TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Inoculum: In the water purifying microbial inoculum above, the multiple-strain seed liquid is made by mixing original strains of 10-15% of Bacillus cereus, 10-15% of Bacillus subtilis, 10-15% of Pseudomonas fluorescens, 10-15% of Bacillus licheniformis, 10-15% of actinomycetes, 10-15% of Candida utilis, 10-15% of white rot, 15-30% of Lee's timber fungus, 10-15% of photosynthetic bacteria and 10-15% of Lactobacillus plantarum according to weight percentage and then inoculating the mixture into the seed culture medium. The preparation method of the multiple-strain seed liquid comprises: (a), inoculating Bacillus cereus, Bacillus subtilis, Pseudomonas fluorescens and Bacillus licheniformis into a triangular bottle from incline, shaking and culturing them for 24 hours; (b) inoculating actinomycetes, Candida utilis, white rot and Lee's timber fungus into a triangular bottle from incline, shaking and culturing them at 25 degrees C for 36-48 hours; (c) inoculating photosynthetic bacteria into a Kolle flask and culturing it at 28 degrees C for 2-3 days; (d) extracting Lactobacillus plantarum and inoculating it into the Kolle flask, culturing it at 37 degrees C for 24 hours; (e) adding and mixing the strains cultured to (d) according to the inoculating amount to obtain original microbial inoculum, then inoculating 4% of microbial inoculum into the seed pot, inoculating seed culture medium into the seed pot and culturing them to obtain multiple-strain seed liquid. The seed culture medium in the seed pot comprises 4% of original microbial inoculum, 5-8% of brown sugar, 1-2% of soybean meal, 0.2% of ammonium biphosphate, 0.15% of sodium chloride, 1% of light calcium carbonate and water as the rest, and the initial pH value is 7.0. The straw fermenting culture medium comprises 15% of wheat bran, 10% of rape seed meal, 0.5% of monoammonium phosphate, 4% of lime, 10% of coal refuse powder, 0.2% of salt and water as the rest. Additionally, the concentrated nitrifying microbial inoculum is made from 0.5 g of sodium chloride, 1 g of sodium nitrate, 0.5 g of ammonium biphosphate, 0.5 g of magnesium sulfate, 1 g of sodium bicarbonate, 1000 ml of water, and addition of nitrifying bacteria is 5% total weight of the materials above; the preparation method further comprises culturing and concentrating the mixture, ventilating and culturing the nitrifying bacteria according to the ingredients of the culture medium, culturing it at 28 degrees centigrade for 7 days, then putting it still, settling and abandoning the supernatant fluid to obtain concentrated nitrifying microbial inoculum. Using water purifying microbial inoculum made from mixed and fermented multiple-strain comprises: (a) feeding straw into an aerating system for aeration; (b) feeding the aerated straw into a chelating reaction chamber for reaction; (c) feeding the reacted straw into a fermenting chamber for fermentation; (d) inoculating 5% of multiple-strain seed liquid, 30-40% of straw fermenting culture medium and 50% of initial water in the fermenting chamber, fermenting them at 30 degrees C, supplying oxygen via ventilation control every 4-6 hours, fermenting for 72-96 hours; and (e) inoculating 2-3% of concentrated nitrified microbial inoculum into the product before discharging, stirring them uniformly to obtain the water purifying microbial inoculum. ACTIVITY - Antibacterial.