Study On The Bacteriostatic Mode Of Halostachys Caspica Extract Against S.aureus And Its Effect Of Rumen Cellulolytic Bacteria Strains

Halostachys caspica is a kind of forage resource with high nutritional value,but its extract has strong bacteriostasis,and it will cause rumen disease when sheep eat too much.In order to give full play to the application value of Halostachys caspica in animal husbandry,the effect of Halostachys caspica on rumen microorganism was explored.In this experiment,the effects of n-butanol extract from Halostachys caspica on cell membrane and cell wall of Staphylococcus aureus(S.aureus)and on rumen cellulolytic bacteria strains were studied,which laid a foundation for the rational application of Halostachys caspica feed.The main research contents and results of this experiment are as follows:The inhibitory effect of n-butanol extract from Halostachys caspica were determined by multiple dilution method,and the changes of electrolyte and extracellular protein content in the culture medium were measured to study the effect of n-butanol extract on the membrane permeability of Staphylococcus aureus,then the effect of n-butanol extract on cell wall was studied by the changes of alkaline phosphatase(AKP)content and observation on the microstructure of cell.The results showed that the MIC and MBC of n-butanol extract from Halostachys caspica to Staphylococcus aureus were 25 mg/mL and 50 mg/mL respectively,the conductivity,protein and AKP content of the culture solution increased significantly after adding n-butanol extract into the culture solution.At the same time,it was observed by scanning electron microscope that n-butanol extract of Halostachys caspica could deform the cell morphology and leak out the cell content.The results showed that the bacteriostatic effect of n-butanol extract was through destroying the integrity of cell membrane and cell wall of Staphylococcus aureus.Rumen cellulolytic bacteria strains were isolated and purified by colony morphology observation and Gram staining,then the ability of cellulolytic bacterium was detected by Congo red medium.Finally,the species of rumen cellulolytic bacteria strains were identified by the physiological and biochemical characteristics analysis and 16 Sr DNA sequence analysis.Five cellulolytic bacteria strains from rumen fluid were isolated.After comparison with GenBank database in NCBI,they can be preliminarily identifiedas Bacillus subtilis strain,Bacillus halotolerans strain,Bacillus velezensis strain,Bacillus tequilensis strain and Bacillus licheniformis strain respectively.The antibacterial activity of Halostachys caspica extract against five rumen cellulolytic bacteria strains were tested in vitro.The results showed that the n-butanol extract had obvious inhibitory effect on five rumen cellulolytic bacteria strains,and the MIC was 25 mg/mL.The results showed that the activity of rumen cellulolytic bacteria strains was inhibited by eating too much Halostachys caspica,which was easy to cause digestive system diseases such as retention of food in rumen.Based on the above results,in order to give full play to the nutritional and medicinal value of Halostachys caspica,it should be avoided to be used as a single feed.According to the nutritional composition of Halostachys caspica and the nutritional level required by Karakul Sheep,Halostachys caspica diet can be prepared.