Analysis of fatty acid composition of anaerobic rumen fungi.

The fatty acid (FA) composition of fresh mycelia of anaerobic rumen fungi was determined. The fatty acids methyl esters (FAME) of six strains belonging to four genera (Neocallimastix, Caecomyces, Orpinomyces, Anaeromyces) and one unknown strain were analyzed by gas chromatography. All studied fungi possess the same FAs but differences were found in their relative concentrations. The FA profile of anaerobic fungi comprises carbon chains of length ranging from 12 to 24; the most common fatty acids were stearic (C(18:0)), arachidic (C(20:0)), heneicosanoic (C(21:0)), behenic (C(22:0)), tricosanoic (C(23:0)) and lignoceric (C(24:0)) with relative amount representing >4% of total FA. Significant differences were determined for heptadecanoic, oleic, behenic and tricosanoic acids. Rumen anaerobic fungi can contain very long chain fatty acids; we found unsaturated fatty acids including cis-11-eicosenoic (C(20:1)), cis-11,14-eicosadienoic (C(20:2)), erucic (C(22:1n9)), cis-13,16-docosadienoic (C(22:2)) and nervonic (C(24:1)) acids in very small amounts but their presence seems to be unique for anaerobic fungi.

Diversity of insect intestinal microflora.

The influence of geographic location, season, age, and part of the digestive tract on bacterial diversity was evaluated on intestinal microflora of honeybees, wasps, and cockroaches using DGGE analysis. PCR-DGGE analyses with universal bacterial primers targeting 200-bp region of the 16S rDNA gene afforded the profile of complex bacterial DNA; specific primers were used to determine the profile of bifidobacteria whose concentration in digestive tract was determined by real-time PCR. Selected PCR products were identified by sequencing. The microflora of the bees exhibited little variations among the hives from distant locations. Their bifidobacterial population formed 2.8-8.4 % of total bacteria and was very homogeneous. The total gut microflora of wasps was also homogeneous, only two samples being affected by the season or the location; on the other hand, wasp bifidobacterial population was very heterogeneous. Cockroaches showed the highest variations in microflora composition, the age and diet being the ultimate factors; bifidobacteria counts also varied among tested individuals (0.1-34.1 % of total bacteria). Our results suggest that nutrition habits are the strongest factor affecting the insect microflora, giving higher variations to omnivorous species.