SUMMARYPhysical and nutritional factors required for growth of Bacteroides nodosus isolates from ovine foot-rot lesions were examined. Simplified anaerobic culture techniques were devised utilizing a fully soluble, autoclavable, liquid medium (TAS) which contained proteose-peptone, yeast and meat extracts and certain other essential compounds required to promote prompt and serially transferrable growth of cultures from small inocula. The latter included Trypticase, arginine, a reducing agent (most suitably thioglycollic acid) and CO,; serine and Mg2+ markedly increased growth yields. Trypticase could not be replaced by a commercial preparation of acid-hydrolysed casein; other forms of hydrolysed proteins gave delayed and inconsistent growth. Maximum growth of cultures required concentrations of 0.02 to 0.05 M-arginine, which could not be replaced by glutamic acid, citrulline or ornithine. Exogenous carbohydrate compounds were not required.The temperature range for optimum growth of cultures was 37 to 39 "C, and anaerobic culture conditions were essential for growth and the production of B. i i~d o s i i s organisms of normal morphology. Solidified TAS media for the isolation and maintenance of B. nodosus cultures were also devised.

Phenotypic and genetic parameters for clinical footscald and footrot were investigated in a pedigree flock of New Zealand Romney sheep inspected during outbreaks over six years. At inspections, each sheep's overall status with regard to footscald and footrot was summarized on a combined severity scale (Rating). Sheep were also categorized in terms of two binomial variables specifying the presence or absence of footscald or footrot (FI) and the presence or absence of footrot only (FR). A trinomial variable specified no infection, infection limited to footscald, or footrot with or without footscald (FSR), all variables being derived from the Rating value. Notwithstanding marked annual variations in prevalence of FI, F1 prevalence increased with age among ewes, and a higher prevalence of FI among male than female lambs was noted. Birth rank, birth date and dam's age had no significant effect on Rating in lambs. Repeatability of ewe Rating over successive annual inspections was low. Heritabilities of Rating, FI, FR and FSR, estimated by half-sib analyses were 0.14, 0.28, 0.17 and 0.25, respectively. Heritability of Rating estimated from dam-offspring regression was 0.12. Production traits did not appear to be genetically associated with liability to footrot. Selection of the top 5% of progenytested sires for breeding could be expected to reduce the prevalence of FI by approximately 45% per generation.

Merino sheep vaccinated with either whole Bacteroides nodosus organisms, a crude surface antigen preparation or highly purified pili (>99% homogeneity) in oil adjuvant, developed significant resistance to artificial footrot infection when compared with unvaccinated control sheep inoculated with saline-in-oil emulsion (Freund;s incomplete adjuvant) alone. The pili-vaccinated sheep generally had higher K-agglutinating antibody titres than sheep vaccinated with whole B. nodosus. These results confirmed the role of B. nodosus pilus protein both as a protective antigen and the K-agglutinogen. Vaccines prepared with Freund;s incomplete adjuvant containing either purified pili, crude pili or B. nodosus whole cells did not produce significantly different injection-site reactions.

One hundred and fifty-five strains of marine bacteria have been isolated from oceanic waters in the New Zealand region, at depths from 50 to 2000 m. A further 36 luminous strains were isolated from light organs and intestines of fish. All isolates were characterised using a series of morphological, physiological, and biochemical tests, and the results of these tests were subjected to numerical analysis using a digital computer to group the strains according to the similarity of their features. This sorting procedure differentiated seven principal groups among the isolates. The genera Moraxella, Vibrio and Pseudomonas were all represented in the groups. Most strains of the luminous bacteria have been accommodated in the species Vibrio fischeri and Photobacterium phosphoreum. P. phosphoreum strains were common in deepwater samples but were also isolated from fish light organs. V. fischeri strains originated from fish-gut contents. The main features and relationships of the group are tabulated, together with quantitative data on the abundance of bacteria with depth and latitude. No obligate psychrophilic bacteria were isolated from water samples processed at low temperatures.

MATERIALS AND METHODS Cultural methods. Liquid and solidified Trypticase (BBL Microbiology Systems, Cockeysville, Md.) arginine-serine (TAS) media (25) were used for maintaining strains and as basal media for biochemical tests. TAS isolation medium was also used as originally