I recently started my own real estate rental business, and I'm not sure what to do with the cash

My rental generates $1,800 a month; I don't want that cash sitting in my business bank account where inflation will make this worth much less.

But how do business invest the cash into something without commingling the funds? What if I decided to buy gold with it because it generally has always held its value better long term than cash? If I ever need the cash to pay for any repairs, I just sell the gold and I understand gold isn't guaranteed to appreciate, but I'd rather take the risk than let my cash be worth less and less over the years.