Study On Fermentation Conditions Of Antibiotics Produced By Paenibacillus PLD-01

In this paper,the isolation and identification of antibiotic PLD-01,the conditions of liquid fermentation,the acute and subacute toxicity test of mice and the application in fruit juice beverage were studied.The research content mainly includes four aspects:1.Isolation and identification of antibiotic PLD-01In this paper,several strains with strong antibacterial activity were isolated from the giant panda feces,and one strain,PLD-01,which had the largest diameter of the inhibition zone,was selected.The strain was a bacterium with wide antibacterial spectrum.The 16 S rDNA sequence was extracted and its 16 S rDNA sequence was compared with that of Paenibacillus cookii.The phylogenetic tree of Phylip Inter-face was used to construct the phylogenetic tree.The results showed that there was a high homology with Paenibacillus cookii,indicating that the strain PLD-01 was closest to paenibacillus.PLD-01 was identified as paenibacillus sp.2.Study on liquid fermentation conditions of antibiotic PLD-01The fermentation conditions of antibiotic PLD-01 were studied by single factor,orthogonal and response surface tests.The effects of the factors of the culture medium and the factors of the fermentation conditions on the antibacterial properties of the antibiotic PLD-01 were studied by using Minitab 15 software to analyze and plot the response surface data.The results showed that the best medium of PLD-01 was 1% glucose,2% soybean meal and KH2PO4 as inorganic salt.The optimum culture conditions for PLD-01 were temperature 36 ?,fermentation broth pH 7,shaking speed 179 r · min-1.3.Acute and subacute toxicity test of antibiotic PLD-01 against miceThis chapter examines the acute toxicity and subacute toxicity of antibiotics PLD-01 against mice.The results showed that after treatment with different doses of antibiotics PLD-01,the mice were not affected by eating,drinking,exercise and other activities,that is,no obvious poisoning phenomenon,no death,animal fur,visual observation of the main dirty Heart,liver,spleen,lung,kidney and so no abnormal changes.Indicating that PLD-01 on mice acute oral toxicity is "non-toxic" level.In the subacute toxicity test,there was no significant difference in weight gain,organ coefficient,blood index and physiological and biochemical indexes between the experimental group and the control group,indicating that paenibacillus sp.was safe in the dose range.4.Application of antibiotic PLD-01 in fruit juice beverageThe bacteriostatic effect of antibiotic PLD-01 was evaluated by measuring the diameter of inhibition zone,and the antibacterial map of several common animal pathogens was listed.The results showed that paenibacillus sp.had a broad-spectrum bacteriostatic effect on pathogens(Staphylococcus aureus,Escherichia coli and Proteus vulgaris),and had no significant inhibitory effect on probiotics(Lactobacillus acidophilus,Bifidobacterium lactis,Bifidobacterium longum)effect.Antibiotic PLD-01 was applied to fruit juice beverage,and its antibacterial effect was tested in the beverage.The results showed that the freshness of the antibiotic PLD-01 treatment group was significantly higher than that of the blank control group,which indicated that the freshness of PLD-01 fermentation broth was good.When the antibiotic PLD-01 is added at 1% and 5%,the orange juice and grape juice can be stored on day 7 at room temperature and in cold conditions.At room temperature,the 1% addition was the highest in the sensory evaluation,so the optimal dosage of 1% was the amount of antibiotic PLD-01.