Python程序在终端运行时工作，但在PHP脚本运行时无法访问lib

I have a python program that works fine. When I run it through terminal I get the wanted output. But now I'm trying to execute it through a PHP script, and I keep receiving a import error message.

After some research, I edited my python code, adding the line

print (sys.path)

The output was different when run by terminal and by PHP script. Then I added the line

sys.path.insert(0,path)

to add the missing path during the PHP execution, but it didn't solve the problem (even though I can see the path in the list when I print the sys.path).

I also tried variations like os.environ['PATH'] += ':'+path. But it didn't work either.

This is my PHP code that is not working:

<?php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);
exec('/usr/bin/python3 /var/teste.py 2>&1', $out);
print_r($out);
?>

But when I type:

python3 /var/teste.py

on terminal, it works. When I'm executing the PHP script I have the following message:

import mysql.connector [3] => ModuleNotFoundError: No module named 'mysql'.