The lowest estimated number is 3 million, with the highest reaching 1 billion.

Currently, a widely accepted number was proposed by Professor Camilo Mora from the University of Hawaii at Manoa:

8.7 million, excluding viruses.

This number was estimated using the application of biological classification hierarchies—essentially the trends in the number of kingdoms, phyla, classes, orders, families, genera, and species as learned in biology textbooks (org/content/113/21/5970).

For example, a phylum of animals = 10 classes = 100 orders = 1000 families = 10000 genera = 100000 species, with similar trends in the number of classification ranks among different groups, and higher classification levels being more stable compared to species.

Therefore, after a series of simulations, a more reliable total species number can be estimated.

Professor Camilo Mora's paper is currently one of the most cited statistical manuscripts worldwide and can be considered a relatively authoritative hypothesis.

8.7 million compared to 2 million.

Therefore, discovering the existence of one or even multiple microorganisms within moss did not surprise Xu Yun at all.

After a moment of contemplation, he said to Qiu Sheng:

"Old Qiu, let's start with the 16S similarity test first."

Qiu Sheng nodded, quickly put on gloves, and said:

"Alright, I'll do it immediately."

Generally speaking,

if the strain was cultivated in a petri dish, the difficulty of the test or comparison is often not high.

But if the target is a sample enriched from nature, the operation becomes more troublesome.

The 16S similarity test mentioned by Xu Yun refers to the detection of the RNA component of the ribosomal small subunit,

which is 16S rRNA.

This part has a length of about 1500 nt, slightly varying between different species. It is considered one of the mainstream procedures for detecting new organisms.

Five minutes later.

Qiu Sheng looked up and said to Xu Yun:

"Old Xu, it's ready. Which primer do you think we should use?"

Xu Yun thought for a moment and quickly said:

"1492R, I suppose."

"Got it!"

Half an hour later.

Qiu Sheng looked up and snapped his fingers:

"Done, it's amplified. You have the BLAST key, right?"

Xu Yun gave him a thumbs up to indicate a job well done, then walked over to the workstation and rapidly inputted a long string of keys.

Those who have done tests for new species should know.

The threshold for 16S similarity testing is somewhat vague because the threshold for similarity testing varies among different taxonomic groups.

For example, some have a threshold of 97%, others 99%.

Usually,

if the similarity is over 97%, it is considered the same species.

If the similarity is below 97%, it is considered a different species, and the next stage of testing is conducted.

However, this relatively imprecise testing method is still an obstacle for detecting many new organisms:

The majority of samples, after testing, will show a similarity of 99.99% with some other microorganism, indicating they are the same species.

In any case.

This technology is reliable for genus classification.

After a while.

Qiu Sheng looked up with a face full of surprise, his voice suddenly heightened:

"Old Xu, the similarity is 46.9%, 46.9%!!"

"Undoubtedly, this is a novel organism!"

Xu Yun seriously looked at him and confirmed:

"Only one new organism?"

"That's right, only one!"

Xu Yun nodded thoughtfully and then said:

"Then continue with the phospholipid fatty acid and respiratory quinone identification."

As is known.

New organism identification generally involves nine steps:

1. 16S similarity.

2. Morphological observation.

For instance, looking at the shape, size, and flagella of the bacteria, etc. It also includes determining the optimal growth conditions.

3. Phospholipid fatty acid identification, which has genus specificity.

4. Respiratory quinone, checking which predominant respiratory quinone it has, with species specificity.

5. Molecular hybridization, that is, determining the genomic sequence, a draft is sufficient, and then comparing it with closely related species.

Similarities over 70% are considered the same species, below 70% as different species.

6. Utilization of carbon sources, checking which carbon sources can be utilized, with a total of 95 carbon source tests.

7. API kit identification, an aspect of physiological and biochemical identification.

8. GC content.

9. Gram staining.

After these examinations, it can be determined whether it is a new species. (Note: I'm not sure if providing such detailed writing makes everyone willing to read it or not? This kind of detailed procedure is probably not covered in other writings, and asking around is actually troublesome. If it still seems verbose, I won't write it in such detail next time)

The fifth step, molecular hybridization, can be directly ignored this time—as the 46.9% difference detected in the first step is really too obvious.

Considering the time issue, Xu Yun distributed the steps one by one, assigning them to several team members to perform synchronously.

Five hours later.

A final report was produced.

"A completely new microorganism of the genus Alternaria, observable under a 1000x oil immersion microscope, featuring abundant pseudohyphae externally."

"This pseudohyphae can be isolated, binding with the target to complete some chemical reaction, is this... a bald attack?"

"Within a piece of moss, a high-density enrichment of 8000 units of the novel organism was found, having certain similarities with Lactobacillus acidophilus in characteristics... hmm?"

Afterward, looking at one section of the report, Xu Yun raised his head in puzzlement and asked Qiu Sheng:

"Old Qiu, is the new organism's effect on purifying food residues the most significant?"

Qiu Sheng nodded and pointed to a petri dish not far away:

"Our preliminary testing indicates that this novel microorganism can effectively inhibit the generation of ammonia, organic acids, and sulfides in residues."

"Moreover, it has a strong lethal effect on bacteria like Neisseria and Anaerobic Streptococcus."

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