total of 375 lactic acid bacteria were isolated from fermenting cassava in South Africa, Benin, Kenya and Germany, and were characterised by phenotypic and genotypic tests. These could be divided into five main groups comprising strains of facultatively heterofermentative rods, obligately heterofermentative rods, heterofermentative cocci, homofermentative cocci and obligately homofermentative rods, in decreasing order of predominance. Most of the facultatively heterofermentative rods were identified by phenotypic tests as presumptive Lactobacillus plantarum-group strains, which also comprised the most predominant bacteria (54.4% of strains) isolated in the study. The next predominant group of lactic acid bacteria (14.1% of total isolates) consisted of obligately heterofermentative rods belonging either to the genus Lactobacillus or Weissella, followed by the heterofermentative cocci (13.9% of isolates) belonging to the genera Weissella or Leuconostoc. Homofermentative cocci were also isolated (13.3% of isolates). Biochemical properties such as production of alpha-amylase, beta-glucosidase, tannase, antimicrobials (presumptive bacteriocin and H(2)O(2)-production), acidification and fermentation of the indigestible sugars raffinose and stachyose, were evaluated in vitro for selection of potential starter strains. A total of 32 strains with one or more desirable biochemical properties were pre-selected and identified using rep-PCR fingerprinting in combination with 16S rRNA sequencing of representative rep-PCR cluster isolates. Of these strains, 18 were identified as L. plantarum, four as Lactobacillus pentosus, two each as Leuconostoc fallax, Weissella paramesenteroides and Lactobacillus fermentum, one each as Leuconostoc mesenteroides subsp. mesenteroides and Weissella cibaria, while two remained unidentified but could be assigned to the L. plantarum-group. These strains were further investigated for clonal relationships, using RAPD-PCR with three primers, and of the 32 a total of 16 strains were finally selected for the development as starter cultures for Gari production.

Comparative sequence analysis of the South African vaccine strain and two virulent field isolates of Lumpy skin disease virus.

The genomic sequences of 3 strains of Lumpy skin disease virus (LSDV) (Neethling type) were compared to determine molecular differences, viz. the South African vaccine strain (LW), a virulent field-strain from a recent outbreak in South Africa (LD), and the virulent Kenyan 2490 strain (LK). A comparison between the virulent field isolates indicates that in 29 of the 156 putative genes, only 38 encoded amino acid differences were found, mostly in the variable terminal regions. When the attenuated vaccine strain (LW) was compared with field isolate LD, a total of 438 amino acid substitutions were observed. These were also mainly in the terminal regions, but with notably more frameshifts leading to truncated ORFs as well as deletions and insertions. These modified ORFs encode proteins involved in the regulation of host immune responses, gene expression, DNA repair, host-range specificity and proteins with unassigned functions. We suggest that these differences could lead to restricted immuno-evasive mechanisms and virulence factors present in attenuated LSDV strains. Further studies to determine the functions of the relevant encoded gene products will hopefully confirm this assumption. The molecular design of an improved LSDV vaccine is likely to be based on the strategic manipulation of such genes.

Dental education in relation to the needs of the South African community.

The dental needs of a heterogeneous South African community are not being fully met because the majority of the already deficient dentist population is in private practice, mostly in urban areas, where they are rendering services to a small minority of the population who can afford comprehensive dental care. Contrary to public health services in general, public dental services are inadequate in extent and provide a limited range of treatment to some eighty-five per cent of the population. Millions of under-privileged people, particularly in rural areas, are not within range of any professional dental care whatsoever. Organized community preventive programmes and dental health education on a national basis are non-existent. Water fluoridation has not yet become a reality. Realizing the shortcomings in community dental services the Government recently adopted a national dental health policy which is aimed at limiting and preventing dental diseases and also at expanding the public dental service to bring it within reach of all sections of the community. In order to meet the dental needs of the community and also to give momentum to the national dental health policy, the following steps are being taken as far as dental education is concerned: (i) The Department of Health is planning to assist universities to establish departments of community dentistry with the object of promoting extended education in community dentistry at under-graduate and post-graduate level. (ii) Consideration is being given to a scheme whereby dental students will have to do one year compulsory intership. (iii) Additional dental schools are being established to enable more non-White dentists to qualify. (iv) With the extended education in community dentistry it is hoped to draw more dentists into community dental services. (v) Dental therapists are being educated to perform duties such as extractions, simple fillings, prevention and dental health education, under the supervision of dentists, in areas where the shortage of dentists is most crucial.