Florida International University Microbes Questions

please answer those 2 questions.

1-According to the videos above, I would consider microbes to be the foundation of life, as without them life would perish. If life were to perish due to the absence of the world’s microbiome, is there a way to restore it? Would it restore itself naturally as it once happened when microbes first appeared on Earth 3.8 to 4.3 billion years ago? Would it be ethical or even possible to produce “man-made” microbiomes and carefully select only those microbes that are needed and NOT the ones that cause disease?

2) If we lived in a world without microbes, do you think there could be a replacement for microbes using technological advances? If so, what processes would you choose to help sustain the earth? Likewise, how would we implement them?