Aims:  A two‐stage fermentation strategy, based on batch cultures conducted first under non‐oxygen‐limited conditions, and later under oxygen‐limited conditions, was used to improve alginate production by Azotobacter vinelandii (AT6), a strain impaired in poly‐β‐hydroxybutyrate (PHB) production. Methods and Results:  The use of sucrose as carbon source, as well as a high oxygen concentration (10%), allowed to obtain a maximum biomass concentration of 7·5 g l−1 in the first stage of cultivation. In the second stage, the cultures were limited by oxygen (oxygen close to 0%) and fed with a sucrose solution at high concentration. Under those conditions, the growth rate decreased considerably and the cells used the carbon source mainly for alginate biosynthesis, obtaining a maximum concentration of 9·5 g l−1, after 50 h of cultivation. Conclusion:  Alginate concentration obtained from the AT6 strain was two times higher than that obtained using the wild‐type strain (ATCC 9046) and was the highest reported in the literature. However, the mean molecular mass of the alginate produced in the second stage of the process by the mutant AT6 was lower (400 kDa) than the polymer molecular mass obtained from the cultures developed with the parental strain (950 kDa). Significance and Impact of the Study:  The use of a mutant of A. vinelandii impaired in the PHB production in combination with a two‐stage fermentation process could be a feasible strategy for the production of alginate at industrial level.

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Semen from Barbary sheep (Ammotragus lervia), Bighorn sheep (Ovis canadensis), Mouflon sheep (Ovis musimon), Fallow deer (Dama dama), collected by electroejaculation, and semen from Wildebeest antelope (Connochaetes taurinus), collected post mortem, were frozen using a standardized technique and a commercial freezing medium (Triladyl). Sperm quality was assessed by measuring their capacitation status (chlortetracycline assay) in addition to classic assessment: motility, viability (plasma membrane integrity), and acrosome integrity. Sperm cryosurvival measured in terms of recovery (from the initial, pre-freeze values) of motility, viability, and acrosome integrity was relatively high in most species. However, proportion of premature-capacitated spermatozoa (B+AR patterns) increased many times in relation to that of fresh semen: from 8% to 78% in Barbary sheep; from 27% to 61% in Bighorn sheep; and from 12% to 68% in Mouflon sheep. The use of a standardized technique for freezing of spermatozoa from wild ruminant species produced, in most of the cases, acceptable results. This approach may be extensively used to carry out sperm cryopreservation in field conditions. Chlortetracycline assay allowed identifying the same fluorescent patterns observed in spermatozoa from domestic animals and produced additional information on sperm cryosurvival. That is, it revealed those cells that survive freeze-thawing and are potentially fertile: noncapacitated (F pattern) and capacitated acrosome-intact spermatozoa (B pattern).