@Neil Thirumuttam
I have been interested in probiotic cultures used as health drinks for several years now, and in fact, have distributed probiotic cultures to hobbyist on Aquapetz meetings! Rajiv, Mankotia, and Arjun have all taken them from me. Vishaal Dalal was initially interested, but I am not sure he still is. He helped me find the Kombucha SCOBY again, the last one I personally had died years ago.
I am currently using probiotic culture of Kombucha to transfer beneficial bacteria through vinegar eels to fry. It is one of three types of probiotic culture I maintain.
I do not believe they can be used to kill algae, since bacteria do not inhabit the same niche as algae, so they cannot take the place where algae grow and crowd the algae out. but they can surely grow in places where disease causing pathogenic bacteria grow, and thereby prevent disease.
The field of probiotics for fish aquairums is very fascinating but still in its infancy. This is because it requires an understanding of beneficial bacteria/fungi and other microorganisms in human beings first, before you can understand their usefulness in an aquarium for fish.
Probiotics is one of the many reasons I favour live food over dry food (but I have always used both, never being without Tetrabits or Hikari). It is also the reason I HATE introducing chemicals to aquariums that kill microorganisms blindly. The famous Natural Aquarium expert and scientist Diana Walstad proved that fishes carry germs of most diseases like ich all the time. it is only when the natural equilibrium among naturally occurring microorganisms is disturbed in an aquariums that the germs increase in numbers and cause the disease. One example is Fish tuberculosis (TB).
Of the two articles you have so helpfully shared, I do not approve of the second article that tries to sell a 'sludge' that kills bad bacteria. I do not think it is possible to be so specific as to know exactly what type of bacteria you are introducing that they will counter the exact type of bacteria/algae/cyanobacteria (which are both bacteria and algae) that you want to kill. No. What is possible is to avoid strong chemicals and absurd technological applications like UV lamps for water in small aquariums, and to use food to introduce healthful beneficial bacteria and other organisms in fish food so that they colonise the gut of the fish. These cover the digestive tract so well that there is no space left for pathogenic bacteria to stick and cause disease in their bodies. at the very least, it is more difficult for disease germs to get space where healthful bacteria already live and multiply.
Probiotics is a very wide term, it can cover not only the bacteria in probiotic foods that we might indirectly feed fish with, but also the bacteria that live in a filter and appear naturally in healthy thanks. in that sense, every cycled aquarium has them in small or large numbers. They are already sold in sealed bottles by many companies (including Sera) but their efficacy is debatable, since we need a lot of research to find out for sure if they remain alive after so long in a closed environment. I feel the term should be only used for bacteria in food that we can feed fish, for others to understand better.
My cocopeat tubifex culture is till not ready, it keeps disappointing me.
if you like, I can send you a probioitic kombucha culture that I am using successfully for vinegar eels. Vijendra Suryavanshi is also using it in Delhi now. And Monty Chadda will be also given a piece soon
My post is already very long, but I haven't covered growing plants vis-à-vis probiotic application. I am sure you have already heard of vermicompost. the compost is very good for plant growth if it is first aged properly. the special worms (many species, most common is eisenia fetida) can be kept at home which convert any organic waste to compost that can be used in the substrate for growing plants, in about 2 months. This compost is full of healthy bacteria that prevent disease in plants or anywhere it is used. the worm species is easily available from any plant nursery that sells raw vermicompost (not in bags) since there are always worms in it. it is also sold in Govt. agencies to farmers. Plants can also be sprayed with 'vermicompost tea' (just google it!) which creates a layer of good bacteria on plants that is believed to prevent harmful pests from attacking leaves. It also prevents nutrient deficiencies.